SAS controllers from Adaptec. Fast and agile. Hard drive connection interfaces: SCSI, SAS, Firewire, IDE, SATA sas connectors
In modern computer systems SATA and SAS interfaces are used to connect the main hard drives. As a rule, the first option suits home workstations, the second – server ones, so the technologies do not compete with each other, meeting different requirements. The significant difference in cost and memory capacity makes users wonder how SAS differs from SATA and look for compromise options. Let's see if this is advisable.
SAS(Serial Attached SCSI) is a serial interface for connecting storage devices, developed on the basis of parallel SCSI to execute the same set of commands. Used primarily in server systems.
SATA(Serial ATA) – serial data exchange interface based on parallel PATA (IDE). Used in home, office, multimedia PCs and laptops.
If we talk about HDD, then, despite the different specifications and connectors, there are no fundamental differences between the devices. Backward one-way compatibility makes it possible to connect drives to the server board using both one and a second interface.
It is worth noting that both connection options are also possible for SSDs, but the significant difference between SAS and SATA in this case will be in the cost of the drive: the first can be tens of times more expensive for a comparable volume. Therefore, today such a solution, if not rare, is quite well-considered, and is intended for fast enterprise-level data processing centers.
Comparison
As we already know, SAS is used in servers, SATA in home systems. In practice, this means that the former are accessed by many users at the same time and many tasks are solved, while the latter are dealt with by one person. Accordingly, the server load is much higher, so the disks must be sufficiently fault-tolerant and fast. SCSI protocols (SSP, SMP, STP) implemented in SAS allow more I/O operations to be processed simultaneously.
Directly for HDD, the circulation speed is determined primarily by the spindle rotation speed. For desktop systems and laptops, 5400 – 7200 RPM is necessary and sufficient. Accordingly, it is almost impossible to find a SATA drive with 10,000 RPM (unless you look at the WD VelociRaptor series, intended, again, for workstations), and anything higher is absolutely unattainable. SAS HDD spins up at least 7200 RPM, 10000 RPM can be considered the standard, and 15000 RPM is a sufficient maximum.
Serial SCSI drives are considered to be more reliable and have higher MTBF. In practice, stability is achieved more due to the checksum verification function. SATA drives, on the other hand, suffer from “silent errors” when data is partially written or damaged, which leads to the appearance of bad sectors.
The main advantage of SAS also contributes to the fault tolerance of the system - two duplex ports, allowing you to connect one device via two channels. In this case, information exchange will be carried out simultaneously in both directions, and reliability is ensured by Multipath I/O technology (two controllers protect each other and share the load). The queue of marked commands is built up to a depth of 256. Most SATA drives have one half-duplex port, and the queue depth using NCQ technology is no more than 32.
The SAS interface requires the use of cables up to 10 m long. Up to 255 devices can be connected to one port via expanders. SATA is limited to 1 m (2 m for eSATA), and only supports one point-to-point connection.
Prospects for further development are where the difference between SAS and SATA is also felt quite acutely. The throughput of the SAS interface reaches 12 Gbit/s, and manufacturers are announcing support for data transfer rates of 24 Gbit/s. The latest revision of SATA stopped at 6 Gbit/s and will not evolve in this regard.
SATA drives, in terms of the cost of 1 GB, have a very attractive price tag. In systems where the speed of data access is not critical and the volume of stored information is large, it is advisable to use them.
Table
| SAS | SATA |
| For server systems | Mainly for desktop and mobile systems |
| Uses the SCSI command set | Uses the ATA command set |
| Minimum HDD spindle speed 7200 RPM, maximum – 15000 RPM | Minimum 5400 RPM, maximum 7200 RPM |
| Supports technology for checking checksums when writing data | A large percentage of errors and bad sectors |
| Two full duplex ports | One half duplex port |
| Multipath I/O supported | Point-to-point connection |
| Command queue up to 256 | Team queue up to 32 |
| Cables up to 10 m can be used | Cable length no more than 1 m |
| Bus throughput up to 12 Gbit/s (in the future – 24 Gbit/s) | Bandwidth 6 Gbps (SATA III) |
| The cost of drives is higher, sometimes significantly | Cheaper in terms of price per 1 GB |
If your computer has a couple of drives, connecting them is simple. But if you want a lot of disks, peculiarities arise. On the KDPV SAS cable from Ali, which had already slipped through in the past, was so unexpectedly warmly received by the community. Thank you, comrades. I will try to touch on a topic that is potentially useful to a slightly wider circle. Although specific. I'll start with this cable and the required program, but only for starters. Different pieces of the puzzle have to be assembled in different places.
I would like to warn you right away that the text is dense and quite heavy. It’s certainly not necessary to force yourself to read and understand all of this. Lots of pictures!
Some people say 9 bucks for a dumb cable? What to do, this is used extremely rarely in everyday life, and for industrial items the circulation is lower and the prices are higher. They can charge you a hundred or two bucks for a complex SAS cable without blinking an eye. So the Chinese are reducing it even more :)
Delivery and packaging
Ordered May 6, 2017, received May 17 - just a rocket. There was a track.An ordinary gray bag with one more inside - quite enough, the goods are not fragile.
Specification
Female-male SFF-8482 SAS 29 pin cable.Length 50 cm
Net weight 66 g
Seller's picture 
Real appearance, as you can see, it’s different 
For the extra plastic, the seller received 4 stars instead of 5, but it does not affect performance.
About SAS and SATA connectors
What is SFF-8482 and what is it eaten with? Firstly, this is the most popular connector on SAS devices (), for example, on my tape drive
And the SFF-8482 fits perfectly on a SATA drive (but not vice versa) 
Compare, SATA has a gap between data and power. And at SAS it is filled with plastic. Therefore, the SATA connector will not fit on the SAS device.
Of course, this makes sense. The SAS and SATA signals are different. And the SATA controller will not be able to work with the SAS device. A SAS controller will be able to do both (although there is advice not to mix under certain circumstances, which are unlikely to be real at home)
SAS controllers and expanders
So what, the reader will ask. What do I gain from this compatibility? SATA controllers are enough for me!The real truth! If it’s enough, you can stop reading at this point. The question was what to do if there are a LOT of disks?
This is what a simple SAS controller looks like from my zip - DELL H200. 
Mine is stitched in HBA, that is, all axis disks are visible separately
And this is an ancient SAS RAID HP 
In both we see internal connectors (called sff 8087 or, more often, miniSAS) and one external connector - sff 8088
How many drives can be connected to one miniSAS? The answer depends. Blunt cable - 4 pieces, that is, 8 for such a controller. The cable from my spare parts looks like this 
At one end there is miniSAS, at the other there are 4 pieces of SATA (and another connector, more about it below)
But you can take a miniSAS-miniSAS cable and connect it to an expander, that is, a port multiplier. And the controller will handle up to 256 (two hundred and fifty-six) disks. Moreover, the channel speed is enough for dozens of disks - for sure.
The expander as a separate card looks, for example, like my Chenbro 
Or it can be soldered onto a disk cage. Then only one miniSAS channel can go into it (or maybe more). These are the cables. 
Agree, cable management is somewhat simplified :)
Baskets
It’s clear that disks can work just fine without special baskets. But sometimes baskets can be useful.This is what a SATA basket looks like old model Supermicro. You can find it for 1000 rubles, but more likely for 5+ thousand. 
Her disc tray 
View from the inside, you can see that there are SATA connectors. 
If the SAS basket is even better, less wires. If it's SCSI or FC, you won't be able to use it. I took one 19" FC for testing - it didn’t do anything useful. However, there was scrap non-ferrous metal almost worth the money for which I bought it. 
Rear view, we see 4 SATA, 2 MOLEX and the same port that was on the cable. Designed to control LED disk activity.
This is what one of the simplest baskets looks like (there are many different models, but similar) 
These are the ones they don't sell anymore, so the details aren't important. Just a piece of metal with shock absorbers and a Carlson in front.
This is what it looked like in 2013: 
The cardboard crutch at the bottom and the third basket were only for the moment for transferring data from 2T disks to 4T. Since then it has been working 24/7.
I have SAS+SATA
More precisely, it worked before I needed to connect the tape drive. First of all, I plugged in a second SAS controller, bought a miniSAS cable to sff 8482, something like this
And turned it on. Everything worked, but in 24/7 mode, every watt costs money. I was looking for adapters from sff 8482 to SATA, but the solution turned out to be even simpler. You remember that a SATA drive is connected to a SAS sff 8482? 
Now I also remember, but then I was stupid for a couple of months :) And then I took out the extra controller, switched one of the drives to the chipset SATA port, the other three to sff 8482. I had to change the power connection, there was a Molex-SATA splitter, I had to buy it on Ali Molex - lots of Molex. Like this 
, Everything is fine.
And the tape drive moved to another building using the monitored cable. But this is a separate story, and, guard, I feel tired :)
Where is the best place to look for all this?
Prices for new server hardware for the home are prohibitive. So used, including from spare parts from equipment being decommissioned.Cables can be found locally. For comparable money on e-bay. On Ali - somewhat less likely, but there are exceptions - I bought it.
Controllers- primarily on e-bay, and from Europe. It is possible from the USA, it is much cheaper there if you somehow solve the delivery issue. You can find it in your homeland - Avito. (On a lump - expensive). It is very dangerous to buy in China. Lots of complaints about fakes from the rejects. Sometimes it works, sometimes it doesn't. You can't prove anything to anyone.
Baskets It makes more sense to look locally. There are even options for the simplest baskets - buying new ones. Simple baskets without electronics can be taken in China and Europe and at flea markets. Baskets with expanders - see the paragraph about controllers.
IMPORTANT Getting confused is easier than getting lost in the forest. Consult the forum. SAS comes in different sizes - 3, 6 and 12 Gb/s. Some controllers are made so that they can be used with desktop hardware, others are not, and others will not survive anywhere except the mother of the native manufacturer. And so on.
On my trunk I'm MikeMac
PS If for you this became a speech by Captain Obvious, I apologize for wasting time.
If this is bullshit, then my sincere apologies. It’s difficult to balance; everyone has their own wants, objectives and initial ones.
Introduction
Look at modern motherboards (or even some older platforms). Do they require a special RAID controller? Most motherboards have three gigabit SATA ports, as well as audio jacks and network adapters. Majority modern chipsets, such as AMD A75 And Intel Z68, have support for SATA 6 Gb/s. With such support from the chipset, powerful processor and the availability of I/O ports, do you need additional cards for storage systems and a separate controller?
In most cases, ordinary users can create RAID 0, 1, 5 and even 10 arrays using the built-in SATA ports on the motherboard and special software, and can achieve very high performance. But in cases where a more complex RAID level is required - 30, 50 or 60 - more high level disk management or scalability, then the controllers on the chipset may not cope with the situation. In such cases, professional-grade solutions are needed.
In such cases, you are no longer limited to SATA storage systems. A large number of dedicated cards provide support for SAS (Serial-Attached SCSI) or Fiber Channel (FC) drives, each of these interfaces bringing with them unique advantages.
SAS and FC for professional RAID solutions
Each of the three interfaces (SATA, SAS and FC) has its pros and cons; none of them can be unconditionally called the best. Strengths The benefits of SATA-based drives are high capacity and low price, combined with high data transfer rates. SAS drives are renowned for their reliability, scalability, and high I/O speeds. FC storage systems provide constant and very high speed data transmission. Some companies still use Ultra SCSI solutions, although they can only handle up to 16 devices (one controller and 15 drives). Moreover, the bandwidth in this case does not exceed 320 MB/s (in the case of Ultra-320 SCSI), which cannot compete with more modern solutions.
Ultra SCSI is the standard for professional enterprise storage solutions. However, SAS is becoming increasingly popular because it offers not only significantly more bandwidth, but also greater flexibility when working with mixed SAS/SATA systems, allowing you to optimize cost, performance, availability and capacity even on a single JBOD (set of disks). In addition, many SAS disks have two ports for redundancy purposes. If one controller card fails, switching the drive to another controller avoids failure of the entire system. Thus, SAS ensures high reliability of the entire system.
Moreover, SAS is not only a point-to-point protocol for connecting the controller and storage device. It supports up to 255 storage devices per SAS port when using an expander. Using a two-tier SAS expander design, it is theoretically possible to attach 255 x 255 (or slightly more than 65,000) storage devices to a single SAS link, assuming the controller is capable of supporting such a large number of devices.
Adaptec, Areca, HighPoint and LSI: tests of four SAS RAID controllers
In this comparison test, we examine the performance of modern SAS RAID controllers, which are represented by four products: Adaptec RAID 6805, Areca ARC-1880i, HighPoint RocketRAID 2720SGL and LSI MegaRAID 9265-8i.
Why SAS and not FC? On the one hand, SAS is the most interesting and relevant architecture today. It provides features such as zoning, which is very attractive to professional users. On the other hand, the role of FC in the professional market is declining, and some analysts are even predicting its complete demise based on the number of hard drives shipped. According to IDC experts, the future of FC looks quite bleak, but SAS hard drives can claim 72% of the enterprise hard drive market in 2014.
Adaptec RAID 6805
Chip manufacturer PMC-Sierra launched the "Adaptec by PMC" series of RAID 6 controller family in late 2010. The 6 series controller cards are based on a dual-core SRC 8x6 GB ROC (RAID on Chip) controller that supports 512 MB cache and up to 6 Gbps per SAS port. There are three low-profile models: the Adaptec RAID 6405 (4 internal ports), the Adaptec RAID 6445 (4 internal and 4 external ports), and the one we tested, the Adaptec RAID 6805 with eight internal ports, which costs about $460.
All models support JBOD and RAID of all levels - 0, 1, 1E, 5, 5EE, 6, 10, 50 and 60.
Connected to the system via x8 interface PCI Express 2.0, Adaptec RAID 6805 supports up to 256 devices via SAS expander. In accordance with the manufacturer's specifications, the stable data transfer rate to the system can reach 2 GB/s, and the peak speed can reach 4.8 GB/s on the aggregated SAS port and 4 GB/s on the PCI Express interface - the last digit is the maximum theoretically possible value for PCI buses Express 2.0x.
ZMCP without support required
Our review unit came with the Adaptec Falsh Module 600, which uses Zero Maintenance Cache Protection (ZMCP) and does not use the legacy Battery Backup Unit (BBU). The ZMCP module is a block with a 4 GB NAND flash chip that is used for Reserve copy controller cache memory in case of power failure.
Because copying from cache to flash is so fast, Adaptec uses capacitors to support power rather than batteries. The advantage of capacitors is that they can last as long as the cards themselves, whereas backup batteries should be replaced every few years. In addition, once data is copied to flash memory, it can remain there for several years. By comparison, you typically have about three days of data storage before the cached information is lost, forcing you to rush through data recovery. As the name suggests, ZMCP is a solution that can withstand power failures.
Performance
The Adaptec RAID 6805 in RAID 0 mode loses in our streaming read/write tests. In addition, RAID 0 is not a typical case for a business that needs data protection (although it may well be used for a video rendering workstation). Sequential reading is at a speed of 640 MB/s, and sequential writing is at 680 MB/s. Based on these two parameters, the LSI MegaRAID 9265-8i takes the top position in our tests. The Adaptec RAID 6805 performs better in the RAID 5, 6 and 10 tests, but is not an absolute leader. In an SSD-only configuration, the Adaptec controller achieves speeds of up to 530 MB/s, but is outperformed by the Areca and LSI controllers.
The Adaptec card automatically recognizes what it calls a HybridRaid configuration, which consists of a mixture of HDDs and SSDs, offering RAID levels 1 to 10 in such a configuration. This card outperforms its competitors thanks to its special read/write algorithms. They automatically route read operations to the SSD and write operations to both the hard drive and the SSD. Thus, reading operations will work as in a system with only SSDs, and writing will work no worse than in a system with hard drives.
However, our test results do not reflect the theoretical situation. With the exception of the Web server benchmarks, where the data transfer rate for the hybrid system works, the hybrid SSD system and hard drives cannot approach the speed of an SSD-only system.
The Adaptec controller performs much better in the HDD I/O performance test. Regardless of the type of benchmark (database, file server, Web server or workstation), the RAID 6805 controller is neck and neck with the Areca ARC-1880i and LSI MegaRAID 9265-8i, and takes first or second place. Only the HighPoint RocketRAID 2720SGL leads the I/O test. If you replace hard drives with SSDs, then the LSI MegaRAID 9265-8i significantly outperforms the other three controllers.
Installing software and setting up RAID
Adaptec and LSI have well-organized, easy-to-use RAID management tools. Management tools allow administrators to gain remote access to controllers via the network.
Array installation
Areca ARC-188oi
Areca is also introducing the ARC-1880 series into the 6 Gb/s SAS RAID controller market segment. According to the manufacturer, target applications range from NAS applications and storage servers to high-performance computing, backup, security and cloud computing.
Tested samples of the ARC-1880i with eight external SAS ports and eight PCI Express 2.0 interface lanes can be purchased for $580. The low-profile card, which is the only card in our set with an active cooler, is built around an 800 MHz ROC with support for a 512 MB DDR2-800 data cache. Using SAS expanders, the Areca ARC-1880i supports up to 128 storage systems. To preserve cache contents during a power failure, a battery power supply can be optionally added to the system.
In addition to single mode and JBOD, the controller supports RAID levels 0, 1, 1E, 3, 5, 6, 10, 30, 50 and 60.
Performance
The Areca ARC-1880i performs well in RAID 0 read/write tests, achieving 960 MB/s read and 900 MB/s write. Only the LSI MegaRAID 9265-8i is faster in this particular test. The Areca controller does not disappoint in other benchmarks either. Both when working with hard drives and SSDs, this controller always actively competes with the test winners. Although the Areca controller was the leader in only one benchmark (sequential read in RAID 10), it showed very high results, for example, a read speed of 793 MB / s, while the fastest competitor, the LSI MegaRAID 9265-8i, showed only 572 MB/s
However, sequential transmission of information is only one part of the picture. The second is I/O performance. The Areca ARC-1880i performs brilliantly here too, competing on equal terms with the Adaptec RAID 6805 and LSI MegaRAID 9265-8i. Similar to its victory in the data transfer speed benchmark, the Areca controller also won one of the input/output tests - the Web server benchmark. The Areca controller dominates the Web server benchmark at RAID levels 0, 5 and 6, and for RAID 10 the Adaptec 6805 takes the lead, leaving the Areca controller in second place with a slight lag.
Web GUI and Settings
Like the HighPoint RocketRAID 2720SGL, the Areca ARC-1880i is conveniently managed via a Web interface and is easy to configure.
Array installation
HighPoint RocketRAID 2720SGL
The HighPoint RocketRAID 2720SGL is a SAS RAID controller with eight internal SATA/SAS ports, each supporting 6 Gbps. According to the manufacturer, this low-profile card is aimed at storage systems for small and medium-sized businesses and workstations. The key component of the card is the Marvell 9485 RAID controller. Key competitive advantages– small size and PCIe 2.0 interface for 8 lanes.
In addition to JBOD, the card supports RAID 0, 1, 5, 6, 10 and 50.
In addition to the model that was tested in our tests, there are 4 more models in the low-profile HighPoint 2700 series: RocketRAID 2710, RocketRAID 2711, RocketRAID 2721 and RocketRAID 2722, which mainly differ in the types of ports (internal/external) and their number ( from 4 to 8). Our tests used the cheapest of these RAID controllers, the RocketRAID 2720SGL ($170). All cables to the controller are purchased separately.
Performance
When sequentially reading/writing to a RAID 0 array consisting of eight Fujitsu MBA3147RC drives, the HighPoint RocketRAID 2720SGL achieves an excellent read speed of 971 MB/s, second only to the LSI MegaRAID 9265-8i. The write speed of 697 MB/s isn't quite as fast, but it's still superior to the write speed of the Adaptec RAID 6805. The RocketRAID 2720SGL also delivers a wide variety of results. It outperforms other cards when running RAID 5 and 6, but with RAID 10 read speeds drop to 485 MB/s, the lowest of the four samples tested. Sequential write speed in RAID 10 is even worse - only 198 MB/s.
This controller is clearly not made for SSD. The read speed here reaches 332 MB/s, and the write speed is 273 MB/s. Even Adaptec RAID 6805, which is also not very good at working with SSDs, shows twice top scores. Therefore, HighPoint is not a competitor to two cards that work really well with SSDs: the Areca ARC-1880i and the LSI MegaRAID 9265-8i - they are at least three times faster.
We've said everything good we could say about HighPoint's performance in I/O mode. However, the RocketRAID 2720SGL ranks last in our tests across all four Iometer benchmarks. The HighPoint controller is quite competitive with other cards when working with the Web server benchmark, but significantly loses to its competitors in the other three benchmarks. This becomes apparent in the SSD tests, where the RocketRAID 2720SGL clearly demonstrates that it is not optimized for SSD performance. It clearly doesn't take full advantage of SSDs over HDDs. For example, the RocketRAID 2720SGL achieves 17,378 IOPs in the database benchmark, while the LSI MegaRAID 9265-8i outperforms it by four times, delivering 75,037 IOPs.
Web GUI and array settings
The RocketRAID 2720SGL web interface is convenient and easy to use. All RAID settings are easy to set.
Array installation
LSI MegaRAID 9265-8i
LSI positions the MegaRAID 9265-8i as a device for the small and medium business market. This card is suitable for providing reliability in clouds and other business applications. The MegaRAID 9265-8i is one of the more expensive controllers in our test (it costs $630), but as the test shows, this money is paid for its real advantages. Before we present the test results, let's discuss technical features these controllers and software applications FastPath and CacheCade.
The LSI MegaRAID 9265-8i uses a dual-core LSI SAS2208 ROC using an eight-lane PCIe 2.0 interface. The number 8 at the end of the device name means the presence of eight internal SATA/SAS ports, each of which supports a speed of 6 Gbps. Up to 128 storage devices can be connected to the controller via SAS expanders. The LSI card contains 1 GB of DDR3-1333 cache and supports RAID levels 0, 1, 5, 6, 10 and 60.
Setting up software and RAID, FastPath and CacheCade
LSI claims that FastPath can significantly speed up I/O systems when connecting SSDs. According to LSI experts, FastPath works with any SSD, significantly increasing the write/read performance of an SSD-based RAID array: 2.5 times when writing and 2 times when reading, reaching 465,000 IOPS. We were unable to verify this figure. However, this card was able to get the most out of five SSDs without using FastPath.
The next application for MegaRAID 9265-8i is called CacheCade. With it, you can use one SSD as cache memory for an array of hard drives. According to LSI experts, this can speed up the reading process by a factor of 50, depending on the size of the data in question, the application and the method of use. We tried this application on RAID array 5, consisting of 7 hard drives and one SSD (SSD was used for cache). Compared to a RAID 5 system of 8 hard drives, it became clear that CacheCade not only improves I/O speed, but also overall performance (more as the amount of constantly used data decreases). For testing, we used 25 GB of data and obtained 3877 IOPS per Iometer in the Web server template, while a regular hard drive array only allowed 894 IOPS.
Performance
In the end, it turns out that the LSI MegaRAID 9265-8i is the fastest I/O controller of all the SAS RAID controllers in this review. However, during sequential read/write operations, the controller exhibits average performance because its sequential performance is highly dependent on the RAID level you are using. When testing the hard drive at RAID 0 level, we get a sequential read speed of 1080 MB/s (which is significantly higher than the competition). The sequential write speed at RAID 0 level is 927 MB/s, which is also higher than that of competitors. But for RAID 5 and 6, LSI controllers are inferior to all their competitors, surpassing them only in RAID 10. In the SSD RAID test, the LSI MegaRAID 9265-8i demonstrates the best sequential write performance (752 MB/s) and only the Areca ARC-1880i beats it according to sequential reading parameters.
If you're looking for an SSD-focused RAID controller with high I/O performance, the LSI controller is the winner. With few exceptions, it ranks first in our I/O tests for file server, Web server, and workstation workloads. When your RAID array consists of SSDs, LSI's competitors can't match it. For example, in the workstation benchmark, the MegaRAID 9265-8i reaches 70,172 IOPS, while the Areca ARC-1880i, which is in second place, is almost two times inferior to it - 36,975 IOPS.
RAID software and array installation
As with Adaptec, LSI has convenient tools to manage a RAID array via a controller. Here are some screenshots:
Software for CacheCade
RAID software
Array installation
Comparison table and test bench configuration
| Manufacturer | Adaptec | Areca |
| Product | RAID 6805 | ARC-1880i |
| Form factor | Low profile MD2 | Low profile MD2 |
| Number of SAS ports | 8 | 8 |
| 6 Gbps (SAS 2.0) | 6 Gbps (SAS 2.0) | |
| Internal SAS ports | 2xSFF-8087 | 2xSFF-8087 |
| External SAS ports | No | No |
| Cache memory | 512 MB DDR2-667 | 512 MB DDR2-800 |
| Main interface | PCIe 2.0 (x8) | PCIe 2.0 (x8) |
| XOR and clock speed | PMC-Sierra PM8013/No data | No data/800 MHz |
| Supported RAID Levels | 0, 1, 1E, 5, 5EE, 6, 10, 50, 60 | 0, 1, 1E, 3, 5, 6, 10, 30, 50, 60 |
| Windows 7 Windows Server 2008/2008 R2, Windows Server 2003/2003 R2, Windows Vista, VMware ESX Classic 4.x (vSphere), Red Hat Enterprise Linux (RHEL), SUSE Linux Enterprise Server (SLES), Sun Solaris 10 x86, FreeBSD, Debian Linux, Ubuntu Linux | Windows 7/2008/Vista/XP/2003, Linux, FreeBSD, Solaris 10/11 x86/x86_64, Mac OS X 10.4.x/10.5.x/10.6.x, VMware 4.x | |
| Battery | No | Optional |
| Fan | No | Eat |
| Manufacturer | HighPoint | LSI |
| Product | RocketRAID 2720SGL | MegaRAID 9265-8i |
| Form factor | Low profile MD2 | Low profile MD2 |
| Number of SAS ports | 8 | 8 |
| SAS bandwidth per port | 6 Gbps (SAS 2.0) | 6 Gbps (SAS 2.0) |
| Internal SAS ports | 2xSFF-8087 | 2xSFF-8087 |
| External SAS ports | No | No |
| Cache memory | No data | 1 GB DDR3-1333 |
| Main interface | PCIe 2.0 (x8) | PCIe 2.0 (x8) |
| XOR and clock speed | Marvel 9485/No Data | LSI SAS2208/800 MHz |
| Supported RAID Levels | 0, 1, 5, 6, 10, 50 | 0, 1, 5, 6, 10, 60 |
| Supported Operating Systems | Windows 2000, XP, 2003, 2008, Vista, 7, RHEL/CentOS, SLES, OpenSuSE, Fedora Core, Debian, Ubuntu, FreeBSD bis 7.2 | Microsoft Windows Vista/2008/Server 2003/2000/XP, Linux, Solaris (x86), Netware, FreeBSD, Vmware |
| Battery | No | Optional |
| Fan | No | No |
Test configuration
We connected eight Fujitsu MBA3147RC SAS hard drives (each 147 GB) to RAID controllers and ran benchmarks for RAID levels 0, 5, 6 and 10. SSD tests were carried out with five Samsung SS1605 drives.
| Hardware | |
| CPU | Intel Core i7-920 (Bloomfield) 45 nm, 2.66 GHz, 8 MB shared L3 cache |
| Motherboard (LGA 1366) | Supermicro X8SAX, Revision: 1.0, Intel X58 + ICH10R chipset, BIOS: 1.0B |
| Controller | LSI MegaRAID 9280-24i4e Firmware: v12.12.0-0037 Driver: v4.32.0.64 |
| RAM | 3 x 1 GB DDR3-1333 Corsair CM3X1024-1333C9DHX |
| HDD | Seagate NL35 400 GB, ST3400832NS, 7200 rpm, SATA 1.5 Gbit/s, 8 MB cache |
| power unit | OCZ EliteXstream 800 W, OCZ800EXS-EU |
| Benchmarks | |
| Performance | CrystalDiskMark 3 |
| I/O Performance | Iometer 2006.07.27 File server Benchmark Web server Benchmark Database Benchmark Workstation Benchmark Streaming Reads Streaming Writes 4k Random Reads 4k Random Writes |
| Software and drivers | |
| operating system | Windows 7 Ultimate |
Test results
I/O performance in RAID 0 and 5
Benchmarks in RAID 0 show no significant difference between the RAID controllers, with the exception of the HighPoint RocketRAID 2720SGL.
The RAID 5 benchmark doesn't help the HighPoint controller regain its lost ground. Unlike the RAID 0 benchmark, all three faster controllers show their strengths and weaknesses more clearly here.
I/O performance in RAID 6 and 10
LSI has optimized its MegaRAID 9265 controller for database, file server and workstation workloads. All controllers pass the benchmark for the Web server well, demonstrating the same performance.
In RAID 10, Adaptec and LSI are competing for first place, with HighPoint RocketRAID 2720SGL coming in last.
SSD I/O Performance
The leader here is the LSI MegaRAID 9265, which takes advantage of all the advantages of solid-state storage systems.
Throughput in RAID 0, 5 and degraded RAID 5 mode
LSI MegaRAID 9265 easily leads in this benchmark. The Adaptec RAID 6805 lags far behind.
HighPoint RocketRAID 2720SGL without cache copes well with sequential operations in RAID 5. Other controllers are not much inferior to it.
Degraded RAID 5
Throughput in RAID 6, 10 and degraded RAID 6 mode
As with RAID 5, the HighPoint RocketRAID 2720SGL has the highest throughput for RAID 6, leaving the Areca ARC-1880i in second place. The impression is that the LSI MegaRAID 9265-8i simply does not like RAID 6.
Degraded RAID 6
Here the LSI MeagaRAID 9265-8i already shows itself in better light, although it skips ahead of the Areca ARC-1880i.
LSI CacheCade
What is the best 6 Gb/s SAS controller?
Overall, all four SAS RAID controllers we tested performed well. All have all the necessary functionality, and all of them can be successfully used in entry-level and mid-level servers. In addition to outstanding performance, they also have important features such as working in a mixed environment with support for SAS and SATA and scaling through SAS expanders. All four controllers support the SAS 2.0 standard, which increases throughput from 3 Gbps to 6 Gbps per port, and also introduces new features such as SAS zoning, which allows multiple controllers to access storage resources through a single SAS -expander.
Despite similar features such as a low-profile form factor, eight-lane PCI Express interface and eight SAS 2.0 ports, each controller has its own strengths and weak sides, analyzing which it is possible to give recommendations for their optimal use.
So, the fastest controller is the LSI MegaRAID 9265-8i, especially in terms of I/O throughput. Although it also has weaknesses, in particular, not very high performance in cases of RAID 5 and 6. MegaRAID 9265-8i leads in most benchmarks and is an excellent professional-level solution. The cost of this controller – $630 – is the highest, we should not forget about this either. But for that high price, you get a great controller that is ahead of its competitors, especially when dealing with SSDs. It also has excellent performance, which becomes especially valuable when connecting large-capacity storage systems. Moreover, you can increase the performance of the LSI MegaRAID 9265-8i using FastPath or CacheCade, for which you will naturally have to pay extra.
The Adaptec RAID 6805 and Areca ARC-1880i controllers demonstrate the same performance and are very similar in price ($460 and $540). Both work well, as shown by various benchmarks. The Adaptec controller performs slightly better than the Areca controller and also offers the sought-after ZMCP (Zero Maintenance Cache Protection) feature, which replaces conventional power failure redundancy and allows operations to continue.
The HighPoint RocketRAID 2720SGL retails for just $170, which is much cheaper than the other three controllers we tested. The performance of this controller is quite adequate if you are working with regular drives, although it is not as good as the Adaptec or Areca controllers. And you should not use this controller to work with SSD.
This article will talk about what allows you to connect HDD to the computer, namely, about the interface hard drive. More precisely, about hard drive interfaces, because a great many technologies have been invented for connecting these devices throughout their existence, and the abundance of standards in this area can confuse an inexperienced user. However, first things first.
Hard drive interfaces (or strictly speaking, interfaces external drives, since they can be used not only by , but also by other types of drives, for example, drives for optical disks) are designed to exchange information between these devices external memory And motherboard. Hard drive interfaces, no less than the physical parameters of the drives, affect many of the operating characteristics of the drives and their performance. In particular, drive interfaces determine such parameters as the speed of data exchange between the hard drive and the motherboard, the number of devices that can be connected to the computer, the ability to create disk arrays, the possibility of hot plugging, support for NCQ and AHCI technologies, etc. . It also depends on the hard drive interface which cable, cord or adapter you will need to connect it to the motherboard.
SCSI - Small Computer System Interface
The SCSI interface is one of the oldest interfaces designed for connecting storage devices in personal computers. This standard appeared in the early 1980s. One of its developers was Alan Shugart, also known as the inventor of the floppy disk drive.
Appearance of the SCSI interface on the board and the cable connecting to it
The SCSI standard (traditionally this abbreviation is read in Russian transcription as “skazi”) was originally intended for use in personal computers, as evidenced by the very name of the format - Small Computer System Interface, or system interface for small computers. However, it so happened that the drives of this type were used mainly in top-class personal computers, and subsequently in servers. This was due to the fact that, despite the successful architecture and a wide set of commands, the technical implementation of the interface was quite complex and was not affordable for mass PCs.
However, this standard had a number of features that were not available for other types of interfaces. For example, the cord for connecting Small Computer System Interface devices can have a maximum length of 12 m, and the data transfer speed can be 640 MB/s.
Like the IDE interface that appeared a little later, the SCSI interface is parallel. This means that the interface uses buses that transmit information over several conductors. This feature was one of the limiting factors for the development of the standard, and therefore a more advanced, consistent SAS standard (from Serial Attached SCSI) was developed as its replacement.
SAS - Serial Attached SCSI
This is what the SAS server disk interface looks like
Serial Attached SCSI was developed as an improvement to the rather old Small Computers System Interface for connecting hard drives. Despite the fact that Serial Attached SCSI uses the main advantages of its predecessor, it nevertheless has many advantages. Among them it is worth noting the following:
- Use of a common bus by all devices.
- The serial communication protocol used by SAS allows for fewer signal lines to be used.
- There is no need for bus termination.
- Virtually unlimited number of connected devices.
- Higher throughput(up to 12 Gbit/s). Future implementations of the SAS protocol are expected to support data transfer rates of up to 24 Gbit/s.
- Possibility of connecting drives with Serial ATA interface to the SAS controller.
As a rule, Serial Attached SCSI systems are built on the basis of several components. The main components include:
- Target devices. This category includes the actual drives or disk arrays.
- Initiators are chips designed to generate requests to target devices.
- Data delivery system - cables connecting target devices and initiators
Serial Attached SCSI connectors come in different shapes and sizes, depending on the type (external or internal) and SAS versions. Below are the SFF-8482 internal connector and the SFF-8644 external connector designed for SAS-3:
On the left is an internal SAS connector SFF-8482; On the right is an external SAS SFF-8644 connector with a cable.
A few examples of the appearance of SAS cords and adapters: HD-Mini SAS cord and SAS-Serial ATA adapter cord.
On the left is the HD Mini SAS cable; On the right is an adapter cable from SAS to Serial ATA.
Firewire - IEEE 1394
Today you can often find hard disks with Firewire interface. Although you can connect any types to your computer via the Firewire interface peripheral devices, and it cannot be called a specialized interface designed exclusively for connecting hard drives, however, Firewire has a number of features that make it extremely convenient for this purpose.
FireWire - IEEE 1394 - view on a laptop
The Firewire interface was developed in the mid-1990s. The development began with the well-known company Apple, which needed its own bus, different from USB, for connecting peripheral equipment, primarily multimedia. The specification describing the operation of the Firewire bus is called IEEE 1394.
Firewire is one of the most commonly used high-speed serial external bus formats today. The main features of the standard include:
- Possibility of hot connection of devices.
- Open bus architecture.
- Flexible topology for connecting devices.
- Data transfer speeds vary widely – from 100 to 3200 Mbit/s.
- The ability to transfer data between devices without a computer.
- Possibility of organization local networks using a tire.
- Power transmission via bus.
- A large number of connected devices (up to 63).
To connect hard drives (usually via external hard drive enclosures) via the Firewire bus, you usually use special standard SBP-2, using the Small Computers System Interface protocol command set. It is possible to connect Firewire devices to a regular USB connector, but this requires a special adapter.
IDE - Integrated Drive Electronics
The abbreviation IDE is undoubtedly known to most users. personal computers. Interface standard for connecting hard drives IDE drives was developed by a well-known hard drive manufacturing company - Western Digital. The advantage of IDE over other interfaces that existed at the time, in particular the Small Computers System Interface, as well as the ST-506 standard, was that there was no need to install a hard drive controller on the motherboard. The IDE standard implied installing a drive controller on the drive itself, and only a host interface adapter for connecting IDE drives remained on the motherboard.
IDE interface on motherboard
This innovation has improved the operating parameters of the IDE drive due to the fact that the distance between the controller and the drive itself has been reduced. In addition, installing an IDE controller inside the hard drive case made it possible to somewhat simplify both motherboards and the production of hard drives themselves, since the technology gave freedom to manufacturers in terms of optimal organization of the logic of the drive.
The new technology was initially called Integrated Drive Electronics. Subsequently, a standard was developed to describe it, called ATA. This name is derived from the last part of the name of the PC/AT family of computers by adding the word Attachment.
For connecting hard drive or other device, such as an optical drive that supports Integrated Drive Electronics technology, to the motherboard uses a special IDE cable. Since ATA refers to parallel interfaces (therefore it is also called Parallel ATA or PATA), that is, interfaces that provide simultaneous data transmission over several lines, its data cable has a large number of conductors (usually 40, and in latest versions protocol, it was possible to use an 80-core cable). Regular data cable for this standard has a flat and wide appearance, but there are also round cables. The power cable for Parallel ATA drives has a 4-pin connector and is connected to the computer's power supply.
Below are examples of IDE cable and round PATA data cable:
Appearance of the interface cable: on the left - flat, on the right in a round braid - PATA or IDE.
Thanks to the comparative low cost of Parallel ATA drives, the ease of implementation of the interface on the motherboard, as well as the ease of installation and configuration of PATA devices for the user, Integrated Drive Electronics type drives have for a long time pushed out devices of other interface types from the market of hard drives for budget-level personal computers.
However, the PATA standard also has a number of disadvantages. First of all, this is a limitation on the length that a Parallel ATA data cable can have - no more than 0.5 m. In addition, the parallel organization of the interface imposes a number of restrictions on maximum speed data transmission. It does not support the PATA standard and many of the advanced features that other types of interfaces have, such as hot plugging of devices.
SATA - Serial ATA
View of the SATA interface on the motherboard
The SATA (Serial ATA) interface, as the name suggests, is an improvement over ATA. This improvement consists, first of all, in converting the traditional parallel ATA (Parallel ATA) into a serial interface. However, the differences between the Serial ATA standard and the traditional one are not limited to this. In addition to changing the data transmission type from parallel to serial, the data and power connectors also changed.
Below is the SATA data cable:
Data cable for SATA interface
This made it possible to use a much longer cord and increase the data transfer speed. However, the downside was the fact that PATA devices, which were present on the market in huge quantities before the advent of SATA, became impossible to connect directly to the new connectors. True, most new motherboards still have old connectors and support connecting older devices. However, the reverse operation - connecting a new type of drive to an old motherboard usually causes much more problems. For this operation, the user usually requires a Serial ATA to PATA adapter. The power cable adapter usually has a relatively simple design.
Serial ATA to PATA power adapter:
On the left is a general view of the cable; On the right is an enlarged view of the PATA and Serial ATA connectors
However, the situation is more complicated with such a device as an adapter for connecting a serial interface device to a connector for parallel interface. Typically, an adapter of this type is made in the form of a small microcircuit.
Appearance of a universal bidirectional adapter between SATA - IDE interfaces
Currently, the Serial ATA interface has practically replaced Parallel ATA, and PATA drives can now be found mainly only in fairly old computers. Another feature of the new standard that ensured its wide popularity was support.
Type of adapter from IDE to SATA
You can tell us a little more about NCQ technology. The main advantage of NCQ is that it allows you to use ideas that have long been implemented in the SCSI protocol. In particular, NCQ supports a system for sequencing read/write operations across multiple drives installed in a system. Thus, NCQ can significantly improve the performance of drives, especially hard drive arrays.
Type of adapter from SATA to IDE
To use NCQ, technology support is required from the hard drive as well as the host adapter motherboard. Almost all adapters that support AHCI also support NCQ. In addition, some older proprietary adapters also support NCQ. Also, for NCQ to work, it requires support from the operating system.
eSATA - External SATA
It is worth mentioning separately the eSATA (External SATA) format, which seemed promising at the time, but never became widespread. As you can guess from the name, eSATA is a type of Serial ATA designed for connecting exclusively external drives. The eSATA standard offers for external devices most of the capabilities of the standard one, i.e. internal Serial ATA, in particular, the same system of signals and commands and the same high speed.
eSATA connector on a laptop
However, eSATA also has some differences from the internal bus standard that gave birth to it. In particular, eSATA supports a longer data cable (up to 2 m) and also has higher power requirements for drives. Additionally, eSATA connectors are slightly different from standard Serial ATA connectors.
Compared to other external buses, such as USB and Firewire, eSATA, however, has one significant drawback. While these buses allow the device to be powered via the bus cable itself, the eSATA drive requires special connectors for power. Therefore, despite the relatively high data transfer speed, eSATA is currently not very popular as an interface for connecting external drives.
Conclusion
Information stored on a hard drive cannot become useful to the user or accessible to application programs until it is accessed CPU computer. Hard drive interfaces provide a means of communication between these drives and the motherboard. Today there are many various types hard drive interfaces, each of which has its own advantages, disadvantages and characteristics. We hope that the information provided in this article will be largely useful to the reader, because the choice of a modern hard drive is largely determined not only by its internal characteristics, such as capacity, cache memory, access and rotation speed, but also by the interface for which it was developed.
SAS (Serial Attached SCSI)- serial computer interface designed to connect various devices data storage, for example, and tape drives. SAS is designed to replace the parallel SCSI interface and uses the same SCSI command set.
SAS is backward compatible with the SATA interface: SATA II and SATA 6 Gb/s devices can be connected to a SAS controller, but SAS devices cannot be connected to a SATA controller. The latest SAS implementation provides data transfer speeds of up to 12Gbps per line. By 2017, the SAS specification is expected to appear with a data transfer rate of 24 Gbit/s
SAS combines the advantages of SCSI interfaces (deep command queue sorting, good scalability, high noise immunity, long maximum cable length) and Serial ATA (thin, flexible, cheap cables, hot pluggability, point-to-point topology, allowing for greater performance in complex environments). configurations) with new unique capabilities - such as an advanced connection topology using hubs called SAS expanders (SAS expanders), connecting two SAS channels to one (both to increase reliability and performance), working on one disk as with SAS and SATA interface.
In combination with the new addressing system, this allows you to connect up to 128 devices per port and have up to 16256 devices on the controller, without requiring any manipulation of jumpers, etc. The 2 Terabyte limit on the size of a logical device has been removed.
The maximum cable length between two SAS devices is 10 m when using passive copper cables.
Actually, the SAS data transfer protocol means three protocols at once - SSP (Serial SCSI Protocol), which ensures the transmission of SCSI commands, SMP (SCSI Management Protocol), which works with SCSI control commands and is responsible, for example, for interaction with SAS expanders, and STP (SATA Tunneled Protocol), which provides support for SATA devices.
Produced in this moment have internal connectors of the SFF-8643 type (can also be called mini SAS HD), but you can still find connectors of the SFF-8087 (mini SAS) type, which has 4 SAS channels.
The external interface option uses the SFF-8644 connector, but the SFF-8088 connector may still be available. It also supports four SAS channels.
SAS controllers are fully compatible with SATA drives and SATA cages/backplanes– connection is usually made using cables: . The cable looks something like this:
SFF-8643 -> 4 x SAS/SATA
Typically, SAS cages/backplanes have SATA connectors on the outside and you can always insert regular SATA drives into them, which is why they (such cages) are usually called SAS/SATA.
However, there are reversible versions of such a cable for connecting a backplane with internal SFF-8087 connectors to a SAS controller that has regular SATA connectors. Such cables are not interchangeable with each other.
SAS drives cannot be connected to a SATA controller or installed in a SATA cage/backplane.
To connect SAS drives to a controller with internal SFF-8643 or SFF-8087 connectors without using SAS cages, you must use a cable type SFF-8643->SFF-8482 or SFF-8087->SFF-8482, respectively.
Existing versions of the SAS interface (1.0, 2.0, and 3.0) are compatible with each other, that is, a SAS2.0 drive can be connected to a SAS 3.0 controller and vice versa. Besides future version 24 Gb/s will also be backwards compatible.
SAS Connector Types
| Image | Codename | Also known as | External/ interior |
Number of contacts | Number of devices |