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SAS Drives: Seagate Takes The Lead

Next-Generation SAS: 6 Gb/s Storage Hits The Enterprise
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The product situation is similar on the drive side. We’ve only received a few SAS 6 Gb/s drives from Seagate and one from Hitachi. No one else has provided any SAS 6 Gb/s hardware yet, but we know Fujitsu will follow soon. We’ll mention important performance data for the drives presented on this page, but save the full results for a forthcoming enterprise hard drive roundup.

Hitachi Ultrastar C10K300

Hitachi’s Ultrastar C10K300 is a 10,000 RPM, 2.5” enterprise hard drive with a SAS 6 Gb/s interface. It is currently the fastest drive in terms of peak throughput, reaching 341 MB/s with the help of 64MB cache memory. It also does well in our sequential throughput tests, exceeding 140 MB/s. Today, 147GB and 300GB capacities are available.

Savvio 15K.2 (147, 73GB)

Since the 2.5” form factor is seeing considerable growth due to higher storage densities, Seagate emphasizes its Savvio 2.5” enterprise drives. The 15,000 RPM Savvio 15K.2 is equipped with a SAS 6 Gb/s interface.

There are 73GB and 147GB capacity points available, both utilizing 16MB cache memory. Read/write seek times from 3.2 to 3.5 ms are very quick. This translates into an amazing 5.0 ms average read access time, and we measured a 307 MB/s interface throughput. Our h2benchw benchmark tracked a maximum sequential throughput performance of 160 MB/s, which is rather impressive for a 2.5” drive.

Savvio 10K.3 (300, 146GB)

The Savvio 10K.3 is the 10,000 RPM counterpart in Seagate’s 2.5” lineup. It is similar to Hitachi’s C10K300 in throughput but stays slightly behind at 130 versus 140 MB/s. Look for 300GB and 146GB capacities available now. While Hitachi relies on 64MB buffer memory, Seagate decided to stay with only 16MB. The Savvio 10K.3 isn’t the fastest when it comes to I/O performance, but it is one of the most efficient drives.

Cheetah 15K.7 (600, 450, 300GB)

The Cheetah 15K.7 is Seagate’s top performance model for the enterprise, delivering an amazing 200 MB/s throughput and access times that are almost at the level of 15,000 RPM, 2.5” drives. Those who want added capacity will appreciate the 3.5” 15K.7’s 300, 450, and 600GB models. Again, these feature only 16MB of cache, but this didn’t seem to hurt the Cheetah 15K.7’s performance capabilities.

Cheetah NS.2 10K (600, 450, 300GB)

Finally, the Cheetah NS.2 10K is a 3.5” 10,000 RPM drive for low-power, high-capacity applications.

There are 600GB and 450GB models available, both featuring 16MB cache and the SATA 6 Gb/s interface. There must be something to the low-power claims, as this is one of the coolest enterprise hard drives we’ve had on our test bench. The 160 MB/s maximum throughput impresses, and I/O performance still behaves well despite this drive’s efficiency ambitions.

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  • 0 Hide
    bunz_of_steel , August 31, 2009 1:17 PM
    Now I like this, can't wait to see it implemented on EMC & IBM platforms. And on the servers side I'd like to see some numbers on spec's and performance. Good article Patrick Schmid and Achim Roos! Next.... benchmark 2.5 vs 3.5 on enterprise systems and low budget small business ....yes???
  • 0 Hide
    Shadow703793 , August 31, 2009 3:32 PM
    SCSI is still not dead?!?!? :lol: 

    Joking aside, I wonder if any motherboard manufacture like ASUS will get this on their high end WS models (see P6T WS). And I wonder if they will make any SSDs using this for the server sector.
  • 0 Hide
    kittle , August 31, 2009 8:45 PM
    Shadow703793SCSI is still not dead?!?!? citation]
    no its not -- its a long death cause most scsi drives run forever. I have a bunch of scsi drives running on my systems at home and as much as Id like the performance boost of SAS or even Sata, the things just wont die.

    but 6g/b SAS looks to be the next upgrade step
  • -5 Hide
    falchard , August 31, 2009 10:07 PM
    6Gb for SAS is kind of pointless considering SAS drives only peak 100MB
  • 0 Hide
    rhodenator , September 1, 2009 7:11 PM
    On this page (http://www.tomshardware.com/reviews/sas-6gb-hdd,2392-8.html), I see that you stated "SAS 1.1 at 3 Gb/s (300 MB/s)"

    Well this has always confused me. If SAS 1.1 is 3 Gb/s, that would be 375 MB/sec (3 x 1000 to convert to 3000 Mb/sec and then 3000 \ 8 to convert to 375 MB/sec.)

    On the SAS Wiki site (http://en.wikipedia.org/wiki/Serial_Attached_SCSI) it shows 3 Gb/sec. However on the list of device speeds Wiki site (http://en.wikipedia.org/wiki/List_of_device_bandwidths) it shows 2.4 Gb/sec with a 300MB/sec. The only maximum that appears to stay the same is MB, which is 300. So is it really 2.4 Gb/sec or is it 3.0 Gb/sec really for SAS 1.1?

    Thanks!
  • 0 Hide
    jrst , September 2, 2009 4:12 AM
    @kittle -- Not to mention that SCSI is a protocol, not just a physical/electrical interface. SAS simply changes the physical/electrical interface, but the good old SCSI protocol is still in there (just like SATA still has ATA underneath).

    @falchard -- No, it's not pointless. A dedicated controller channel for every drive would be prohibitively expensive for large drive arrays (not to mention the cabling nightmare), which is why SAS (unlike SATA) allows for more complex topologies, not just point-to-point. When you put multiple drives/expanders on a channel, you can quickly hit SAS bus speed limits.

    @rhodenator -- SAS (like SATA) uses 8b/10b encoding. That is, 8 data bits end up as 10 bits on the wire (typical of high speed serial buses), so: 3.0Gbs wire * 8/10 encoding = 2.4Gbs data = 300MBs data.
  • 0 Hide
    JohnnyLucky , September 2, 2009 4:35 PM
    I bet the hardcore gamers are drooling at the prospect of SAS 6Gb/sec. Too bad they'll have to wait.
  • 0 Hide
    Anonymous , September 3, 2009 1:26 PM
    Actually, LSI was not 1st to market w/ 6g controllers. ATTO Tech was shipping their H6xx 6G HBAs months ago based on the PMC Sierra chip. Also HP has been shipping their 6G RAID controllers - P212 & P410 (also PMC Sierra chip) for a couple of months also. Granted LSI is the industry leader w/ SAS but has stumbled in execution of releasing 6G product.
  • 0 Hide
    s_a_r99 , September 3, 2009 1:59 PM
    Actually, LSI was not 1st to market w/ 6G SAS controllers. That distinction goes to ATTO Tech with their H6xx 6G HBA line up and HP for their 6G RAID controllers - P212 & P410. All of these are based on the PMC Sierra chipset. LSI has been stumbling to get 6G products out the door.
  • 0 Hide
    tygrus , September 7, 2009 4:28 AM
    re: rhodenator. As mentioned in the article; 8b/10b encoding means that 8bits data is encoded using 10bits accross the link. 3000Mb/10b = 300MB. Command and control overhead and processing delay further limits real world performance to about 270MB/s. I think someone managed over 580MB/s using the new 6Gb/s signalling and more data per transfer to reduce overhead (was that using SATA or SAS ?).


    re: falchard "..kind of pointless.." NO.
    "Build it and they will come". You have to start building the infrastructure and plan for the future otherwise it's pointless making the drives go faster. I want a server that in a few years time can take additional drives or replacements where performance boost is not nullified by slow IO bandwidth.

    It will take 12months after the standard's release to be more common as HBA, motherboard and drive designs are refreshed.

    SATA is no longer a 1-to-1 link and burst bandwidth is close to current limit.
    600MB/s means enough bandwidth to aggregate 4 of today's SAS HD per SAS port or maybe 2 SSD's. Within 2 years a single HD will exceed current limit and within 1 year SSD's will reach the new limit.