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SAS Storage: High-Performance Hard Drives

SAS Storage: High-Performance Hard Drives
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It’s amazing to see how quickly markets can change. There used to be a rather strict classification among enterprise, desktop and notebook drives, but while the desktop and notebook segments haven’t changed all that much, the enterprise space is undergoing huge changes, due to cost pressure on the one side and the flash memory threat on the other. Hitachi and Seagate have managed to show that modern 3.5” SAS hard drives can still make a pretty convincing argument, though.

SATA for Servers

The advent of Serial ATA moved high-end desktop drives into the enterprise space, because high-capacity SATA drives are powerful enough for near-line storage (that which does not require frequent access) while providing far more capacity than SCSI and SAS drives. Disk archiving and backup solutions are possible applications, and the significant cost savings can be invested into additional spare drives. Hitachi’s Ultrastar A7K1000 and Seagate’s Barracuda ES are examples of this drive breed.

2.5” for Servers

At the same time, a 2.5” form factor doesn’t necessarily imply a notebook drive anymore. In fact, smaller enterprise drives provide better efficiency. We already compared 10,000 RPM and 15,000 RPM 2.5” SAS drives to see how they measure up to their 3.5” brothers, and the result was obvious: 2.5” enterprise drives provide better efficiency and superior I/O performance within the space constraints in rackmount servers.

Flash for I/O

We also looked at flash versus conventional hard drives in RAID array configurations in the article Will SSDs Take Over the Enterprise?. While flash-based SSDs still don’t outperform all enterprise hard drives when it comes to throughput, they beat the hell out of mechanical drives in all I/O-intensive benchmarks. Servers with high I/O loads benefit tremendously from flash-based enterprise storage.

Hitachi and Seagate to the HDD Rescue

Obviously, the enterprise hard drive market is continuing to shrink, and there will only be a market for drives that combine high performance with high capacity. These will be able to counter flash SSDs in many application scenarios, while providing storage capacity that is more acceptable than the 32 or 64 GB available in the flash SSD product space today.

Hitachi’s Ultrastar 15K450 and the Seagate Cheetah 15K.6 are the latest 3.5” enterprise hard drive models, introducing capacities of up to 450 GB, and 15,000 RPM performance that actually manages to best even the fastest flash SSDs.

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  • -3 Hide
    tai_anjing_lu , August 26, 2008 8:00 AM
    Expensive price for such capacity. I prefer buying 2 x 500 GB or a terabyte for larger capacity.
  • 0 Hide
    somasaint , August 26, 2008 9:18 AM
    1x OCZ 64GB SATAII SSD = ~270$USD [pricewatch]

    or

    2x 15k_rpm Fujitsu SAS 73GB + Dell PERC 5i = ~200$USD [ebay]

    superior initial performance and incredible scalability and RAID options.

    the choice is obvious..
  • -3 Hide
    neiroatopelcc , August 26, 2008 9:20 AM
    This looks awesome! I wonder if one of those could replace my 3x WD Raptor 36 (striped) ; sas drives don't work on an ordinary ich9r controller do they?
  • -1 Hide
    somasaint , August 26, 2008 9:41 AM
    neiroatopelcc,

    sorry.. SAS requires an aggressive commitment. typically SAS
    controllers cards come in pci-x, but the dell perc 5i line can
    be found [ebay] in the pci-e version.. given your mainboard has
    a free pci-e 8x slot .. which usually means an SLI board.. or triple
    for those of you already running twin rigs. the benefits here being
    you can set your stripe size to 1mb.. and you get ddr256mb cache + BBU.

    here are my figures: via HDTach [raid-0: 73GB 15k sas fujitus + perc5i]
    http://img403.imageshack.us/img403/940/boredeq1.jpg
  • 0 Hide
    Turas , August 26, 2008 10:01 AM
    How about some sound tests? I have been debating these versus SSD since they were announced but was curious as to just how loud they were. You do mention you can easily hear it but it would be nice to get a sound reading from say 1 meter away or somethign like that. Also how hot are the drives getting? How much cooling will I need for these, especially with 3 or them in the box?

  • 0 Hide
    dangerous_23 , August 26, 2008 10:05 AM
    which would be better for a thin client server, SSDs or one of these SAS drives?
  • 1 Hide
    ceteras , August 26, 2008 10:38 AM
    http://www.vr-zone.com/articles/ASUS_Announced_P6T_Boards_For_Core_i7_Nehalem/5978.html

    ASUS Announced P6T Boards For Core i7 Nehalem

    SAS Support for Server-level Storage

    To match the supreme performance of the new platform, the ASUS P6T Deluxe will adopt the SAS (Serial Attached SCSI) controller to let users utilize SAS hard disks. These hard disks will provide higher data transmission speeds and better data storage reliability in comparison to current SATA interfaces; and could herald the start of a new standard for mainstream storage devices that caters to enterprise users. With this technological improvement, users will be able to connect 2 SAS hard disks to the P6T Deluxe without the need to purchase an extra SAS controller card. Performance-wise, an SAS hard disk gains a 39% improvement on PC Mark HDD Test benchmarks when comparing RAID 0 performances with SATA (supported by SB ICH10R) interfaces.
  • 0 Hide
    neiroatopelcc , August 26, 2008 10:57 AM
    Ouch that dell controller is expensive on ebay.de - It'd be cheaper to buy a (new) promise controller for 2 sas drives and a riser adapter to utilize it in a pcie slot (got a p35 board with a x4 link in a physical x16 socket), and get a sas drive or two.... that or wait till nehalem and pray for some other vendor (gigabyte, msi or abit) to implement a sas controller too. No way in hell I'll buy another asus board if I'm given a choice.
  • 6 Hide
    Anonymous , August 26, 2008 11:07 AM
    It would be nice if the article could actually put SSD numbers in the charts since they keep making reference to them in the text. Just the top 2-3 SSDs would be good so we don't have to manually hunt down other articles to really make the comparison.
  • 0 Hide
    wtg , August 26, 2008 1:40 PM
    I think I'll buy 2 Cheetah's and put them in a Raid 0 for my new video workstation !!!
  • 0 Hide
    martin0642 , August 26, 2008 1:57 PM
    Access time alone makes SSDs a better option, that and the noise, MTBF and RAID scaling.

    I've heard the "Clunk of Death" from head platters for the last time.
  • 1 Hide
    Bait , August 26, 2008 1:59 PM
    Has anyone looked at Compact Flash Cards as an alternative to the $1000 32GB SSD's? 32GB Compact Flash Cards (~$100) are cheap in comparison.
  • 0 Hide
    nbk_redspy , August 26, 2008 2:37 PM
    I agree, I expected to see the SSD numbers as well, but from the last couple of SSD articles, Tom's seemed to be a little behind on the latest SSD models.

    For example, using the OCZ Core when the superior Core II was commercially available.
  • 0 Hide
    Mathos , August 26, 2008 3:32 PM
    martin0642Access time alone makes SSDs a better option, that and the noise, MTBF and RAID scaling.I've heard the "Clunk of Death" from head platters for the last time.


    Yes instead of MTBF you have time before cells start dieing out from too many read write cycles.

    Noise is good though, less power usage is good, and IO performance as far as access times are an advantage.

    But the trade off is storage cap, huge price per gig difference. And things like that. I think the best option would be to make a hybrid drive. Things that need high I/O access speed stay on the flash drive, things that need mass storage go on the mechanical disk.
  • 0 Hide
    Anonymous , August 26, 2008 3:46 PM
    don't forget Intel's upcoming SSD's! They're even faster, and ?cheaper? maybe as well.
  • 0 Hide
    Turas , August 26, 2008 5:19 PM
    nbk_redspyI agree, I expected to see the SSD numbers as well, but from the last couple of SSD articles, Tom's seemed to be a little behind on the latest SSD models. For example, using the OCZ Core when the superior Core II was commercially available.

    AS far as I know the Core II are not yet available.
  • 0 Hide
    yyrkoon , August 26, 2008 6:52 PM
    Well, you can get the Seagate ST3146356SS (147GB) version for around $285 usd before shipping. You can also buy a decent non RAID/PCIe controller(2 port as I recall) for around $80 usd. With shipping and all factored in, we're talking about roughly $400 usd for a single 147GB drive + controller.

    That is not too bad *if* you need to performance for video editing, or possibly image retouching(scratch disk) if you are a professional. You may even see a noticeable performance increase on a gaming rig, but really the cost/storage ratio really does not make sense for most. Also while you may have mentioned it, I did not see mention of it - SSDs having no moving parts, would not cause issues with performance because of vibration. Another thing is that *if* you stripe, access times may still nearly double(as compared to a single drive), but access times on SSDs being as small as they are . . . well, it would become a moot point.

    On the other hand, I have been thinking for a long time now that SAS HBA's in the home could make sense for the enthusiast. SAS HBA + decent SATA drives may not offer the same performance, but with the right card, and possibly SAS expanders, SAS + SATA == a solution that can scale over time, and can possibly offer performance greater than the home desktop could ever hope to keep up with. Cost effective SAS expanders however are hard to find(for said purpose), which could be the only caveat, other than having an external(*if* external) array that can not be hooked up to just any old system.

    Good to see that Seagate is still pushing that performance level higher with their Enterprise drives.
  • 2 Hide
    yyrkoon , August 26, 2008 7:05 PM
    somasaintneiroatopelcc, sorry.. SAS requires an aggressive commitment. typically SAScontrollers cards come in pci-x, but the dell perc 5i line canbe found [ebay] in the pci-e version.. given your mainboard hasa free pci-e 8x slot .. which usually means an SLI board.. or triplefor those of you already running twin rigs. the benefits here beingyou can set your stripe size to 1mb.. and you get ddr256mb cache + BBU.here are my figures: via HDTach [raid-0: 73GB 15k sas fujitus + perc5i]http://img403.imageshack.us/img403/940/boredeq1.jpg


    Dell is not the only company you can buy SAS HBAs from. Adaptec, LSI Logic, and 3Ware all sell SAS HBAs. As does Areca, and several others I do not care to think of at the moment. You can get them at anywhere from $80usd for a basic controller, on up into $1000's in the PCIe variants. PCI-X variants are mostly a bit cheaper than their PCIe counterparts, but that probably has to do with supply, and demand.

    The price point for a decent controller with 128 + device support through expanders starts at around $400-$450 usd. Expanders on the other hand will also set you back $300-$400 depending on where you get it from, and in what form. Expander racks are ridiculously priced . . .
  • 0 Hide
    kittle , August 26, 2008 10:20 PM
    Yes SAS is expensive - but you get what you pay for, namely high performance, and reliability. In the server market, when your data is worth large sums of money or downtime is expensive, then the higher price of these drives make perfect sense.

    The other thing that wasnt mentioned is heat. the 15krpm spindle speed produces quite a bit of heat, so the drive must be cooled, which means fans and still more noise, and so forth and so on...
  • -1 Hide
    nvalhalla , August 27, 2008 2:14 PM
    MathosYes instead of MTBF you have time before cells start dieing out from too many read write cycles.



    When HDD fail it's all at once. I'll take slow cell death over catastrophic failure any day.
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