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RAID Performance Comparison

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  • RAID Performance Comparison

    Here's one for you hardware bofs.

    1) 146GB 3.5" 15K RPM SAS x 2 in a RAID-1


    2) 146GB 2.5" 10K RPM SAS x 4 in a RAID-1+0

    Which has better performance for reads and writes across the entire capacity fo the RAID?

  • #2
    Re: RAID Performance Comparison

    This is certainly a good question.

    Having looked in to using SAS drives myself, I know that 2.5" compared to a 3.5" SAS drive of same speed, means that the 2.5" SAS has slower Transfer Speed but quicker access time. 2.5" drives also consume less power and are useful for creating additional space on a storage unit.

    IN your scenario, as the 2.5" drive is slower that the 3.5" drive and the transfer speed is slower anyway, I would think Option 1 is best. When saving data to Option 2 (Striping and mirroring), I feel there will be a performance issue with Transfer Speed effecting the striping when writing.

    This is just my opinion though. You will certainly get acceptable performance from Option 1. I have 1 server using Raid 1 with SCSI drives an don't have any problems.

    What kind of data or applications or server will be installed on the drives?


    • #3
      Re: RAID Performance Comparison

      I'm intending to install some Exchange 2007 roles onto servers, and believe that storage performance is going to be the bottle neck, considering I'm using quad Xeon's and 8GB+ of memory.

      In the past I've used RAID-1 for servers that don't require large amounts of storage, and RAID-5 for those that do.

      The fact that in a RAID-10 configuration, 2 drives can fail (so long as they don't belong to the same mirror) without operational loss is attractive, considering the importance of email.

      My current spec has 2U servers with 4 x 146GB 3.5" SAS drives in RAID-10, but I can squeeze in 4 x 2.5" drives into a 1U server, and rack-space is at a premium.

      The downside is that 2.5" 10K drives are damn expensive, and I wouldn't have space for hot spares, so would need to keep cold ones instead.


      • #4
        Re: RAID Performance Comparison

        Ok, I see. You mentioned Raid 1 + 0 below and just realised it another name for Raid 10. For optimal peformance, you could setup Exchange 2007 with Raid 1 for OS, Raid 5 or 10 for the database and another Raid 1 for log files, but as you mention, you don't have that luxury.

        Raid 10 is a set of mirrored drives effectively mirroring each other. I would say that you should only allow for 1 disk failure. Write speed is quicker on this one. You mention this below anyway.

        To allow two disk falures, you need Raid 6.

        However, it sounds as if Raid 10 will be best for you in this case seeing that you will have a hot swap drive to hand.


        • #5
          Re: RAID Performance Comparison

          I'm only looking at this storage configuration for the ET and CAS/HT roles. The mailbox servers are clustered with a SAN so they are fixed at 2U.

          Basically, can I use 1U servers for the other roles without seriously impacting performance?

          Of course, this may impact any other servers I setup in the future.


          • #6
            Re: RAID Performance Comparison

            You should be fine. At the end of the day, a 10,000 rpm SAS drive is still faster than a considerable number of hard disk drives in servers today, at base level anyway.

            1U will give you the extra rack space as well, if you need that.


            • #7
              Re: RAID Performance Comparison

              I don't really know what equipment you're using at the moment, but in an HP DL360G5 (Intel processor) or DL360G5 (AMD processor) you can have as much as 6 SAS disks for 1U of rack space.
              In the past, you could have add to it StorageWorks 50 Modular Smart Array, taht gave you another 10xSAS disks in 1U. That means 16 SAS disks in 2U... Unfortunately, MSA50 is no longer available

              Sorin Solomon

              In order to succeed, your desire for success should be greater than your fear of failure.