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To RAID Or NOT To RAID?

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  • To RAID Or NOT To RAID?

    Hi,

    I'm considering whether to flash out for 2 more drives and an Adaptec 2410SA SATA RAID card, a 3 x 1TB array, RAID 5 so 2TB capacity in all. Space isn't the issue (TBH it really isn't worth going for much less than 1TB drives as the price difference between them and most of the lower capacity ones is negligible), my primary reason for going in this direction is speed.

    However the only ESXi 4.0 compatible RAID adapter I can afford (on eBay) is the Adaptec 2410SA which is SATA 1 (150GB transfer rate) where both the drives and onboard SATA are SATA II (300Gbs transfer in principle). The onboard SATA is RAID capable but the DELL Precision 490 RAID isn't recognised by ESX 4 apparently (also no cache and probably uses up CPU slice rather than a proper RAID card with it's own onboard processing) so I can't use that for ESXi.

    I could go for 4 x 500Gb drives RAID 5 but that would be more expensive (200 as opposed to 120 for the same amount of space given I already have one of the 1TB units), the drives typically have only 16MB cache (as opposed to 32Mb on the 1TB drives) and, as I say above, I already have 1 of the 1TB drives (Samsung F2 EcoGreen).

    So my question is RAID running across a SATA I controller or non-RAID running natively on the 490's SATA II ports?

    Kyu
    J C Rocks (An Aspiring Author's Journey)
    The Abyssal Void War: Stars, Hide Your Fires

  • #2
    Re: To RAID Or NOT To RAID?

    I'll bring up one point first.

    Is having 1 parity drive useful to you compared to none? Maybe its not an important feature for you, but pointing it out.

    Most SATA 7200RPM drives have performance of 50-100MB/s which is not maxing the bandwidth SATAII can handle. Plus the fact that over time 1 drive will not sustain performance as well as a RAID config due to data fragmentation. If parity wasn't important then you could have comparable performance with 1 drive using SSD.

    Really it boils down to how much you want to spend. And how important are the VMs you're running.

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    • #3
      Re: To RAID Or NOT To RAID?

      and I will add to that as well what kind of environment and workloads you are running and what kind of performance you would like to get from the VM's?
      Maish
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      • #4
        Re: To RAID Or NOT To RAID?

        Originally posted by eddo View Post
        Is having 1 parity drive useful to you compared to none? Maybe its not an important feature for you, but pointing it out.
        Form the POV of redundancy? It's *ONLY* a home server but it will host data that's important to me and my family so I'm happy to buy the extra drive I need to give redundancy ... it won't be hotswap but it should at least keep us up and running.

        Originally posted by eddo View Post
        Most SATA 7200RPM drives have performance of 50-100MB/s which is not maxing the bandwidth SATAII can handle. Plus the fact that over time 1 drive will not sustain performance as well as a RAID config due to data fragmentation. If parity wasn't important then you could have comparable performance with 1 drive using SSD.
        So using RAID will likely be better than a single SATA II because A typical drive doesn't even reach SATA I max bandwidth?

        Originally posted by eddo View Post
        Really it boils down to how much you want to spend. And how important are the VMs you're running.
        Some of the VM's will be test but a couple of them will be important.

        Originally posted by Maish View Post
        and I will add to that as well what kind of environment and workloads you are running and what kind of performance you would like to get from the VM's?
        Home so not important in a business/money sense but still important to us as a family.

        I'm now thinking of buying 4 x 640GB drives which will cost about 180 (212 if I go for 32Mb cache drives) and that would allow me to configure an array of just under 2TB with 1 redundant drive.

        Thanks for the replies

        Kyu
        J C Rocks (An Aspiring Author's Journey)
        The Abyssal Void War: Stars, Hide Your Fires

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        • #5
          Re: To RAID Or NOT To RAID?

          Go RAID for data resiliance and the more drives you use the more performance you will gain

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