Implement RAID with Fedora 10

grub87grub87
edited July 2009 in Hardware
Hi!! I'm going to implement a RAID 0 (i chose this level of RAID because i will use the server for rendering, is this the best choice for rendering??) on a DELL PowerEdge T605 which has 4 spaces for HDs, it has already two 250GB 7200rpm SATA disks and i'm going to buy another 2 HDs. My question is, which characteristics must these new HDs could have? I mean the maximum supportable characteristics in capacity, speed, etc for implementing the RAID.

Also i have another server with the same characteristics but this one i'm intending to use it for storage only, i guess this should have a RAID 1, correct me if i'm wrong, and also i would like to ask you the same question as with the other server about the characteristics of the new HDs.

Another question i have is: do i need a driver for this implementation??

By the way we will install Fedora 10 in both machines, they each have 2 AMD Quadcores. Thanks for your help!!

Comments

  • ardichokeardichoke Icrontian
    edited July 2009
    There is no max or min drive specs necessary for RAID. That's kind of the point of RAID. You can use any disks for it. That said, obviously the faster the disks the faster the array will be. Also keep in mind that in most RAID arrays your disks are clipped to the size of the smallest disk (realistically, you want to use identical disks if possible).

    RAID 0 is good for speed but remember that if any one disk in the array fails your data is gone so backup often. RAID 1 is good for redundancy but you are limited to the size of one disk. You should still backup often though. If you have 4 disks, I would recommend going with either RAID 5 or maybe RAID 1+0 for the storage server, you'll get more usable space that way.

    As for the drivers, that all depends on if you are using a hardware RAID controller. It looks like the default RAID controller in the PowerEdge T605s are software RAID cards. That makes them pretty much useless. You'll have to set up your array through LVM most likely. A better choice would be to buy an actual hardware RAID controller which has drivers built into the kernel. Then you just set up the array in the cards BIOS and it would show up as a single drive to the OS.
  • lordbeanlordbean Ontario, Canada
    edited July 2009
    ^

    As he says, a hardware RAID card would be a very wise investment for this sort of application. You could do 4-disk RAID0, but that means if any one of the 4 drives fails, the data's gone. Assuming a hardware RAID card, my choice would probably be 4-disk RAID5 with this setup... with 4 250GB hard drives, a RAID5 array would give you 750GB (1000-250 for the parity disk), and fairly good read/write speeds. As I understand it though, you basically need a hardware raid controller to do this, because implementing software RAID5 is very demanding on the CPU, which is not what you want in a video rendering system. It would bottleneck the rendering speed.
  • grub87grub87
    edited July 2009
    Hi again! thanks for your advice. I checked my server and internally has the cables for 2 more HDDs and has the SAS6 /iR Adapter RAID Controller, so i guess there is no need for an extra controller because the OS recognize this controller. One thing that i forgot to ask is that if the extra HDDs that i'm buying SHOULD have the same speed as the others, 7200 or i can combine 10,000 rpm and 7,200.
    I read that while i'm installing Fedora 10 there is an option to configure the RAID or how do i configure it??? And also the level of RAID? This time will be RAID 0 and RAID 5 or 10 as you told me.
    Thanks!!
  • ardichokeardichoke Icrontian
    edited July 2009
    Yes, you can mix different speed drives as long as you aren't using one of the RAID levels that require synchronized spindels. The only levels that do are not widely used (3 and 4 I think). Just keep in mind that with RAID you are always going to be limited by the lowest spec hardware so there's really no point in buying 10000 RPM drives if the ones already installed are 7200... you won't get any performance increase out of it and may actually see a decrease.

    As for that RAID card, it's a software RAID card and I would highly suggest chucking it and getting a hardware RAID card. Especially if you want to do RAID 5. Software RAID 5 is bad for system performance (believe me, I used to run a system with software RAID 5). If you really want to stick with software RAID, go RAID 10. As for setting it up, I'm not sure how specifically in Fedora as I use Debian/Ubuntu usually... It will need to be configured during install at the partitioning section. Choose manual partitioning. The Fedora documentation here can probably explain it better than I can.
  • jonfleck88jonfleck88 Columbia, PA
    edited July 2009
    grub87 wrote:
    I read that while i'm installing Fedora 10 there is an option to configure the RAID or how do i configure it??? And also the level of RAID? This time will be RAID 0 and RAID 5 or 10 as you told me.

    Here's a pretty good tutorial on howto setup raid in Fedora 11 Installing Fedora 11 and Setting up a RAID 0, 1, 5, 6 or 10 array. I would think that it's pretty similar to setting it up on Fedora 10. BTW, this is a software RAID setup, but from comments that I've read if you're setting up a software RAID 10 and have a powerful machine (like your AMD quad core) the performance should be very good.
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