Re: [SLE] Which motherboard/RAID controller for home file-server?

From: Louis Richards (louis_at_ldrinteractive.com)
Date: 08/03/04

  • Next message: Jorge Fábregas: "Re: [SLE] Fedora vs SuSE sysctl question" 
    Date: Mon, 02 Aug 2004 21:56:58 -0400
To: suse-linux-e@suse.com

    Niclas Arndt wrote:

    > Highpoint claims to have RAID support for their RocketRAID 1542 and
    > 1544 for kernels 2.4 AND 2.6. Has anybody tested it under SuSE 9.1?
    >
    > I know that it is probably not pure hardware RAID, but you still get
    > some benefits over Linux Software RAID:
    >
    > When the primary drive fails, you won't have to boot with the rescue
    > CD and rewrite lilo to the mirrored drive so that you (hopefully) will
    > be able to boot from it without moving it to the IDE primary.

    There is absolutely no reason for this with the built in software RAID
    either, although it gets said a lot. I have grub loaded to both MBRs and
    can boot from either drive at any time regardless of which drive fails.
    The built in md drivers have been noticeably faster for me in Fedora and
    SUSE (9.0). I haven't bothered with any other software solutions in 9.1.

    As another poster said, if you need heavy duty throughput, go with a
    real hardware solution. But ... I have been pleasantly surprised by the
    performance of the md drivers.

    > You ususally get SDx devices instead of HDx, which differentiates your
    > hard drives from your CD / DVD drives. This might be nice if your
    > motherboard manufacturer decided to put the integrated IDE in the last
    > PCI "slot". At least that's the case with my mobo. Adding another IDE
    > controller totally screws up the current device order. :-(
    >
    > If you have used your drives before you use them for software RAID you
    > may end up with lots of strange error / warning messages. It is
    > supposedly possible to "clean" a drive, but could anybody tell me how?
    > I have roamed cyber space to no avail in the quest for enlightenment.
    > Maybe also explain what all the boot log probing messages actually
    > mean, i.e. do I have to worry about any particular messages? Maybe a
    > slightly less verbose probing would be good to keep users from
    > needless worrying ?

    dd if=/dev/zero of=/dev/hdb
    The above command should wipe a drive for you. Just change hdb to the
    drive needing an attitude adjustment.

    > One strong benefit with software RAID is that you can rebuild the RAID
    > array in production use, while the "hardware" RAID cards may have to
    > rebuild the mirror in its BIOS before booting. It takes hours
    > rebuilding a 160 GB drive, I noticed with my Promise FastTrak 133 lite...

    A good hardware RAID controller will allow you to hot swap a running
    system. No commands to type at all. Just pull out the bad drive and put
    in a new one. With software RAID you generally have to shut the system
    down, replace the drive, reboot, fdisk the drive, and raidhotadd the
    partitions into the array.

    > Concerning drive interface, I definitely recommend sata, partly
    > because they are generally (always?) presented as SDx devices.
    >
    > Performance-wise software mirroring is quite comparable to hardware
    > mirroring. You only really benefit from hardware RAID when doing
    > write-intensive, small-IO RAID 5. This will also require a large RAID
    > controller with a battery-backed cache.
    >
    > One final piece of advice: Don't neglect your boot and swap drives.
    > All drives should be protected by RAID. If you have lots of data,
    > consider RAID 1 for /, swap, boot, and RAID 5 for your data.
    >
    I couldn't agree more. Mirroring boot and swap just makes sense.

    Louis 

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