Re: [SLUG] Is RAID worth doing?

From: Ian C. Blenke (ian@blenke.com)
Date: Thu Jul 13 2006 - 14:07:24 EDT


steve szmidt wrote:

>On Thursday 13 July 2006 13:14, Ian C. Blenke wrote:
>
>
>H/W RAID has always been my preference (except for some smaller places) with
>next to no fuss. For years I've now relied on 3Ware and had very good
>statistics. S/W RAID is pretty interesting and obviously cheaper. On heavy
>load it does have a problem keeping up with writes and of course you cannot
>do hot swap last time I checked.
>
>

Our experience with 3Ware has been that failures often go unseen, write
speed suffers drastically, and adding/removing drives requires extra
intervention.

In the NKS farm, we simply pop in a blank drive and restore the
partitioning:

    sfdisk -d /dev/hda | sfdisk -f /dev/hdc

Then reboot. Viola, the system comes back up and starts resyncing.

If a drive is hot swapped, even a boot can be avoided. Just re-read the
partitioning and mdadd back the new partitions (partprobe is from the
parted package, you just need something that can do a BLKRRPART ioctl()):

    partprobe /dev/hdc
    mdadm --manage /dev/md0 --add /dev/hdc1
    ...

and so on.

 - Ian C. Blenke <ian@blenke.com> http://ian.blenke.com
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