craig@ctrust.com wrote:
>What kind of controller is on the intel boards? I have a number of
>VIA controlled boxen in the field that are using high point controllers.
>They don't seem to have any problem dealing with RAID. Linux
>doesn't even know it is there (as it should be) The disks register
>either as SCSI disks or an ATARAID disk (depending on kernel
>version). You may consider a PCI IDE raid controller if these boxen
>are very important. Adaptec makes a very nice one, I'm pretty sure it
>is a 1200 or something like that. There may be a newer unit out
>there that will deal with ATA133, but be careful to make sure it has
>linux support.
>
>
Hardware raid is great, though IDE RAID has its own problems at times.
If you use 3ware controllers, for example, expect speed issues. Also,
IDE drives have a great infant mortality rate and seem to be failing
more and more as the density goes up, regardless of manufacturer. I will
not make any blanket suggestions for IDE RAID for this very reason.
That's not to say that I would spend the money on SCSI hardware, merely
that IDE RAID is a pain to get right, particularly for a farm of servers.
>Servers should NEVER have a software RAID for the very reason
>you are having trouble.
>
>
Oh, we have had quite a bit of trouble with software RAID and IDE disks,
particularly in a RAID 0 or RAID 5 configuration. Simply put, IDE drives
throw errors when they are relocating bad sectors, which tends to throw
Linux software RAID into a tizzy. We have had great luck with software
RAID 1, which is the *only* Linux software RAID we will use on any of
our boxes.
You may not notice this when you're running one or two boxes, but when
you're running hundreds of the things, statistically it becomes very
painful.
As to swapping to a software RAID 1 mirror: sure, it's possible - though
not recommended. If your application is really that critical, consider
architecting it to span a number of boxes in a cluster with a load
balancer or heartbeat failover - hardware eventually breaks, regardless
of manufacturer. If you can't change your application, consider paying a
small fortune for a higher end server from HP or Dell, and cross your
fingers.
- Ian
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