Pat Regan on 6 Sep 2004 19:02:04 -0000

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Re: [PLUG] Disaster Recovery Strategies

On Thu, 2 Sep 2004, Eric Hidle wrote:

> What you really want is a Raid-5 controller with a hotswap chassis for your
> drives. 3Ware makes excellent hardware with linux source drivers as well.
> It's expensive, but if you want true single-drive-failure-zero-downtime
> operation, it's the way to go, IMHO. Raid5 has saved my butt on more than
> one occasion.
> E

3ware makes excellent hardware, but it is absolutely dog slow doing writes
on raid 5 (as if I thought it could get any worse :p).  IDE drives are
cheap enough to do raid 10.

When I originally got my 8 port 7800 card, I was doing Raid 0 across four
40 gig drives.  When the drives started to show their age, and I had to
RMA one of the drives, I temporarily switched to raid 5 on the other 3
drives.  Once the OS cache got filled up on a "big" file copy, the machine
became VERY unresponsive.

The cards don't have enough cache for raid 5.  I've heard the newer,
higher end cards have an actual cache now though.  So it may work out well
with a new card.

If I were doing IDE raid for the primary disk in a desktop (regardless of
raid controller) I would use raid 1 or 10.  I would probably save raid 5
for storage that doesn't need to be fast, or receives mostly reads.


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