IBM serveraid and linux

[Andrew Hammond]

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Jason Shein wrote:
| Does anyone on this list have any experience with IBM serveraid?
|
| I have 2 identical Netfinity 5600's setup with RAID 5 across 5 18gb
drives, 3
| live, 2 hot spares. I am constantly having drives go DDD ( amber light ).

Why on earth would you configure your disk that way?! If you've got 5
18G disks and need 36G storage, then it's a no brainer: RAID 10 + 1
hotspare. Don't use the RAID card for anything but JBOD. Aside from the
performance sucking, it creates a huge SPOF. The only thing of any real
value on a hardware RAID card is battery backed write cache. If
possible, get a split backplane and put the two halves of the mirror on
different SCSI channels, preferably on different SCSI cards.

With the advent of reliable software RAID, I have never seen an
application in which a RAID card was a good idea. You can _always_ do
RAID 10 faster and safer in the kernel. If you really need high
performance or high availabliltiy, then look at a SAN / disk array
solution. Otherwise, dozens of 10kRPM SATA disks hung off an inexpensive
3ware or highpoint controller doing JBOD is obviously the way to go.

Before some idiot suggests using RAID3/4/5 to get more storage out of
your disk, I should point out that they are over complicated, processor
intensive solutions to a problem that doesn't exist anymore. You'd think
they would just go away in this age of super cheap disk. It is pretty
stupid to believe that it is more economic to waste hours of sysadmin
time, degrade performance and risk data to save a couple of thousand
bucks on disk.

- --
Andrew Hammond    416-673-4138    ahammond-swQf4SbcV9C7WVzo/KQ3Mw at public.gmane.org
Database Administrator, Afilias Canada Corp.
CB83 2838 4B67 D40F D086 3568 81FC E7E5 27AF 4A9A
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