I'm trying to figure out a good set-up for a Linux machine (Netfinity
7000M10 or 8500M10, still deciding) for optimal sequential-block-write
performance (block size can be changed arbitrarily).
The machine will be hosting 240 SCSI drives (36.4GB each) (plus 1
or 2 to boot from). The drives will be encased in 24 Timpani drive
enclosures. (each Timpani can go to a single SCSI channel and with a
3-channel card (like an IBM ServeRAID), 30 drives can be off one card).
My current thought is to take each of 8 card's and put 15 drives each
into RAID0's done in hardware (therefore 16 hardware raid's). Then for
protection (need to be able recover from single-drive failures), do a
s/w RAID5 across the 16 h/w raid's so we can do the XOR's with the 4 or
8 KNI-enabled Xeon's (although there may be memory bandwidth issues here).
Unfortunately, I'll need something that is capable of good throughput
with RAID0 in hardware over 15 drives. The IBM ServeRAID controllers
can't deal with more than 8 drives for a 64k stripe size, and
lowering the stripe size has a large (2.5x-3x) performance hit for the
sequential-block-write case that I'm looking for. High performance
Linux-friendly RAID controllers that can deal with 64k (or larger?)
stripe sizes and 15 drives (in at least two RAID0's) would be good to
know about.
The box has nothing else to do, I simply need 240 drives in some
configuration that gives me protection from single-drive failures (or
in this case, single failure of a 15-drive RAID0 drive group)
The "kicker" is that something along the lines of LFS (which with the
latest s/w raid patches for 2.2.10, finally coexists at least somewhat
happily) will be needed since the files to be stored will be along the
lines of 8GB to 32GB in size (each). "smugfs" seems like it might be a
more appropriate since the smallest file to be stored here will be 8GB
and hence I don't care about any efficency in storing smaller files,
but it appears unmaintained.
For various reasons (long story), NT (and other OS's) is to be avoided
if at all possible, so I'm hoping there's a Linux possibility.
Thanks for any help, advice, and suggestions,
James Manning
PS cc: me if at all possible... vger doesn't seem to like my subscribe
attempts :(
--
Miscellaneous Engineer --- IBM Netfinity Performance Development
