Optimal stripe size obviously depends on the circumstances.
On one RAIDed server we saw improvements when we switched from 32KB chunks
to 1MB chunks, and then again when we switched to 16MB chunks (yes,
chunk-size 16384K). The application is a Diablo news relay server with
three 4GB spindles under RAID0 handling news (and one non-RAID spindle for
booting the O/S). The larger chunk size appears to decrease the likelihood
of backlogged outbound queues interfering with real-time traffic.
We had started with smaller chunk sizes so that large file I/O could be
spread across multiple spindles but this was only efficient when all peers
could keep up. Once a peer starts to backlog, the seeks between the
real-time hot-spot and the backlogged data overwhelmed all other factors.
For those designing news relays, be advised that the server mentioned above
is effectively obsolete and will be replaced as soon as RAM prices drop
back to reasonable levels.
--Mike
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Mike Bird Tel: 209-742-5000 FAX: 209-966-3117
President POP: 209-742-5156 PGR: 209-742-9979
Iron Mtn Systems http://member.yosemite.net/
