Quoting "Bryan J. Smith" <thebs413@xxxxxxxxxxxxx>:
> He still should be seeing at least 100MBps for RAID-5 writes
> on a 3Ware Escalade 9500S with 6-discs (180MBps is about the
> maximum for RAID-5 writes on the 9500S' ASIC with DRAM). The
> ASIC is fairly good at sequential writes to RAID-5, and there
> is enough DRAM to buffer all but the heaviest of random I/O.
What I found with an old(er) 3ware 7500-8 (does not use same device driver as
9xxx cards) in RAID5 configuration was that it makes big difference using ext2
or ext3 (doubles the write speed, no effect on read speed). With ext3 I used
internal journal (external migh have helped, but haven't tested it). Changing
journaling options and/or journal size had almost no effect. Anyhow,
journaling (using default options, internal journal) should not have that high
impact on write speed (not even close).
The card was considerably faster with 2.4 kernel than with 2.6 kernel
(tests run
on same hardware, same configuration, ext3 file system). About 20% faster
writes and 40% faster reads.
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