Michael Cunningham wrote:
> Timing buffered disk reads: 32 MB in 1.87 seconds =17.11 MB/sec
>
> I can understand the write performance but I would think the read
> performance would be better given that it should be reading from both
> halves of the mirror?
What is your chunk size set at in the raidtab file? In my testing, I've
found that lower chunk sizes usually boost performance on these benchmarks,
though possibly not in the real world. A chunk size of 4 (4k) seems to be
ideal for these benchmarks and for fast sequential reads, but might
adversely affect your seeks/min or throughput on a heavily accessed file
system.
this isn't to say that there aren't room for improvements in software raid
performance, as even with a 4k chunksize performance will level off after
four drives, eventually dropping lower. But with two drives and a low
chunksize you should be able to see greater than a single drive's speed,
though not 2x.
tom
