Divan Santana wrote:
Greetings :)
I have a openbsd 76 system (dmesg [1]) with bioctl raid5 setup. It
achieves performance writes of between 18-43 MB/s with a dd test[2] and
7-11 MB/s with rsync tests[3]. But the backend drives are reported to
write at 220MB/s according to it's vendor spec [4]. I would expect with
a raid5 setup, that the write speed would increase slightly then a
straight drive. But the performance is very slow (7-11 MB/s with
rsync). Is this normal experience in OpenBSD? Perhaps it's slow for
some reason I don't understand, like perhaps it's doing a random write,
but why would it do that? The disk random 4K write speed is reported to
be a terrible 0.79 MB/s according to userbenchmark.com [5] while
sequential write is 142MB/s.
Is there anything I can do, to try improve the performance? I haven't
find a document or article that discusses how to troubleshoot this
further.
As far as I understand, raid 5 performance is usually slower than you
would expect because parity data needs to be computed and written to the
drives too.
