Hello there, I have a server in our test lab (specs below) that
doesn't appear to be getting nearly the write speeds that I was
expecting (test details below). In "top" terminology, there is one
CPU core at about 30% SI and each core shows anywhere from 1 to 15 %
SY and about the same for WA.
My main question: what tools do I need to get some visibility as to
what is going on within the megaraid_sas module and on the SAS
controller itself? I have gone about as far as I can go with
utilities such as top and MegaCli.
For simplicity, I am only focusing on raw write speed straight to the
block device. I have a few benchmarks I use, mainly Orion and some of
the Phoronix suite, but Currently the easiest test is just:
dd if=/dev/zero of=/dev/sdc ibs=1048576 obs=1048576
The main symptom is that with a single disk I can push > 300MB/sec,
and with a pair in RAID0 I can get over 600MB/sec, but with 5 of these
in RAID0 it never goes above around 700MB/sec. My next test will be
to use each disk as a separate device and try software raid (or just
writing to each disk simultaneously).
Thanks,
Mark
p.s. system specs:
Dell 720xd, H710 ("mini") controller
5x Micron P300 SATA SLC SSD's
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