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Date: Thu, 17 Mar 2016 16:45:10 -0400
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 <CAK17Jmku_RsBRHYKEVbT5KY9Cg1O4J6Zgpk4zYTXq2UQ1=LeMA@mail.gmail.com>
Subject: Disk Benchmarking Question
From: Dave Stibrany <dstibrany@gmail.com>
To: pgsql-performance@postgresql.org
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I'm pretty new to benchmarking hard disks and I'm looking for some advice
on interpreting the results of some basic tests.

The server is:
- Dell PowerEdge R430
- 1 x Intel Xeon E5-2620 2.4GHz
- 32 GB RAM
- 4 x 600GB 10k SAS Seagate ST600MM0088 in RAID 10
- PERC H730P Raid Controller with 2GB cache in write back mode.

The OS is Ubuntu 14.04, I'm using LVM and I have an ext4 volume for /, and
an xfs volume for PGDATA.

I ran some dd and bonnie++ tests and I'm a bit confused by the numbers. I
ran 'bonnie++ -n0 -f' on the root volume.

Here's a link to the bonnie test results
https://www.dropbox.com/s/pwe2g5ht9fpjl2j/bonnie.today.html?dl=0

The vendor stats say sustained throughput of 215 to 108 MBps, so I guess
I'd expect around 400-800 MBps read and 200-400 MBps write. In any case,
I'm pretty confused as to why the read and write sequential speeds are
almost identical. Does this look wrong?

Thanks,

Dave

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<div dir=3D"ltr"><div>I&#39;m pretty new to benchmarking hard disks and I&#=
39;m looking for some advice on interpreting the results of some basic test=
s.<br></div><div><br></div><div>The server is:</div><div>- Dell PowerEdge R=
430</div><div>- 1 x Intel Xeon E5-2620 2.4GHz</div><div>- 32 GB RAM</div><d=
iv>- 4 x 600GB 10k SAS Seagate ST600MM0088 in RAID 10</div><div>- PERC H730=
P Raid Controller with 2GB cache in write back mode.</div><div><br></div><d=
iv>The OS is Ubuntu 14.04, I&#39;m using LVM and I have an ext4 volume for =
/, and an xfs volume for PGDATA.</div><div><br></div><div>I ran some dd and=
 bonnie++ tests and I&#39;m a bit confused by the numbers. I ran &#39;bonni=
e++ -n0 -f&#39; on the root volume.</div><div><br></div><div>Here&#39;s a l=
ink to the bonnie test results</div><div><a href=3D"https://www.dropbox.com=
/s/pwe2g5ht9fpjl2j/bonnie.today.html?dl=3D0">https://www.dropbox.com/s/pwe2=
g5ht9fpjl2j/bonnie.today.html?dl=3D0</a></div><div><br></div><div>The vendo=
r stats say sustained throughput of 215 to 108 MBps, so I guess I&#39;d exp=
ect around 400-800 MBps read and 200-400 MBps write. In any case, I&#39;m p=
retty confused as to why the read and write sequential speeds are almost id=
entical. Does this look wrong?</div><div><br></div><div>Thanks,</div><div><=
br></div><div>Dave</div><div><br></div><div><br></div><div><br></div>
</div>

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