On 13/10/14, 20:59, Keith Keller wrote:
On 2014-10-14, Joakim Ziegler <joakim@xxxxxxxxxxxxxx> wrote:
So, if I use iozone -a to test write speeds on the raw device, I get results in
the 500-800MB/sec range, depending on write sizes, which is about what I'd expect.
However, when I have an ext4 filesystem on this device, mounted with noatime and
data=writeback, (the filesystem is completely empty) and I test with dd, the
results are less encouraging:
My first question would be, why not test the filesystem with iozone too?
(And/or, test the device with dd.) You may or may not come up with the
same results, but at least someone can't come back and blame your
testing methodology for the odd results.
(Just as an aside, if your 6.4 box is on a public network, you should
probably consider updating it as well, since many security and bug fixes
have been issued since 6.4 was released.)
If you are still getting poor results from ext4, you have at least two
more options.
==Check with the ext4 mailing list; they're usually pretty helpful.
==Try your tests against xfs. Try to make sure your tests are
replicating your use cases as closely as you can manage; you wouldn't
want to pick a filesystem based on a test that doesn't actually
replicate how you're going to use the fs.
Googling shows some people who solved what seems like a similar problem with a
kernel upgrade, so I'm going to try that. This box is on 2.6.32-358, and
2.6.32-431.29.2 seems to be the newest. At least it's a factor to eliminate.
--
Joakim Ziegler - Supervisor de postproducción - Terminal
joakim@xxxxxxxxxxxxxx - 044 55 2971 8514 - 5264 0864
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