On 13/10/14, 20:59, Keith Keller wrote: > On 2014-10-14, Joakim Ziegler <joakim at terminalmx.com> 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 at terminalmx.com - 044 55 2971 8514 - 5264 0864