Re: Performence test on ceph v0.23 + EXT4 and Btrfs

[Jeff Wu <cpwu@tnsoft.com.cn>]

在 2010-12-01三的 01:07 +0800，Gregory Farnum写道：
> On Mon, Nov 29, 2010 at 10:19 PM, Jeff Wu <cpwu@tnsoft.com.cn> wrote:
> > Is "40-50MB/s" the speed that it run bench at local btrfs disk ?
> > not the speed that run bench from client to osd server ?
> > with this speed ,run bench from client to osd server ,will which  get
> > about 20~25MB/s( 40~50MB /2 )speed ?
> Data on Ceph is replicated across 2 OSDs (by default; this is
> configurable). So while figuring out potential performance involves a
> lot of variables, in a simple case like this where you aren't bounded
> by network bandwidth you'll find that your read/write performance
> simply tracks the slower disk. I'd expect your Ceph tests (at least
> the streaming ones) to run at 40-50MB/s.

Hi Greg,thank you very much for your quickly reply.
> 
> Given that everything else is okay, I cannot stress enough that
> running without a journal is going to cause significant performance
> degradations. I have a hard time believing that it's responsible for
> 13-second latencies, but it's possible. So how about you set up a
> journal (it can just be a file or new partition on the drives you're
> already using) and report back your results after you do that. :)

I will add journal to ceph.conf to try it . 



> Adding a journal to the OSDs lets them turn all their random writes
> into streaming ones.
> -Greg

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