Re: Infiniband 40GB

[Mark Nelson <mark.nelson@inktank.com>]

On 6/4/12 6:40 AM, Alexandre DERUMIER wrote:
> Hi,
>
> I'm currently doing some tests with xfs, debian wheezy with standard libc6 (2.11.3-3) and 3.2 kernel.
>
> I'm doing some iostats(3 nodes with 5 osd), and I see constant writes to disks.(as the datas are flushed each second from journal to disk).
>
> Journal is big enough (20GB tmpfs) to handle 30s of write.
>
> Do you think it's related to the missing syncfs() support ?
>
> -Alexandre

Hi Alexandre,

I've included some seekwatcher results for rados bench tests using 16 
concurrent 4MB writes on XFS OSD.  One shows ubuntu oneiric and the 
other precise (ie no syncfs support vs syncfs support in libc). 
Unfortunately the original test was on 0.46 and the second test was on 
0.47.2, so multiple things changed between the tests.  Both were tested 
with kernel 3.4.  Interestingly the seeks/second don't seem to drop much 
but the overall performance has about doubled.  This was using a single 
7200rpm disk for the OSD data disk and a seperate 7200rpm disk for the 
journal in both cases.  I'd definitely try 0.47.2 with a new libc though 
and see how that works for you.

ceph 0.46/oneiric:
http://nhm.ceph.com/movies/mailinglist-tests/xfs-osd0-oneiric-3.4.mpg

ceph 0.47.2/precise:
http://nhm.ceph.com/movies/mailinglist-tests/xfs-osd0-precise-3.4.mpg

Mark