Slow performance

[Eric Sandeen]

Steven Adams wrote:
> Hi All,
> 
> I am using XFS for the first time of one of my servers. I was using 
> rsync to copy the files from the old server to the new server and 
> noticed that every 5-6 transfer the speeds would slow down to only 
> 1-2MB/s and sometimes stop all together.
> 
> I suspected this was due to the cache/memory getting filled up so XFS 
> has to write the changes to the sata drive. I tried to turn off 
> write-cache and nobarriers but still have the same problem..
> 
> When i try it on the ext3 filesystem it runs at a constant transfer speed.
> 
> Is this normal with the XFS filesystem?
> 

We looked at this a bit on irc tonight and even streaming direct IO to a 
contiguous xfs file was going very very slow.  I think he also tested 
direct IO reads from the device, and found them slow as well, so the 
problem may well be beneath xfs.

-Eric