[Samba] Very slow write performance to RAID

Jeremy Allison jra at samba.org
Mon Jul 25 14:28:33 MDT 2011

On Mon, Jul 25, 2011 at 01:06:48PM -0400, Kevin Taylor wrote:
> We have a RAID set up as our main fileserver (running samba 3.0.33 on linux, CentOS 5). The main disk area is an XFS partition of about 8TB. I'm using iostat to monitor disk I/O since we've gotten complaints about speed and I'm noticing that when I write something to the samba share, the write speed is horrible. For a 15GB file it is reporting to finish in about 20 minutes.
> iostat reports very little write I/O...on the level of maybe 7 write i/o's every 5 seconds or so.
> If I were to read .5GB of data off of the samba share, it transfers quickly (and I see 300 reads/s through iostat)...which would be about normal.
> Any idea of why I'm getting such lousy write speed? 

Test using a modern (i.e. much later than 3.0.33) smbclient.

This pipelines writes so you should see much greater
throughput if it's the client that's at fault. What
client are you using ?


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