[OpenAFS] strange disk write activity compared to network bandwidth

Sophana sophana@zizi.ath.cx
Mon, 27 Aug 2007 16:39:49 +0200


I'm evaluating openafs 1.4.4 performance on centos 4
I noticed some strange things.

I'm doing a simple svn checkout (meaning write to afs) (server on the
lan)  of a lot of source files (quite small...) (about 50mbyte+svn
overhead ~= 100mbyte)
When using gkrellm, I can see the disk write bandwidth at at a high
level (> 15mbyte/s), almost no read, and the network bandwidth is MUCH
lower (less than 1mbyte/s). It seem that the server is busy making a LOT
of disk writes, that are about 10 to 20 times the volume of the real
data being written.

And of course, it is quite slow:
3min on remote afs client (standard cache settings)
2m30 on the server itself

21s when checking out to an ext3 partition.

Has someone an explanation of that behaviour? and a workaround?
It seems that when I tested openafs 1.2.X a long time ago, I think there
were not such strange behaviour.