[OpenAFS] poor client performance on linux

Dimitris Zilaskos dzila@tassadar.physics.auth.gr
Sun, 21 May 2006 12:39:47 +0300 (EEST)

 	Hello ,

 	I am using openafs 1.4.1 with linux Afsd runs with 
-stat 4000 -dcache 4000 -daemons 6 -volumes 256 -files 50000 -chunksize 
 	The client system serves as an anonymous ftp server, with around 
80 ftp server instances concurrently accessing various files on afs. A 
particular popular file X is around 2.4 GB large. Other popular files have 
sizes starting from 2 Mbytes up to 700.
 	A test when the afsd  has just started with just one ftp 
server instance transferring file X achieves speeds 10-20 MB/sec, with 
12-15 being the average. Repeated transfers of the same file again with one
ftp client exhibit more or less the same results. Test was made with wget 
and lftp. Pure-ftpd is the ftp server software.
 	When around 80 ftp server instances access afs performance drops 
to around 3-60 KB/sec for each one. Load average exceeds 20 and can reach 
80. Disk activity is quiet intensive but the system is unable to push 
more than 2.5 MB/sec to the network. Killing all ftp server instances and 
again testing with only one improves things a bit: speed flactuates between
1-7 MB/sec. Restarting afsd brings performance back to 10+ MB/sec.
 	I switched the afs  cache from one devoted ata100 disk to a 4 disk 
ata100 striping raid but nothing changed.
 	AFS server is p4@ 2.6GHz, 1GB ram 4 sata disks on striping raid. 
Its load rarely exceeds 0.5. The ftp server is p4 celeron @ 2GHz, 512MB 
ram, afs cache tested on single disk and 4 disk raid. It does not 
consume any of its swap at all.All are connected at the same Gigabit 
switch. The clients accessing the ftp server are mostly DSL 
users and when afs is not involved they usually peek at around 
3.5 MB/sec.

 	Can anyone think of anything I can do to improve performance?

 	Best regards ,


Dimitris Zilaskos

Department of Physics @ Aristotle University of Thessaloniki , Greece
PGP key : http://tassadar.physics.auth.gr/~dzila/pgp_public_key.asc
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