[OpenAFS] OpenAFS speed

[Hartmut Reuter]

There are several possible reasons for slow file transfer. To find out 
which ones are important I would try the following tests:

1) Find out how fast your RAID system is by creating a /vicepa/tmp and 
writing your file directly in there. But be sure your program does a 
fsync() call otherwise you only measure how fast it writes into the I/O 
buffers. The RAID 5 performance should be at least 30 MB/s, good 
IDE-RAID5 systems go up to 100 MB/s

2) The client cache: the local disk on the client may be not very fast 
and also already busy by other activities on the machine. I found best 
results using a ramdisk cache. In our Linux-cluster with Gbit Ethernet 
and ramdisk cache I see transfer rates of > 25 MB/s into AFS.

3) Net topology and load. What do you get out of "iperf" between your 
client and server?

All 3 results combined may explain the slow transfer rate.

-Hartmut

Lukas Kubin schrieb:
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> I'm running OpenAFS version 1.2.9-2 (Debian package) on a 2-processor
> machine, where "vicepa" is on RAID5 (Adaptec) container installed. The
> filesystem used is ext3.
> When I try to write one 700 MB large file to AFS, it takes more than 3
> minutes to complete. I tried this both locally (by generating the file
> with "dd" from /dev/zero) and through 100 Mbps network. The result was the
> same.
> Is this normal feature of AFS or do I have to do some tuning?
> Thank you.
> 
> lukas
> 
> - -- 
> Lukas Kubin
> 
> phone: +420596398285
> email: kubin@opf.slu.cz
> 
> Information centre
> The School of Business Administration in Karvina
> Silesian University in Opava
> Czech Republic
> http://www.opf.slu.cz
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> 
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-- 
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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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