Kai Moritz wrote:
What are your data rates in MB/s?
scp says: 4.6MB/s
Isn't great either. So may be you have some other problems in your network?
When I do a scp of a 100 MB file to my laptop I get ~ 8 MB/s and there
is in parallel running a remote rsync with about another .7 MB/s in both
directions (rsyncd and AFS).
So I normally get the full 100 Mbit/s bandwidth when I write into AFS or
read from AFS: >= 10 MB/s.
If you are on a fast network (Gbit Ethernet, Inifiband ...) a disk cache
may be remarkably slower than the network. In this case memory cache can
help.
I haven't tried that yet, becaus in the file /etc/openafs/afs.conf of
my Debian Etch installation there is a comment that says:
# Using the memory cache is not recommended. It's less stable than the disk
# cache and doesn't improve performance as much as it might sound.
We are using here in our Linux clusters and on the high performance AIX
power 4/5 machines memcache without problems.
It's my special OpenAFS-1.4.4 with OSD support which is expected to
arrive soonly in the OpenAFS CVS. But I suppose also the normal
OpenAFS-1.4.4 should work without problems with memcache
Hartmut
Another point is chunk size. The default (64 KB) is bad for reading
where each chunk is fetched in a separate RPC. with disk cache bigger
chunks (1 MB) can be recommanded, anyway. For memory cache of, say, 64
MB you would limit the number of chunks to only 64 which is certainly
too low.
With automatically choosen values writing a 128 MB file in AFS takes
about 44-45 seconds.
On that machine I have a 3 GB cache.
With the following options, which a have taken from an example in a Debian
Configfile, writing the 128 MB file takes about 48 seconds :(
-chunksize 20 -files 80000 -dcache 10000 -stat 15000 -daemons 6 -volume
s 500 -rmtsys
Greetings kai
--
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Hartmut Reuter e-mail [EMAIL PROTECTED]
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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