[OpenAFS] Cache manager parameter questions

Mike Polek mike@pictage.com
Thu, 07 Jul 2005 09:26:53 -0700

Silly question... how many simultaneous file transfers
can a 64M memcache handle? And what parameters would
affect that?

AFS client is an FTP server using memcache. The system routinely
has 100 users or more. We're starting to see FTP clients kick back
messages like "Stale NFS file handle"... which of course is a lie...
but I'm thinking that there is a resource that is being overrun
in the cache manager.

-memcache -blocks 65536 -chunksize 16 -stat 2800 -daemons 3 -volumes 128

I can't increase the size of the memcache because attempting to
valloc more memory results in an oops most of the time.
I'm considering adjusting the other parameters like

-memcache -blocks 65536 -chunksize 18 -stat 4000 -daemons 5 -volumes 512

Am I going to have problems if I increase chunksize because there
will be fewer dcache entries? Are there limits to how high I can
set the other parameters when using memcache? I know it's more of
an art than a science (at least it seems that way... or maybe
voodoo.... ), but if anyone has experience using memcache on a server
with a high load, I'd love to hear about it.

Mike Polek
Pictage, Inc.