Nate Gordon wrote:
On Tue, Nov 17, 2009 at 6:25 PM, Jason Edgecombe <[email protected]>wrote:
Derrick Brashear wrote:
On Tue, Nov 17, 2009 at 5:09 PM, Jason Edgecombe
<[email protected]> wrote:
Hi Everyone,
Our webserver has been brought to a crawl many times over the last few
weeks. I suspect it's an AFS bottleneck somewhere. I appreciate any help
I can get.
The web server runs solaris 9 w/openafs 1.4.1.
is that correct?
that's not even worth debugging. lots of things have been fixed since
then, this could be something new or one of a dozen things already
fixed.
Yes, 1.4.1 is correct.
I'm wondering if increasing the number of daemons would help. The afsd man
page mentions that more than 5 or six daemons isn't helpful. I suspect that
the number of apache daemons (75) is overwhelming the number of afsd
threads/daemons (5).
https://lists.openafs.org/mailman/listinfo/openafs-info
As someone who also runs AFS as the backend to a webserver, I can understand
your problems. My problems stem more specifically from PHP on AFS and that
PHP the language feels it is necessary to perform lots and lots of trivial
stat operations. I have theorized that there are some global locking issues
floating around the internals of the kernel module that cause problems on
multithreaded systems under high load. Unfortunately I'm a web geek and
less of a kernel programmer, so I have had limited success in tracking down
and fixing the problem. Unfortunately I don't think daemons will be
terribly useful. My understanding is that they aren't used in local cache
operations, and only used for remote operations when things are getting
behind. I'm currently running 6 daemons for 500 apache threads.
I would also echo Derrick's comment on the age of the version you are
using. I have noticed some significant improvements as the 1.4 branch has
gone on.
Thanks for the info about the daemons. We have lots of sites running
Joomla and PHP. I noticed a 5% vcache miss rate compared to a 1% dcache
miss rate on our web server. That corroborates your statement about stat
calls.
Derrick, I have 1.4.10 with the
STABLE14-background-fsync-consistency-issues patch already compiled and
ready to deploy. Would that be new enough to consider debugging?
I'm planning on upgrading our web server to 1.4.10 in December.
Jason
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