I concur with Richard that the simplest method I have found is to simply
change session.save_path in your php.ini file to an NFS mount. In my own
benchmarks, under a moderate simulated web load with hosts mounted against
the NFS share this performed much better than when trying to use a rather
simple method of storing it in a MySQL back-end (there is of course a lot
of room for optimization on the later which I did not consider at the time
as was looking for simplicity). This seemed to peak at around 6 concurrent
web hosts against the NFS mount point, though I only had 7 physical hosts
to play with and so don't have insight into the drop-off beyond 7. I can
probably dig out my project paper detailing the specs under this testing if
you think it might be of benefit to you.
In theory if you used iSCSI on the back-end for the shared storage with a
clustered file system (I am thinking GFS, as I don't believe OCFS is
designed to perform well with the way PHP stores the session files) you
could scale this well beyond 6 hosts without suffering any performance
degradation.
If you have the luxury of a BigIP, then you can start to do clever things
such as using embedded cookies to leverage sticky sessions in pinning
someone to a specific host in the cluster, etc. Of course the expense of
such puts out of reach of most open source projects and hobbyists.
Best of luck!
Chris
On Wed, 14 May 2008 17:46:11 -0400, ref <
tbs@...> wrote:
>
> we have three front end web servers that serve millions of pages a month
> via apache2/php5, and
> use an NFS server to hold all session information. We had to do this as
> the
> front end servers are behind an SNMP balanced bigIP loadbalancer. we did
> some tests
> first and for us it proved faster to get the flat files from NFS than to
> get the
> session data from a shared DB (though I must add that the NFS mounted
> server is
> ALSO the DB server, so it was actually a good test).
>
> Richard
>
>
>
> On Wed, 2008-05-14 at 11:39 -0400,
markw@... wrote:
>> Are there any admins/architects that have multiple web servers using PHP
>> and are sharing sessions.
>>
>> I have an open source project I've been trying to get going for a while
>> now and I'd like to solve the major issues for this type of deployment.
>>
>
>
>
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