[horde] still having problems with dropped sessions

[Liam Hoekenga]

Kevin -

We've got 6GB of memcache for use in our pool.  4 x 1.5GB instances of 
memcached, spread across 2 servers.  We decided on the break down due to 
the 2GB per process memory limit in 32bit linux (that, and the machines 
only have 4gb of physical RAM).

Liam

Kevin Konowalec wrote:
> Horde: 3.1.2
> Imp: H3 (4.1.2)
> Turba: H3 (2.1.1)
> PHP Version: 4.4.1
>
> So I've added a second memcached instance of 512MB (for a total of  
> 1024MB) but we're still seeing sessions being dropped fairly  
> frequently (and no messages in the logs are even remotely helpful).   
> By "dropped" I mean the user will be logged in and reading or writing  
> mail and suddenly he/she will find themselves booted back to the  
> login screen without explanation.  We have roughly 3600-4000  
> concurrent users at peak volume - is 1Gig enough memcached size?  And  
> if it's not a memcached problem, where else can anyone suggest we  
> look as the cause?  Since this is the busiest time of the year I  
> suspect that it's a function of load... but I'm not sure which part  
> of the system is failing because of it.  And it's strange in that  
> sometimes you can leave yourself logged in all night and your session  
> will still be there (as you'd expect) but other times you can be  
> booted out several times repeatedly without warning.
>
> I'm not sure if it's an indicator of the way students use the system  
> (ie logging in to check their mail several times a day) or if it's a  
> result of this repeated login problem but my log analysis showed that  
> the number of distinct users logging in per day is dwarfed by the  
> total number of logins per day at a ratio of about 3:1 and growing.
>
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