[horde] still having problems with dropped sessions

Kevin Konowalec webadmin at ualberta.ca
Wed Mar 14 21:07:15 UTC 2007

Yeah that's exactly what I was thinking... that's why I was asking  
how much session data is actually stored per user so I can estimate  

On Mar 14, 2007, at 2:11 PM, Majeed wrote:

> Im still in the process of planning our new webmail system based  
> around
> memcached sessions. Maybe others can correct me, but I have a hard  
> time
> seeing 1gb of memory for session data for 3600-4000 concurrent mail
> users even being close to enough. Even if each user, during peak  
> times,
> had .5mb worth of session data, it would still be quite a bit more  
> than
> 1gb. However, I'm not an expert. Yet :)
> Good luck
> 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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