[Building Sakai] How does Sakai respond to an overloaded database?

[john.bush at rsmart.com]

What db are you using? Oracle or mysql?

Sent from my commodore 64

On Dec 15, 2009, at 9:47 AM, "R.P. Aditya" <rpaditya at umich.edu> wrote:

> On 2009-12-09, Joshua Swink <joshua.swink at gmail.com> wrote:
>> We had a near-outage recently when the database server got heavily
>> loaded. We had an unprecedented number of users on Sakai. Sakai was
>> behaving like this:
>>
>> - very slow page loads (up to 10 minutes)
>> - system load factor very high (10-15)
>> - database connection pool being exhausted (one tomcat did exhaust it
>> and needed to be restarted; the others survived)
>>
>> Obviously we need to add better hardware.
>>
>> What I want to know is whether the application's behavior can be
>> attributed to the user load alone, or if the database's increased
>> response time could be responsible. One hypothesis is that the
>> application servers would have been fine if the database had been
>> responding in a timely fashion. Another is that the usage would have
>> led to Sakai bogging down even if the db had been fine.
>>
>> Any thoughts?
>
> we've definitely seen this happen and typically the db connection pool
> fills up and the appserver is unresponsive to most Sakai requests  
> (which
> need the db, which is most anything to do something useful) --  
> depending
> on the problem, adding more connection pool connections might help but
> probably just buys you a few seconds before those extra connections  
> are
> eaten up, but you also increase load on the db handling extra
> connections so unless you know that the load came from elsewhere on  
> the
> db server, you shouldn't exacerbate the issue from Sakai...
>
> Adi
>
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