[Koha] Regular performance problems

[Chris Hobbs]

  Our koha server regularly grinds to a halt, preventing use of the web 
gui and even making it near impossible to log into via ssh. One minute 
load average on the server has spiked into at least the 80s, where it 
normally hovers around 1.

If I'm patient, after about 15 minutes the system becomes usable again.

Where should I begin looking for the trouble?

The system is running on a VMWare ESX host. It's been given two vCPUs 
and 6GB of RAM. The host is not starved for resources, so I think I can 
exclude it from the equation. Other VMs running on the same host are not 
affected.

Koha is version 3.01.00.140 (last beta before 3.2). The server is Ubuntu 
9.10. We have ~200,000 items and ~100,000 biblios.

I was able to capture a process list during the last event (this AM), 
and saw that I had 95 instances of apache started. At the moment, with 
things working smoothly, I have only 14.

I've also run mysqltuner.pl in order to locate potential bottlenecks 
with the db, and the only glaring issues I have are:

1) Lots of joins without indexes (811 since db restart this morning)
2)  Temporary tables created on disk: 45% (6K on disk / 15K total)
   I've set innodb_buffer_pool_size = 1G in my.cnf, but still the system 
keeps creating these tables on disk, which certainly can't be helping 
anything.

OK, any ideas? Other troubleshooting info I can provide? It's gotten to 
the point that we're losing a decent amount of time every day to this issue.

Thanks so much in advance!

-- 
Chris Hobbs
Director, Technology
New Haven Unified School District

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