We had connection issues (this thread) (server not found / cannot display webpage) especially during quiz taking so we upgraded to 2.6.3. That seemed to solve connection issues for a while, but now they have resurfaced. It is a Virtual machine. When the VM is unresponsive, other VMs on that machine still are fine.

I note that while creating a snapshot, system resources are so great that it causes similar connectivity issues. However, even when load is normal (.13, 37% memory usage) there are still intermittent pings that don't connect. I do notice spikes on the VM admin but nothing that seems high enough to be problematic or seemingly that really lines up with the issues we have.

We're running Ubuntu 12.04.1 with 4GB RAM, max 300 users.

I changed /etc/apache2/apache2.conf max clients (3x) from 150 to 255

I am installing all ubuntu updates presently as something to try...

What can I try to further troubleshoot?

I enabled performance info and pasted below. Does this give any clues?

3.968453 secs
RAM: 57MB
RAM peak: 58.3MB
Included 188 files
Contexts for which filters were loaded: 3
Filters created: 3
Pieces of content filtered: 13
Strings filtered: 0
get_string calls: 627
DB reads/writes: 923/17
DB queries time: 3.05942 secs
ticks: 397 user: 91 sys: 5 cuser: 0 csys: 0
Load average: 0.19 Session (core\session\file): 6.4KB
Caches used (hits/misses/sets)
core/databasemeta** static acceleration **: 12 / 3 / 0cachestore_file: 3 / 0 / 0
core/string** static acceleration **: 568 / 64 / 0
cachestore_file: 64 / 0 / 0
core/coursemodinfo
cachestore_file: 2 / 0 / 0
core/yuimodules
cachestore_file: 3 / 0 / 0
core/repositories
cachestore_static: 0 / 10 / 20
core/groupdata** static acceleration **: 1 / 1 / 0
cachestore_file: 1 / 0 / 0
core/langmenu** static acceleration **: 0 / 1 / 0
cachestore_file: 1 / 0 / 0
Total: 655 / 79 / 20 

Thank you.