It seems that my Q2A instance that used to run stable is now randomly going down every couple weeks or so with no explainable reason.
A system reboot seems to fix the problem. I'm running on Amazon EC2/Ubuntu - any thoughts on how to diagnose/check what might the issue might be?
[Update: It's happened quite a few times now. Every week or so, I check my Q2A instance and it seems to be having a problem with a database connection. I reset the server and it fixes itself.]
[Update again: I've found some stuff in the logs as follows:
root@ip-10-225-170-15:/var/log/mysql# cat error.log
131211 12:07:13 [Note] Plugin 'FEDERATED' is disabled.
131211 12:07:13 InnoDB: The InnoDB memory heap is disabled
131211 12:07:13 InnoDB: Mutexes and rw_locks use GCC atomic builtins
131211 12:07:13 InnoDB: Compressed tables use zlib 188.8.131.52
131211 12:07:13 InnoDB: Initializing buffer pool, size = 128.0M
InnoDB: mmap(137363456 bytes) failed; errno 12
131211 12:07:13 InnoDB: Completed initialization of buffer pool
131211 12:07:13 InnoDB: Fatal error: cannot allocate memory for the buffer pool
131211 12:07:13 [ERROR] Plugin 'InnoDB' init function returned error.
131211 12:07:13 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
131211 12:07:13 [ERROR] Unknown/unsupported storage engine: InnoDB
131211 12:07:13 [ERROR] Aborting
When I try to restart the `mysql' service:
root@ip-10-225-170-15:~# service mysql start
start: Job failed to start
When I restart the Amazon instance, it works fine. My googling reveals that it appears to be some kind of memory problem (probably due to the fact that I haven't allocated enough RAM to the server etc.)]