On a sever using Plesk 11.5 (Centos 6), i recently upgraded MySQL and PHP using the atomicorp repo, and ran into problems with MySQL refusing to start after the upgrade.

For those who don’t know, the atomicorp repo can be added using the following commands:

wget -q -O – http://www.atomicorp.com/installers/atomic | sh

yum update

Everything seemed to go smoothly, but the mysqld service refused to start after that..

This is what the log said:

InnoDB: The InnoDB memory heap is disabled
InnoDB: Mutexes and rw_locks use GCC atomic builtins
InnoDB: Compressed tables use zlib 1.2.3
InnoDB: Using Linux native AIO
InnoDB: Warning: io_setup() failed with EAGAIN. Will make 5 attempts before giving up.
InnoDB: Warning: io_setup() attempt 1 failed.
InnoDB: Warning: io_setup() attempt 2 failed.
InnoDB: Warning: io_setup() attempt 3 failed.
InnoDB: Warning: io_setup() attempt 4 failed.
InnoDB: Warning: io_setup() attempt 5 failed.
InnoDB: Error: io_setup() failed with EAGAIN after 5 attempts.
InnoDB: You can disable Linux Native AIO by setting innodb_use_native_aio = 0 in my.cnf
InnoDB: Fatal error: cannot initialize AIO sub-system
[ERROR] Plugin ‘InnoDB’ init function returned error.
[ERROR] Plugin ‘InnoDB’ registration as a STORAGE ENGINE failed.
[ERROR] Unknown/unsupported storage engine: InnoDB
[ERROR] Aborting

It turns out that i needed to add the following directives in the my.conf file (found in /etc/):

innodb_use_native_aio=0
innodb_buffer_pool_size=2M
innodb_additional_mem_pool_size=500K
innodb_log_buffer_size=500K
innodb_thread_concurrency=2

after restarting the mysqld service (using the command: service mysqld restart), everything was back to normal.

for good measure, i also ran the following command:

mysql_upgrade -uadmin -p`< /etc/psa/.psa.shadow `

Hope this helps!