Starting MySQL (Percona Server). ERROR! The server quit without updating PID file – Percona

I recently experienced this error on a DigitalOcean node with 512MB ram. The full error below:

Starting MySQL (Percona Server). ERROR! The server quit without updating PID file (/var/lib/mysql/test2.pid)

The log had the following errors logged

2015-05-25 03:46:27 3518 [Note] InnoDB: Initializing buffer pool, size = 128.0M
InnoDB: mmap(137363456 bytes) failed; errno 12
2015-05-25 03:46:27 3518 [ERROR] InnoDB: Cannot allocate memory for the buffer pool
2015-05-25 03:46:27 3518 [ERROR] Plugin 'InnoDB' init function returned error.
2015-05-25 03:46:27 3518 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2015-05-25 03:46:27 3518 [ERROR] Unknown/unsupported storage engine: InnoDB
2015-05-25 03:46:27 3518 [ERROR] Aborting

Turns out the VPS did not have enough RAM to allocate to the InnoDB plugin.

One fix is to disable InnoDB, because this was a test node and I really didn’t need InnoDB I was able to disable it by adding the following to my.cnf

[mysqld]
innodb=OFF 
ignore-builtin-innodb 
skip-innodb
default-storage-engine=myisam 
default-tmp-storage-engine=myisam