Amazon EC2, mysql aborting start because InnoDB: mmap (x bytes) failed; errno 12
amazon-ec2, mysql
Solution
I met the same problem when I tried to run a wordpress on my micro instance without RDS.
Adding a Swap page solved the problem for me.
You can follow steps below to setup the swap space.
If it still doesn't work for you, consider using the RDS service.
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I copied the content of the blog for the record. Credit goes to the blog author pmoubed:
Amazon EC2 Micro Instance Swap Space - Linux
I have a Amazon EC2 Linux Micro instance. Since Micro instances have only 613MB of memory, MySQL crashed every now and then. After a long search about MySQL, Micro Instance and Memory Managment I found out there is no default SWAP space for Micro instance. So if you want to avoid the crash you may need to setup a swap space for your micro instance. Actually performance wise is better to enable swap.
Steps below show how to make a swap space for your Micro instance. I assume you have AWS Account with a Micro instance running.
- Run `dd if=/dev/zero of=/swapfile bs=1M count=1024`
- Run `mkswap /swapfile`
- Run `swapon /swapfile`
- Add this line `/swapfile swap swap defaults 0 0` to `/etc/fstab`
Step 4 is needed if you would like to automatically enable swap file after each reboot.
Some useful command related to SWAP space:
$ swapon -s
$ free -k
$ swapoff -a
$ swapon -a
References:
- http://www.thegeekstuff.com/2010/08/how-to-add-swap-space/
- http://cloudstory.in/2012/02/getting-the-best-out-of-amazon-ec2-micro-instances/
- http://cloudstory.in/2012/02/adding-swap-space-to-amazon-ec2-linux-micro-instance-to-increase-the-performance/
- http://aws.amazon.com/ec2/instance-types/
Problem
I have a micro instance server on EC2 based on this mysql server fails frequently and for the third time mysql server is gone. The logs only shows ``` 120423 09:13:38 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended 120423 09:14:27 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 120423 9:14:27 [Note] Plugin 'FEDERATED' is disabled. 120423 9:14:27 InnoDB: The InnoDB memory heap is disabled 120423 9:14:27 InnoDB: Mutexes and rw_locks use GCC atomic builtins 120423 9:14:27 InnoDB: Compressed tables use zlib 1.2.3 120423 9:14:27 InnoDB: Using Linux native AIO 120423 9:14:27 InnoDB: Initializing buffer pool, size = 512.0M InnoDB: mmap(549453824 bytes) failed; errno 12 120423 9:14:27 InnoDB: Completed initialization of buffer pool 120423 9:14:27 InnoDB: Fatal error: cannot allocate memory for the buffer pool 120423 9:14:27 [ERROR] Plugin 'InnoDB' init function returned error. 120423 9:14:27 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 120423 9:14:27 [ERROR] Unknown/unsupported storage engine: InnoDB 120423 9:14:27 [ERROR] Aborting ``` What is really `failed; errno 12`? And how could I give more space/memory or whatever needed to make this fixed. I fix this each time by rebooting the whole system and deleting all logs and restart the mysql server. But I know something is wrong with my configuration. Also my `my.cnf' is like below : ``` [mysqld] # Settings user and group are ignored when systemd is used. # If you need to run mysqld under different user or group, # customize your systemd unit file for mysqld according to the # instructions in http://fedoraproject.org/wiki/Systemd # max_allowed_packet=500M datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 innodb_buffer_pool_size = 512M [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid ```