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Backup Where

Table of contents
  1. 1. Backup Where

Backup Where

This page specifies where the backup images for the backup set will be stored, and how long to retain them.

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Destination Directory
Regardless of where the remote MySQL server is hosted, backups are stored under the backup directory of the local machine where ZMC runs. The default /var/lib/mysql-zrm. If you specify another directory, you must create it yourself on both the ZRM server and the MySQL server, and ensure that its permission settings allow read/write access to the mysql backup user. The directory used on the MySQL server and ZRM server cannot be the same i.e cannot be the same CIFS or NFS share.

The recommended practice is to mount a filesystem at /var/lib/mysql-zrm. Use local, NFS, or CIFS mounted storage for storing MySQL backup data. The MySQL backup data can be migrated to other storage devices using Network-based backup and recovery utilities such as Amanda. If you are using NFS or CIFS storage as Destination directory, the root user and mysql user should have privileges to read and write to this directory.

You must allocate sufficient disk space to store the MySQL databases. If sufficient disk space is not available, the backup run will fail. The destination directory should have at least 150% of uncompressed backup space available for a successful backup run. This additional space is required even when backups are configured for compression, since the additional space is used for compression during the backup run. The additional space is freed after the backup run.

Example: Backup set "daily" requires 150GB of disk space for uncompressed backups and backup image upon compression are 100GB. The backup directory filesystem should have at least 225GB (1.5 * 150GB) for space.
After backup run is completed, only 100GB of disk space will be used.
The destination directory must not be under autofs controlled mount point because snapshot based backups mount the file system or storage snapshot under the Destination directory.
Temporary Directory

The default is to use the OS-specified temporary directory ($TMPDIR on Linux). It is recommended that the default value is changed so that sufficient temporary space if available for backup and restoration. In any case, the directory must exist on both the client and server, and have permissions set to allow read/write access to the MySQL backup user. If $TMPDIR is defined differently on the ZRM server and the MySQL server, you must explicitly set the path here and make sure that directory exists on both machines. In case of Solaris /tmp is memory based file system and filling it up will cause processes to run out of memory. So, default value must be changed.

The disk space used in the temporary directory depends on the backup method.

Logical backup and Snapshot backup - Few kilobytes are required during backup and size of full backup image is required during restoration. The space is required on the ZRM server.

Raw backup (using mysqlhotcopy) - Size of full backup image plus 10% is required during backup as well as restoration. The space is required on the MySQL server.

Xtrabackup tool - During backup, disk space equal to full size of backup image is required on the MySQL server. During restoration of full backups, space equivalent to backup image size is required on the ZRM server. If restoration involves full backup, differential/chained differential backups, size of temporary directory on the ZRM server must be sum of all backup images. Streaming backup mode does not require disk space equal to full backup image size on the MySQL server.

MySQL Enterprise Backup - Size of full backup image plus 10% is required during backup on mysql server.
During restoration of full backups, space equivalent to backup image size is required on the ZRM server. If restoration involves full backup, differential/chained differential backups, size of temporary directory on the ZRM server must be sum of all backup images. Space is not required on the MySQL server. Streaming backup mode does not require disk space equal to full backup image size on the MySQL server.

Retention Policy 
 
A retention policy sets the limit of the period for which the backup set will be retained. Images older than the retention policy specified are automatically purged. The retention policy for a backup image is stored in the backup index at the time of backup. So, changing the retention policy will not change the retention policy of backup runs that have been completed. If the retention policy is not specified, the backup images are retained forever.

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