Is copying the /var/lib/mysql directory a good alternative to mysqldump?

Question

Since I'm making a full backup of my entire debian system, I was thinking if having a copy of /var/lib/mysql directory is a viable alternative to dumping tables with mysqldump.

• are all informations needed contained in that directory?
• can single tables be imported in another mysql?
• can there be problems while restoring those files on a (probably slightly) different mysql server version?

Automatic

Doing this for years, no inconsistency! – Etom

Percona has a tool that basically takes this approach for doing "hot backups" of running servers: percona.com/doc/percona-xtrabackup/2.1 – Weekday

Answer 1

• Yes
• Yes if the table is using the MyISAM (default) engine. Not if it's using InnoDB.
• Probably not, and if there is, you just need to execute mysql_upgrade to fix them

To avoid getting databases in a inconsistent state, you can either shutdown MySQL or use LOCK TABLES and then FLUSH TABLES before the backup. The second solution is a little better because the MySQL server will remain available during the backup (albeit read only).

Ripplet

Thanks everybody for this solution. It's cut out at least an hour of re-importing time ! And if you want to do it into one instruction: Type "FLUSH TABLES WITH READ LOCK;". – Pernicious

Can you go into details on the answer for "can single tables be imported into another mysql"? "Yes so long as it's MyISAM" is a rather sparse answer. – Bradley

Answer 2

This approach is only going to work safely if you shut the database down first. Otherwise you could well end up in an inconsistent state afterwards. Use the /etc/init.d/mysql stop command first. You can then restart it after the backup is taken.

Patti

Answer 3

It's perfectly OK as long as you shut down the MySQL sever first and use exactly the same version to retrieve the "backup". Otherwise it isn't.

Matteson

Answer 4

For a complete discussion of the 2 strategies, you need to read this: https://dev.mysql.com/doc/refman/5.5/en/backup-types.html

The currently best free and open-source solution seems to be Percona's: http://www.percona.com/software/percona-xtrabackup

Araxes

Answer 5

I'll go with a strong NO.

From my experience, backing up/restoring raw mysql data files can be used only on the same os/server version. It does not work cross platform (eg. ubuntu/macos) with same server versions nor if mysql server versions are different on same platform.

Percona XtraBackup (innobackupex) from Percona MySQL distro will let you do live & differential mysql backup and serve you the backup files that can be restored by copying to /var/lib/mysql/. You need to be running Percona Server for MySQL to use all of this.

Yacano