Frequently Asked Questions¶
Do I need an InnoDB Hot Backup license to use Percona XtraBackup?¶
No. Although innobackupex is derived from the same GPL and open-source
wrapper script that InnoDB Hot Backup uses, it does not execute ibbackup,
and the xtrabackup binary does not execute or link to ibbackup. You
can use Percona XtraBackup without any license; it is completely separate
from InnoDB Hot Backup.
What’s the difference between innobackupex and innobackup?¶
The innobackupex binary is a patched version of the Oracle innobackup script (renamed mysqlbackup). They are similar, and familiarity with innobackup might be helpful.
Besides the available options for specific features of innobackupex, the main differences are:
-
Prints to
STDERRinstead ofSTDOUTwhich enables theinnobackupex --streamoption -
Detects the configuration file -
my.cnf- is automatically (or set withinnobackupex --defaults-file) instead of requiring the configuration file as the the first argument -
Defaults to xtrabackup as binary to use in the
innobackupex --ibbackup
See The innobackupex Option Reference for more details.
Which Web-based backup tools are based on Percona XtraBackup?¶
Zmanda Recovery Manager is a commercial tool that uses Percona XtraBackup for Non-Blocking Backups:
“ZRM provides support for non-blocking backups of MySQL using Percona XtraBackup. ZRM with Percona XtraBackup provides resource utilization management by providing throttling based on the number of IO operations per second. Percona XtraBackup based backups also allow for table-level recovery even though the backup was done at the database level. This operation requires the recovery database server to be Percona Server for MySQL with XtraDB.”
xtrabackup binary fails with a floating point exception¶
In most of the cases this is due to not having installed the required libraries (and version) by xtrabackup. Installing the GCC suite with the supporting libraries and recompiling xtrabackup will solve the issue. See Compiling and Installing from Source Code for instructions on the procedure.
How does xtrabackup handle the ibdata/ib_log files on restore if they are not in the MySQL datadir?¶
If the ibdata and ib_log files are located in different
directories outside of the datadir, you move them to their proper place after the logs have been applied.
Backup fails with Error 24: ‘Too many open files’¶
This error usually occurs when the database being backed up contains large amount of files and Percona XtraBackup can’t open all of them to create a successful backup. In order to avoid this error the operating system should be configured appropriately so that Percona XtraBackup can open all its files. On Linux, this can be done with the ulimit command for specific backup session or by editing the /etc/security/limits.conf to change it globally
Note
The maximum possible value that can be set up is 1048576 which is a hard-coded constant in the Linux kernel.
How to deal with skipping of redo logs for DDL operations?¶
To prevent creating corrupted backups when running DDL operations, Percona XtraBackup aborts if it detects that redo logging is disabled. In this case, the following error is printed:
[FATAL] InnoDB: An optimized (without redo logging) DDL operation has been performed. All modified pages may not have been flushed to the disk yet.
Percona XtraBackup will not be able to take a consistent backup. Retry the backup operation.
Note
Redo logging is disabled during a sorted index build
To avoid this error, Percona XtraBackup can use metadata locks on tables while they are copied:
-
To block all DDL operations, use the
xtrabackup --lock-ddloption that issuesLOCK TABLES FOR BACKUP. -
If
LOCK TABLES FOR BACKUPis not supported, you can block DDL for each table before XtraBackup starts to copy it and until the backup is completed using thextrabackup --lock-ddl-per-tableoption.