Merge lp:~hrvojem/percona-xtrabackup/bug1158243-2.0 into lp:percona-xtrabackup/2.0

[Hrvoje Matijakovic]

[Alexey Kopytov (akopytov)]

  - s/One of the ways how to verify/One way to verify/ would probably be
    a better wording (with the "I am not a native speaker" disclaimer
    attached)
  - would linking to
    http://www.percona.com/doc/percona-toolkit/pt-table-checksum.html
    (i.e. excluding the version) be better, so it redirects to the
    latest version docs at all times?
  - I would clarify that the master replication server in this recipe
    may be either the original server where the backup was taken, or
    another test server created by using a different backup method (such
    as cold backup, mysqldump or LVM snapshots) at the original server.

review: Needs Fixing

[Alexey Kopytov (akopytov)]

review: Approve

[Stewart Smith (stewart)]

Alexey Kopytov <email address hidden> writes:
> Review: Needs Fixing
>
> - s/One of the ways how to verify/One way to verify/ would probably be
> a better wording (with the "I am not a native speaker" disclaimer
> attached)

With the "I am a native speaker" disclaimer: it is better wording :)

--
Stewart Smith

=== modified file 'doc/source/how-tos.rst'
--- doc/source/how-tos.rst	2012-11-19 02:09:59 +0000
+++ doc/source/how-tos.rst	2013-04-30 12:46:25 +0000
@@ -38,6 +38,7 @@
    :maxdepth: 1
 
    howtos/setting_up_replication
+   howtos/backup_verification
 
 .. _aux-guides:
 
 
=== added file 'doc/source/howtos/backup_verification.rst'
--- doc/source/howtos/backup_verification.rst	1970-01-01 00:00:00 +0000
+++ doc/source/howtos/backup_verification.rst	2013-04-30 12:46:25 +0000
@@ -0,0 +1,73 @@
+.. _backup_verification:
+
+====================================================
+ Verifying Backups with replication and pt-checksum
+====================================================
+
+One way to verify if the backup is consistent is by setting up the replication and running `pt-table-checksum <http://www.percona.com/doc/percona-toolkit/pt-table-checksum.html>`_. This can be used to verify any type of backups, but before setting up replication, backup should be prepared and be able to run (this means that incremental backups should be merged to full backups, encrypted backups decrypted etc.).
+
+Setting up the replication
+============================
+
+:ref:`replication_howto` guide provides a detailed instructions on how to take the backup and set up the replication. 
+
+For checking the backup consistency you can use either the original server where the backup was taken, or another test server created by using a different backup method (such as cold backup, mysqldump or LVM snapshots) as the master server in the replication setup.
+
+Using pt-table-checksum
+=========================
+
+This tool is part of the |Percona Toolkit|. It performs an online replication consistency check by executing checksum queries on the master, which produces different results on replicas that are inconsistent with the master.
+
+After you confirmed that replication has been set up successfully, you can `install <http://www.percona.com/doc/percona-toolkit/installation.html>`_ or download *pt-table-checksum*. This example shows downloading the latest version of *pt-table-checksum*: :: 
+
+  $ wget percona.com/get/pt-table-checksum
+
+.. note:: 
+
+  In order for pt-table-checksum to work correctly ``libdbd-mysql-perl`` will need to be installed on *Debian/Ubuntu* systems or ``perl-DBD-MySQL`` on *RHEL/CentOS*. If you installed the *percona-toolkit* package from the Percona repositories package manager should install those libraries automatically.
+ 
+After this command has been run, *pt-table-checksum* will be downloaded to your current working directory.
+
+Running the *pt-table-checksum* on the master will create ``percona`` database with the ``checksums`` table which will be replicated to the slaves as well. Example of the *pt-table-checksum* will look like this: ::
+ 
+    $ ./pt-table-checksum 
+	TS ERRORS  DIFFS     ROWS  CHUNKS SKIPPED    TIME TABLE
+	04-30T11:31:50      0      0   633135       8       0   5.400 exampledb.aka_name
+    04-30T11:31:52      0      0   290859       1       0   2.692 exampledb.aka_title
+    Checksumming exampledb.user_info:  16% 02:27 remain
+    Checksumming exampledb.user_info:  34% 01:58 remain
+    Checksumming exampledb.user_info:  50% 01:29 remain
+    Checksumming exampledb.user_info:  68% 00:56 remain
+    Checksumming exampledb.user_info:  86% 00:24 remain
+    04-30T11:34:38      0      0 22187768     126       0 165.216 exampledb.user_info
+    04-30T11:38:09      0      0        0       1       0   0.033 mysql.time_zone_name
+    04-30T11:38:09      0      0        0       1       0   0.052 mysql.time_zone_transition
+    04-30T11:38:09      0      0        0       1       0   0.054 mysql.time_zone_transition_type
+    04-30T11:38:09      0      0        8       1       0   0.064 mysql.user
+
+If all the values in the ``DIFFS`` column are 0 that means that backup is consistent with the current setup.
+
+In case backup wasn't consistent  *pt-table-checksum* should spot the difference and point to the table that doesn't match. Following example shows adding new user on the backed up slave in order to simulate the inconsistent backup: ::
+
+  mysql> grant usage on exampledb.* to exampledb@localhost identified by 'thisisnewpassword';
+
+If we run the *pt-table-checksum* now difference should be spotted :: 
+
+    $ ./pt-table-checksum 
+    TS ERRORS  DIFFS     ROWS  CHUNKS SKIPPED    TIME TABLE
+    04-30T11:31:50      0      0   633135       8       0   5.400 exampledb.aka_name
+    04-30T11:31:52      0      0   290859       1       0   2.692 exampledb.aka_title
+    Checksumming exampledb.user_info:  16% 02:27 remain
+    Checksumming exampledb.user_info:  34% 01:58 remain
+    Checksumming exampledb.user_info:  50% 01:29 remain
+    Checksumming exampledb.user_info:  68% 00:56 remain
+    Checksumming exampledb.user_info:  86% 00:24 remain
+    04-30T11:34:38      0      0 22187768     126       0 165.216 exampledb.user_info
+    04-30T11:38:09      0      0        0       1       0   0.033 mysql.time_zone_name
+    04-30T11:38:09      0      0        0       1       0   0.052 mysql.time_zone_transition
+    04-30T11:38:09      0      0        0       1       0   0.054 mysql.time_zone_transition_type
+    04-30T11:38:09      1      0        8       1       0   0.064 mysql.user
+
+This output shows that slave and the replica aren't in consistent state and that the difference is in the ``mysql.user`` table.
+
+More information on different options that pt-table-checksum provides can be found in the *pt-table-checksum* `documentation <http://www.percona.com/doc/percona-toolkit/2.2/pt-table-checksum.html>`_.