[Documentation] Caveats with --no-lock should be clearly mentioned

Bug #1075444 reported by Raghavendra D Prabhu on 2012-11-06
10
This bug affects 2 people
Affects Status Importance Assigned to Milestone
Percona XtraBackup moved to https://jira.percona.com/projects/PXB
Fix Released
Medium
Hrvoje Matijakovic

Bug Description

Currently it states:

"""
--no-lock

    Use this option to disable table lock with FLUSH TABLES WITH READ LOCK. Use it only if ALL your tables are InnoDB and you DO NOT CARE about the binary log position of the backup. If you are considering to use --no-lock because your backups are failing to acquire the lock, this could be because of incoming replication events preventing the lock from succeeding. Please try using --safe-slave-backup to momentarily stop the replication slave thread, this may help the backup to succeed and you then don’t need to resort to using --no-lock.

"""

I think the condition of no DDL being executed should also be added, running a DDL otherwise during --no-lock + innobackupex can lead to inconsistencies. Reasons for that can also be added to explain why (DDL is non-transactional, hence ibd file creation not recorded in redo logs etc)

Tags: doc Edit Tag help

Related branches

Alexey Kopytov (akopytov) wrote :

Not only .ibd file creation is not redo-logged, but also .frm files creation/removal/modifications. I.e. we should make it clear that --no-lock can only be used if:

1. No DDL to any tables occurs during a backup.
2. No updates to any tables other than InnoDB occur during a backup (this include updates to system MyISAM tables in the 'mysql' database).

Changed in percona-xtrabackup:
importance: Undecided → Medium
Changed in percona-xtrabackup:
status: New → In Progress
Changed in percona-xtrabackup:
status: In Progress → Fix Committed
Stewart Smith (stewart) on 2013-01-22
Changed in percona-xtrabackup:
status: Fix Committed → Fix Released

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXB-605

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