Xtrabackup utility fails to open the changed page bitmap file during incremental back up process

[Zytec]

Conditions:
1. An Xtradb server is configured with
innodb_track_changed_pages = 1,
datadir and innodb_data_home_dir are different to each other:
innodb_data_home_dir=/dbdata/db01/mysql/data/ibdata
datadir=/dbdata/db01/mysql/data/mysqldata
The Xtradb server successfully creates a series of ib_modified_log_%.xdb files in the innodb_data_home_dir directory.

2 .The prior execution of a full backup completed successfully and its target files are all in place.
 Xtrabackup is now being executed with the following command-line parameters:
/usr/bin/xtrabackup --defaults-file=my.cnf --compress --compress-threads=2 --open-files-limit=25000 --backup --data-dir=/dbdata/db01/mysql/data/mysqldata --incremental-basedir=/backup/db01/full --target-dir=/backup/db01/incremental

Upon displaying a row of execution parameters xtrabackup displays a warning indicating it
could not access the changed bitmap file:

/usr/bin/xtrabackup version 2.2.3 based on MySQL server 5.6.17 Linux (x86_64) (revision id: )
incremental backup from 165547922197 is enabled.
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /dbdata/db01/mysql/data/mysqldata
xtrabackup: open files limit requested 25000, set to 25000
xtrabackup: using the following InnoDB configuration:
xtrabackup: innodb_data_home_dir = /dbdata/db01/mysql/data/ibdata
xtrabackup: innodb_data_file_path = ibdata1:128M:autoextend
xtrabackup: innodb_log_group_home_dir = /dbdata/db01/mysql/data/iblog
xtrabackup: innodb_log_files_in_group = 3
xtrabackup: innodb_log_file_size = 67108864
xtrabackup: using O_DIRECT
>> log scanned up to (169631977007)
InnoDB: Warning: error opening the changed page bitmap '/dbdata/db01/mysql/data/ibdataib_modified_log_1_0.xdb'
xtrabackup: using the full scan for incremental backup
<cut>

The innodb_data_home_dir value is right but xtrabackup forgets to put a '/' between the innodb home dir and a bitmap file name thus trying to open a wrong file name in a wrong directory.

[Nilnandan Joshi (nilnandan-joshi)]

xtrabackup version 2.2.3 based on MySQL server 5.6.17 Linux (x86_64) (revision id: )
incremental backup from 1625997 is enabled.
xtrabackup: uses posix_fadvise().
xtrabackup: cd to /var/lib/mysql
xtrabackup: open files limit requested 65535, set to 65535
xtrabackup: using the following InnoDB configuration:
xtrabackup: innodb_data_home_dir = /var/lib/mysql/ibdata
xtrabackup: innodb_data_file_path = ibdata1:10M:autoextend
xtrabackup: innodb_log_group_home_dir = ./
xtrabackup: innodb_log_files_in_group = 2
xtrabackup: innodb_log_file_size = 50331648
>> log scanned up to (27967511)
InnoDB: Warning: error opening the changed page bitmap '/var/lib/mysql/ibdataib_modified_log_2_1625987.xdb'
xtrabackup: using the full scan for incremental backup

It seems, path should be /var/lib/mysql/ibdata/ib_modified_log_2_1625987.xdb

[Alexey Kopytov (akopytov)]

A similar issue exists in Percona Server. Even though files are created and written, the corresponding INFORMATION_SCHEMA tables is unavailable with a non-default innodb_data_home_dir. Reported as bug #1364315.

The workaround is to make sure innodb_data_home_dir has a trailing slash, e.g. /usr/local/mysql/ibdata/

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXB-923