mainstoreBackup - Support: sr #108965, Integrity of database system...


sr #108965: Integrity of database system tablespace when using blocked files

Submitter:  None
Submitted:  Sat 06 Feb 2016 07:19:08 PM UTC
Category:  None Priority:  5 - Normal
Severity:  3 - Normal Status:  None
Privacy:  Public Assigned to:  None
Originator Email:  -email is unavailable- Open/Closed:  Open
Operating System:  GNU/Linux
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Sat 13 Feb 2016 08:07:25 AM UTC, comment #3: 

Hello Heinz-Josef,

thanks for the clarification. That's why I decided to use mysqldump which does a consistent backup of the database even in online mode (by setting the right parameters). Everything else works fine after I have excluded some more directories (used by postfix). The log doesn't show any error messages now. I haven't tested the restore features yet.

Great work!


Fri 12 Feb 2016 02:04:30 PM UTC, comment #2: 


if you want to backup a blocked file (or any other file) which is changed during the backup, then you have to create something consistent (if you want a consistent backup of that file). This can be done with a snapshot (from the affected program itself or created from the storage layer).
Storebackup doesn't care about the data it's storing.

Heinz-Josef Claes <hjclaes>
Group administrator
Thu 11 Feb 2016 06:23:36 AM UTC, comment #1: 


after examining the log files for a couple of days I have drawn the following conclusions:

1) Using blocked files is useless for database system tablespaces because changes to the database affect (almost) all blocks so that a full backup is done each day.

2) I decided to exclude the whole data directory (var/lib/mysql) from storeBackup and to stick with mysqldump (via automysqlbackup) for backing up the database system because it allows online backups ('hot' backups). Of course, restoring the entire system is more time-consuming in this scenario.

Sat 06 Feb 2016 07:19:08 PM UTC, original submission:  


I have just started using storeBackup on a 24/7 Ubuntu sytem (14.04 LTS) which is used mainly as a web and database server. I have decided to use blocked files for the MySQL system tablespace (ibdata1) which has a size of about 14 Gb at the moment (and is growing rapidly).

Of course, the log file contains a warning message "<//var/lib/mysql/ibdata1> changed during backup" (the same applies to some larger log files). I wonder if (and how) storeBackup can ensure the integrity of the original file and the blocked files, respectively, when the original file changes during backup. Would it be better not to use blocked files for the tablespace?

Of course, I am aware of the fact that it would be better to backup the database in offline mode, but it continuously logs data from a home automation system, so putting the database in offline mode would cause a (minor) loss of data and would not be ideal.



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