Network Edition with Zextras for backup - redo log settings

[msutherland25]

Hi, I am just installing a ZCS Network edition and wish to use your backup solution since it is much more internet backup friendly (eg. easier to copy just the files that have changed each night). To ensure that my mass migration of users mailboxes from their old Exchange system, I have turned off the redo logs. Although you state that the Zimbra backup mechanism and Zextras backup mechanism are very different and can be used together, what you don't explain is what happens to the redo logs that Zimbra would normally created and save into the incremental backups. If you turn off the Zimbra backup then what happens to these redo logs then? Once a full scan has completed in Zextras, can the redo log be deleted? If so, how should this be done?

[Cine]

Hello msutherland25!

The SmartScan operation (the FullScan has been removed since ZeXtras Suite 1.8.17 ) does not rely on RedoLogs in any way, while the RealTime Scanner only relies on the current RedoLog file and does so autonomously by hardlinking a copy of the file: Zimbra NE automatically rotates the RedoLog file after it reaches a sized of 100mb, and archived RedoLog files can be deleted anytime - which is what Zimbra OSE does instead of archiving old files.

You can find more information about RedoLog management in this thread, while more information about the "Zimbra Network Edition + ZeXtras Suite" topic can be found on the ZeXtras Wiki.

Have a nice day,
Cine
the ZeXtras Team

[msutherland25]

Hi Cine,

I have looked at some of these articles about redo logs before but I am still not clear how to proceed in my situation!

Having imported all my users data, I am guessing that I must re-activate redo logs since they are vital for recovery if the server crashes. Can I just then leave zimbra NE backup turned off and use Zextras backup and assume that the redo logs will automatically be managed by Zimbra and will not grow out of control?

Thanks

[Cine]

Hello Martin!

Only the current RedoLog file is used to replay uncommitted transactions in case of a server crash, so archived RedoLogs can be safely removed.

If you wish to disable Zimbra NE's native backup and only use ZeXtras Backup I'd suggest to set the `zimbraRedoLogDeleteOnRollover` global property to TRUE so that RedoLogs are automatically deleted upon rotation: this is because in Zimbra NE archived and backed up RedoLogs are handled by the backup feature itself, so no backup means no old RedoLog purge.

Have a nice day,
Cine
the ZeXtras Team

[msutherland25]

Cine,

I am well used to changing to the Zimbra user and then using various command line tools to make changes but don't understand when you talk about configuration files! How to I actually change these options please?

[Cine]

Cine,

I am well used to changing to the Zimbra user and then using various command line tools to make changes but don't understand when you talk about configuration files! How to I actually change these options please?

Hello msutherland25!

The setting I mentioned is a global configuration property, so it's very easy to change it via `zmprov`:

zmprov mcf zimbraRedoLogDeleteOnRollover TRUE

As usual, run `zmprov` as the zimbra user...


Have a nice day,
Cine
the ZeXtras Team

[msutherland25]

Thank you Cine,

Just what I needed...perhaps I don't need to disable redo logs for migration if I set this option to delete redo logs on rollover then? They should get to 100Mb, get rolled over and then deleted, is that correct?

[Cine]

Thank you Cine,

Just what I needed...perhaps I don't need to disable redo logs for migration if I set this option to delete redo logs on rollover then? They should get to 100Mb, get rolled over and then deleted, is that correct?

Yes and no

It is true that by setting the "zimbraRedoLogDeleteOnRollover" property to TRUE RedoLogs are deleted when rotated, but when determining if a RedoLog file should be rotated, its age is checked aswell to prevent too many rotations in a short amount of time.

First, the size of the file is checked against the value of the "zimbraRedoLogRolloverFileSizeKB": if the file size exceeds this value, the age of the file is checked against the "zimbraRedoLogRolloverMinFileAge" property (default 60 seconds) and if the file is older thant this value it's rotated.
If the size of the RedoLog is higher than the limit but the file is not old enough, the "zimbraRedoLogRolloverHardMaxFileSizeKB" property is checked: if the file size is larger than the value of this property, it is rotated regardless of the age.


Have a nice day,
Cine
the ZeXtras Team

[msutherland25]

Hi Cine, you really know Zimbra!

I can only guess then that Zimbra is checking the last time that the file was changed then since unless redo logs are disabled during a migration, they just keep growing (ZNE)?

[Cine]

Hello msutherland25!
I've been working on Zimbra since version 5.x and I really love it, glad that sometimes my experience comes handy

Anyway yes, if redologs are not disabled during a migration they'll just keep growing...

Have a nice day,
Cine
the ZeXtras Team