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I am using Bacula and connecting to my cPanel server on a nightly basis at 2am to backup the tar.gz files that were generated the previous day at 6am by cPanel.

Note, cPanel is generating a full backup every morning and dumping it to a tar file on a per user basis.

With Bacula (my backup system that runs on a different server, backing up the cPanel tar balls) I run a full backup on the 1st of every month, and incremental on the rest of the remaining days (days 2 to 31).

Im finding that the incremental backups are still large (30-40% of the size of the full backup)... I know for sure there is not 30% of data being added in differences each night.

I guess because a small change to an input file in a group of files results in a very different tar.gz file, so there will be lots of changes from one file to the next even though the data may not have changed significantly for each file.

Would I be better off just syncing /home/* (all the user directories), and dumping the database on a per user basis to a file in the users directory (as a cron job)?

Anything else I should look out for with the above, or any other recommendations to maintain native cPanel tar.gz tarball restorations but keep incremental backups small?

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Have you tried looking in to the backups to see what is actually being backed up? That would be much more conclusive than us guessing what it could be. –  longneck Jan 19 '13 at 21:57
    
Yes its just the html files from each account in /home/. I can confirm that 3GB of data is not being added (where full backup size is 10GB). –  g18c Jan 19 '13 at 22:00
    
You say you're running a monthly full and a daily incremental. What is generating the tar file? cPanel? And then you're making a copy with Bacula? Next step would be to find out what criteria cPanel is using to decide a file qualifies for inclusion in an incremental backup. –  longneck Jan 19 '13 at 22:04
    
I have edited the original question, full backup is being generated by cPanel script every morning –  g18c Jan 19 '13 at 22:09

1 Answer 1

up vote 1 down vote accepted

You have a fundamental misunderstanding of what an incremental backup is. An incremental backup looks copies files that have changed since the last backup. THE WHOLE FILE. It does not compare file versions and copy the changes in the file.

You are running a full cPanel backup every morning. Then Bacula is taking that backup file. Since backups operate on WHOLE FILES, your entire cPanel backup is copied, not just the changes.

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cPanel has a system to generate incremental backups, perhaps you should be using that instead. It uses hardlinks, so I am not sure how Bacula would react, but if Bacula handles them intelligently it would significantly reduce your space usage. –  n8whnp Jan 24 '13 at 13:24

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