Re: [Bacula-users] Recover full backup from the incrementals

Really it would come down to what files you needed to restore...

If the files you need are all in the incremental then Bacula will restore them without touching the full backup at all.

If you need to restore a full filesystem including files that will not have changed since the last full, you will possibly loose some data, depending on what has changed.

In the scenario you are talking about (w2 being damaged), you could do a full restore of w1 plus the incrementals that depended on it which would take you to the end of Saturday, and then you could do a restore of all the incrementals going forwards from there. You would miss any data changed after the Saturday incremental run after w1 but before the full w2 was run - the first incremental after w2 would have caught any changes after w2. So you would loose about a day's worth of data - depending on what type of data changes you are dealing with that may or may not be acceptable to you. The restore would be more complex than just saying "restore everything to the specified date".

Whether or not this would give you a usable restore point depends heavily on your workload - if you are dealing entirely with files that are updated in place you would be fine, the end result would be the same as if w2 wasn't damaged at all. If you are dealing with something like a busy mail server with a bunch of maildirs - a large number of files being created and deleted regularly, you would have a mess. You'd be missing a day's worth of mail plus you potentially would have 'undeleted' quite a bit of data since you would be restoring files that may have been later deleted.

So the short answer is 'it depends' - this will be true of nearly any backup software when using the approach you describe.

Bryn

On 14-10-15 03:02 AM, Sieu Truc wrote:

Hello,

I have a question about bacula's recovering mechanism.

I do an full backup every week, and the dailly incremental backups, specified in the following configuration :

Schedule {
   Name = "schedule_test"
   Run = Level=Incremental Pool=Monday Monday at 22:00
   Run = Level=Incremental Pool=Tuesday Tuesday at 22:00
   Run = Level=Incremental Pool=Wednesday Wednesday at 22:00
   Run = Level=Incremental Pool=Thursday Thursday at 22:00
   Run = Level=Incremental Pool=Friday Friday at 22:00
   Run = Level=Incremental Pool=Saturday Saturday at 22:00
     Run = Level=Full Pool=fullBK Sunday at 22:0
}

After 3 weeks, i have 3 full backup named w1,w2,w3 corresponding to each week.

If for some reasons, the backup w2 is damaged, would i lose all the incremental backup in the second week from monday to friday ?

And can i restore the backup w2 with w1 ?

Thanks,

PHAM Ngoc Truc
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