Verification after filesystem corruption

[gerdw]

Hi Forum!

I have a question concerning the verification feature of PBS:

I have several Backups of the same VM on an PBS on a store that lives on a ext4 File system.
The Filesystem got corrupted because of power failure, bad cable or so (lets assume the disk itself is ok).

After repairing the filesystem with e2fsck, some files are in lost+found which could mean something somewhere in the filesystem is missing.

If i now verify the last Backup of my VM and the verification passes OK, does it mean this backup data is OK?
As the PBS Backups are incremental, does the verification check _ALL_ the chunks that are needed to restore this particular backup or only the chunks in this incremental part?

And does the verification includes some checksum-magic or does it only check if the chunks are present?

Thanks for your thoughts about it.
Gerd

 

[dcsapak]

If i now verify the last Backup of my VM and the verification passes OK, does it mean this backup data is OK?

yes, it means that the chunk referenced in the index file are there and their content correlates with the content checksum / file crc
in case of encrypted backups only the files crc is checked, since the content cannot be read by the server, for a 'complete' verification you'd have to restore the backup from the client that has the encryption key

As the PBS Backups are incremental, does the verification check _ALL_ the chunks that are needed to restore this particular backup or only the chunks in this incremental part?

since each backup is independent and has a reference to all the chunks in it, all of them will be checked on a verify, so each backup that verifies ok should be fine

And does the verification includes some checksum-magic or does it only check if the chunks are present?

as mentioned above, there is a checksum over the content and a second (shorter) crc for the file

 

[gerdw]

Thats great! Now i know, that i can rely on a newly verified Backup.

Thanks for your fast and explaining answer.

Gerd