Job Backup 2 Tape - Confusing Setup Full vs. Incremental

[Poweruser]

If i setup a Job from Job to Tape its confusing because i can select two types of Tape Job: incremental or full.
If i dislike incremental (or vice versa full), i just select full only.

What will be backupped, if the repo contet is NOT full (or vice versa incremental)?
Will it create a full (incremental) file for the tape job?
Will it backup nothing or end with an error?

[Andreas Neufert]

It will create a synthesized full. Basically we create the full directly on tape reading all needed blocks from all kind of backup files in the latest backup chain.

[Poweruser]

so to be sure:

if there IS an full backup it is used, if not then it will create a synthesized full backup by taping ALL needed files of increments?
so iam sure, it will always be a standalone backup?

will it make sure, that there is no file missing?
what if i deleted sth. from the repo, rescanned and job tries to backup but cant find enoug data?
will it alert?

[Andreas Neufert]

Sure, it will read our metadata from the files first and if domething is missing the job will fail.

[Poweruser]

That sound great, but is it really great?

What if iam fiddling with the repo to save some space and delete some files and do a repo rescan.
will it destroy the intelligent backup jobs? or will veam ALWAYS and in any case notice, that it has no data and needs to start over with a full backup?
how can i proove, that an backup is really really full and not missing anything?

[Andreas Neufert]

If you trust our Synthetic full process on disk, then you can trust this as well as it works in the same way.

[Poweruser]

So we can say, that if i delete some files from repo and do a rescan, the next running job will always be correct?
the next job does not rely on sql settings or sth. it always checks if all parts are in repo?
if yes, than rescan is important? or will he rescan and check every file?

what if i have the verify backup option disabled?

[Andreas Neufert]

there is no such option on the disk backups.
Whenever a backup job misses files within the actual chain it will fail the job.

[Poweruser]

so there is a real check on every backup job for all the necessary files in forward or backward delta?
Normal software just "thinks" yes i got it backuped a day ago it must be there.

What i meant by verify is: "perform backup files health check".
Will this be necessary or will it detect missing files without this check too?

[Andreas Neufert]

Yes, health check is not needed.
We read the metadata from the backup files and if something was deleted we are not able to create the full restore point => Job will fail.

Health check read 100% of the last restore point and check if the data is intact (bit error on disc).
2 different things that has no correlation between them.

[Poweruser]

Okay fine, so you made it as i would have made it, if i would make it ;-)
Thats very good. Most other guys keep Metadata and Filedata seperated or in different files/databases.
This can be dangerous.

What i actually miss is a converter of Backups, where i can tell Veeam to change previous backuptypes at a later time.
Like: Converting forward inc. to reverse, or changing a full backup to a differential backup to save this space etc.
actually i have to keep the last big files or delete them by creating a gap.
would be nice if i could delete files over veeam while veeam repairs the delta from a -> b -> c to a->c if b (full) is to be removed.

[Dima P.]

Poweruser,

Kindly, take a look at how it works article Virtual Full Backup. All underling logic for virtual full backup on tape is covered in our Help Center article. Cheers!

[Andreas Neufert]

Thanks Dima for the confirmation.

[Poweruser]

thanks for the link. is it just me, or is the manual a bit confusing to read? (not especially this page, all pages of the manual?)