Question About Retention For Rotated Tapes

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Question About Retention For Rotated Tapes

Veeam Logoby pawel » Wed Jan 28, 2015 6:50 pm

Hello,

I am trying to setup 2 tape jobs for offsite storage and archival. The first job will run once to tape and be stored off-site, not an issue. However, the second job I would like to have 2 tapes which I alternate on a daily basis and which will be replaced at the end of the month.

I read the guide here:

http://helpcenter.veeam.com/backup/80/v ... _jobs.html

It says:

Protect data for (time interval). If this option is selected, archives on tapes will be preserved for the specified period. When this period is over, data will be overwritten, starting with the tape that stores the oldest archive.

This setting must accord with the retention policy specified for the backup chain that you plan to archive to tape. The retention period for archives on tape must be greater or equal to the time interval for which restore points are kept on the backup repository. In the opposite case, with every new job cycle, Veeam Backup & Replication may write the same set of files to tape, instead of adding new ones.

For example, there are 14 backup files on the backup repository that are kept for 14 days. The backup to tape job archives files once a week. The retention policy for the media pool is set to 7 days. In this case, Veeam Backup & Replication will first write 14 backup files from the backup repository to tape. After a 7-day interval, Veeam Backup & Replication will start recording the whole set of backup files from the backup repository to tape anew, overwriting backup files on tape with their copies from the backup repository.


If my backup job has 14 restore points the guide clearly states I must set the overwrite period for the tape to at least 14 days. However, how do I manage this if I have 2 tapes that will be rotated daily? Will Veeam inventory the tapes and add the required backups to it if they don't already exist on the tape? For example, if I have a nightly job that has 14 restore points and I backup to tape on Monday. Veeam will move the full backup and all incremental jobs to tape. The second day to a new tape I assume it will do the same. What happens on the third day? What files on the tape will Veeam keep and which files will it delete if I have protection set to lets say 1 month?
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Re: Question About Retention For Rotated Tapes

Veeam Logoby pawel » Wed Jan 28, 2015 8:16 pm

I should add to the above, will data only be overwritten when the tape is full or will it overwrite even if there is plenty of space on the tape?
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Re: Question About Retention For Rotated Tapes

Veeam Logoby v.Eremin » Thu Jan 29, 2015 2:49 pm

Let me ask one questions before we start talking about potential approaches. Do those tape have enough space in the aggregate to host 14 day worth of backups? Thanks.
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Re: Question About Retention For Rotated Tapes

Veeam Logoby pawel » Thu Jan 29, 2015 4:08 pm

I am using LTO-5 uncompressed so I have 1.5TB. My full backup is about 850GB and incrementals are about 30GB each (1.27GB total). So they will fit if I don't have to store the full backup more than once.
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Re: Question About Retention For Rotated Tapes

Veeam Logoby v.Eremin » Fri Jan 30, 2015 10:53 am

Oh, got it. So, is there a reason to rotate two tapes on daily basis, instead of letting backup console write to one cassette and taking another one, once capacity is reached? Seems like two tapes would be enough to host 14 day worth of backup data.

Thanks.
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Re: Question About Retention For Rotated Tapes

Veeam Logoby pawel » Fri Jan 30, 2015 3:14 pm

We need to have a tape off-site that is no more than a day old. To clarify, when I say rotated daily I mean we backup to tape, take tape off-site, insert other tape, let backup run to that tape overnight, and repeat.

I have another thread going right now where if I set the protection period Veeam will not write the same job to that tape until the protection period is over. Am I understanding that correctly? How do I get around that when rotating tapes daily?
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Re: Question About Retention For Rotated Tapes

Veeam Logoby v.Eremin » Fri Jan 30, 2015 3:33 pm

If I set the protection period Veeam will not write the same job to that tape until the protection period is over.

With the described settings your tape will be closed for additional writing for 1 day, indeed.

How do I get around that when rotating tapes daily?

What about creating mediaset on daily basis, instead of each backup session, and enabling "do not protect data" option?

Thanks.
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Re: Question About Retention For Rotated Tapes

Veeam Logoby fix-all-the-things » Fri Jan 30, 2015 5:42 pm

Are you doing full backups to tape? If so then your disk backups should be using reverse incremental. The retention settings are mostly for situations where both disk and tape are incremental backups since over-writing the wrong data on an incremental tape backup is a really bad thing. With reverse incremental to disk and full backup to tape, the only reason you would need retention on tape is so you don't accidentally over-write one, but since all of your tapes are full backups it's not quite as dangerous.
If you're swapping out the tapes daily, consider whether or not you even need to bother with retention settings. In my environment, using reverse to disk and full to tape, I found that we really didn't need to bother and it saved me a whole bunch of headaches. All of our data fits on 2 x LTO6 tapes though so rotating full backups is pretty easy. If a full tape backup would take 20 tapes then it's probably not a good idea.
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