Unable To Overwrite Tapes

[djoaquin]

Hell All,

I am new to Netbackup.  We have moved over from Arcserve.  Here is our setup:

-NBU 6.5 on Linux serve.

-This server is the master server and media server.

-I backup 4 client servers to one attached LTO4 drive.  It is a stand alone drive.

-The 4 policies all run at the same time and are multiplexed to the drive.

-All policies are set to 1 Week retention

-I remove the tape nightly and then put in the next days tape. The tapes re-used once a week.

-All of these tapes are part of the same volume pool.

The problem I am having is the jobs seem to be appending and not overwriting. After a few backups the tape becomes full.  I know it should not be because I am only backing up about 220GB and that drive does 800GB native/1.6TB compressed.

Since the policy is set to 1 week retention, shouldn't it be overwritten when I put in that tape again on the same day the following week?  I have checked the catalog and only see the previous nights backups listed.  So it looks to me like the previous weeks jobs were expired.

Do I have something wrong in my setup?  Have I missed the option to say overwrite the tape?

I would be happy to give more detail on the jobs if you need it.

Thanks for the help,

Daniel Joaquin

[djoaquin]

Ok.  I have a theory.  Can someone tell me if it could be right?

I have a 1 week retention on my jobs and am reusing that tape a week later.  Could it be that because the job takes several hours to complete, the job does not truely expire until that time the following week?  So when I start the job, it has not been a full week and therefore it gets appended instead of over written?  If that is the case, then each week I will get an append until the tape is full.

Thanks for any help.

Daniel

[Patrick_Whelan_]

Your theory is correct. The tape does not expire until the last image on the tape expires which is, in your case, one week from the end of the backup. If, as you say, the tapes are being appended to, they will not expire until the last image expires. So you could have 100 expired images, and one unexpired images, and if the tape is full, it will not be used until that last image has expired.

[djoaquin]

That makes sense to me but then how would you do a day, week, month rotation?  I understand that to be a common backup rotation.  If it is timed from the end of the backup, then you would either have to start the backup later each week or set the retention to 6 days.  In the software though, the shortest retention time I have is one week.

Can anyone tell me how to re-use a tape (such as a Monday tape) weekly? It seems like it should be easy but I think I am still getting adjusted to the Netbackup way of thinking.

Thanks,

Daniel

[cmumma]

The tapes get expired and returned to the scratch pool all at once each night.  It doesn't happen at the exact time the image is set to expire, it's more like a batch job.  So, the tape you used on Thursday with a 1 week retention will not get returned to scratch until Thursday night of the following week.  You could manually expire the images and the tape before you run backups, but it would probably be easier to just get two weeks worth of tapes.

[Omar_Villa]

regarding the size of usage are this tapes LTO4 or LTO2? you can have an LTO4 who can read and write to any other LTO tape, but the tape capacity cannot be changed even if you are using an LTO4 drives with LTO2 tapes.

regards.

[djoaquin]

I am using LTO4 tapes.  Size is nto the issue.  The issue is the expiration because the jobs keep getting appended.

I see your point about using two week rotations.  Seems like such a waste though.  So is the answer that Netbackup will not allow day, week, month rotations unless you manually expire the media?

Is there a way to reduce the retention time to less then 1 week?

Daniel

[djoaquin · Accepted solution]

Bingo!  I found a way to do it.

Under the Master Server properties there are Retention Period settings.  I changed Retention Level 0 to 6 days instead of 1 week.  I belive this should cause the backups to expire the day before they are used again.

I will let everyone know if this works next week after they run though again.

Daniel

[Darren_Dunham]

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@djoaquin wrote:

That makes sense to me but then how would you do a day, week, month rotation?  I understand that to be a common backup rotation.

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It is a common rotation, but usually it exists only to simplify the handling of tapes.  With a product like Netbackup where the catalog can track every single image easily (even across multiple tapes), you usually don't need such a scheme.  Instead you can declare exactly how long you want your data to last, then you purchase enough media to accomodate that request.

Now you may need a few more tapes to track things this way, but as your environment grows, it's the only way to stay sane.  You do *not* want to be tracking things like a "monday tape" when you're dealing with hundreds of backups.

If you're familiar with that scheme, it is possible to force NetBackup to do it, but you're not really doing things the easy way if you do so.   

--

Darren 

[djoaquin]

Well that fixed my issue.  Changing the retention time to 6 days allowed the backups to be overwritten on the 7th day.

Thanks for the help,

Daniel Joaquin

[MariusD]

One questions??????

I use netbackup 6.5.2. I can choose just 1 Week, 2 Weeks, ......or 1Year Retention. How did you choose 6 days??????????Or 11 Months???????

Thanks a lot,

Marius D.

[Andy_Welburn]

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@MariusD wrote:

One questions??????

I use netbackup 6.5.2. I can choose just 1 Week, 2 Weeks, ......or 1Year Retention. How did you choose 6 days??????????Or 11 Months???????

Thanks a lot,

Marius D.

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On Admin Console GUI. Within Host Properties/Master Servers select your Master server & open "Retention Periods". You are presented with your current retention periods in tabular form e.g. RL=0, Period=1 week etc. Choose one from the list that you aren't using (for us that would be levels 10-24 which are currently set to infinity), change the units from the drop down list to what you need (hours/days etc etc) & then the value.

It is NOT recommended you change any you are already using (schedule count column >0) unless you are absolutely sure of the impact that this would have on your tape usage.

[MariusD]

Thank you for your reply. Now i´m saved :))).

O good day,

Marius D.