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Append Date Not Applying

Created: 11 Nov 2013 • Updated: 18 Nov 2013 | 6 comments
This issue has been solved. See solution.

Hi All

Small environment, single tape unit running a full backup of servers Fri and differential Sun-Thur.  Everything should fit on 1 tape (LTO 4 800/ 1600).  Have 5 tapes that we rotate.  Every Fri we put the weekly tape in and fast erase it.

The overwrite protect is set to 4 weeks and the append is set to infinite.  If I check the append until date it never says infinite, it is always set to the Thur of the week. the result is our final differential backup fails with no available media.  We have tried running incremental instead of differential but get the same error.

Just wondering if it's the erasing of the tape that is doing this, i.e. not setting the correct appendable until date?  Even though the initial full backup backs up fine on the Fri and the overwrite protect date is correct i.e. 4 weeks from the initial backup.

Appreciate any help, this is production environment.  Server 2008 R2. BUPEXEC 2012 (14.0 Rev 1798)

Thanks
gR

Operating Systems:

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Colin Weaver's picture

 

If you get your overwrite protection and append periods correct then you should never have to erase or manually move tapes to scratch as an overwrite will do it for you.

 

Also Append Infinite is a generic setting that is not really appropriate for stand alone tape drives because when an append jobs fills that last remaining space on the tape it needs a completely different tape to finish the rest of the job. Two key facts you may not be aware of

1) You cannot append to the second tape in a job when the first tape used fills up mid job - this switches to an overwrite when asking for the second tape.

2) When you overwrite a tape it is the whole tape, not just the old backup set at the start of the tape. This operation is why we do not let you overwrite the same tape that an append jiob inistuiallt starts on when it fills as if we allowd it then the end of the backup woruld overwritye the beginning resulting in an invalid data set.

 

Recommendeations (do one or all of these)

 

Once a week (so some other appropriate period) start your job as an overwrite.

Know how many backups you can get on a tape so that you have not completely filled the tape and base you append period on the time to achieve thsi number of backups

Stop using Infinite append

Consider a library so that the jobs have a second tape to choose from when the first fills up.

 

EDIT: I am not sure why your append period seems to report an odd timing, although have you checked the year as in reality I think an infinite appens sets the year date as a long time in the future (as a way of faking infinite)

 

gerryR--DigitalSkills--'s picture

Hi

Thanks for the reply and info.  I had initially set the Overwrite to 4 weeks and the append to 14 days but it I was getting the same problem.  No matter what I set append to it seems to revert to 6 days and given we backup each night and some backups run past midnight we always miss a few servers on the last date.

A full week of backups takes over half a tape, the reason I do a manual erase on the Fri's full backup is there's the potential the tape will run out and we don't want to span over two tapes, we're happy with having 5 weeks of backups.  Put a tape in Fri, replace and erase next Fri is about as hassle free as I can get with the system.

Does manually erasing the tape have the same effect as the tape being overwritten?  i.e. should that be resetting the necessary info for the append date to kick in?  I'll try adding the tape to scratch on Fri to see if that does the job but any more info would be appreciated.  PS- No chance of getting a library.

Thanks
gR

Colin Weaver's picture

The append date is based in an Overwrite operation. What a manual erase does (I think) is put the media in the scratch set. Which then becomes an overwrite at the time a future job tries to use it. As such the erase does have an effect on when an append can take place but only because it allows the tape to be overwritten. In reality a correct Overwrite Protection date would have the same effect without needing the erase.

 

Overwrite to 4 week and append to 14 days more or less means that if you overwrite the tape on Feb 1, as long as all your appends for work the next 14 days then the tape will actually be overwritable on March 15th (allowing for the job length of the backup job on 14th day of append)

We protect the last piece of data on the tape based on date and time of end of last job or when tape fills up whichever comes first.

 

BTW with regards your dates/times, Are you erasing the tape AND manually moving it to a media set, as manual moves can mess things up, always let BE do the moves for you (uness you want to infinitely protect a tape that is not under infinite protection currently.)

gerryR--DigitalSkills--'s picture

Will Overwrite always overwrite the tape or will it only overwrit if there is not enough space?  If it's the former then I can try setting an Overwrite to 2 weeks and append to 8 days.  That would save me having to erase but I have my suspicions that I will only get 6 days of append as anything I've tried has reverted to 6 day append.

If it's the latter then it's no good as I do not want to span over two tapes.

On a Fri afternoon, I put the tape in, run inventory and then a fast erase.  I don't do anything else.  Should I be?

Thanks for the help
gR

Colin Weaver's picture

OK if you truly are getting 6 days append from a tape that has just been overwritten by a job and you are setting 14 day append then you need to log a formal support case as our internal test systems give 14 days in that situation and not 6

 

However please test by using a tape you don't mind overwriting and create a one off job that is set to  overwrite at start of job to the tape but using the same media set that you have been using. After you have run the test backup check the append until setting for the tape and if it shows 14 days then something you have done in your normal cycle of media in your normal job is causing the problem. If it shows 6 oand the job log clearly states it was overwritten then something is going wrong in BE itself.

 

 

SOLUTION
gerryR--DigitalSkills--'s picture

Thanks for the help, 

I think I've found the issue.  I was setting the 2 week overwrite, 14 day append period within the backup jobs themselves but the media set the tapes were members of had the 6 day append period which seemed to superseding anything I set in the job settings. 

The media set is something I hadn't looked at, I'm assuming it was created when the initial job was set up?

Thanks again for the help

gR