BE keeps asking for overwriteable media even they are loaded in library

[skalee]

Please excuse if this has been solved but I have spent few hours looking thru forum and haven't find a solution.

I am using BE 2012 with MSL tape library. Backups are perform to tapes. Media configuration is as follows:

- OPP is set to 3 weeks

- AP is set to "infinite - allow append"

- backup jobs are configured with "Append to media, overwrite if no appendable media is available"  option

- BE media overwrite protection level is set to: "Partial - protect only allocated media, prompt before overwriting imported media"; media overwrite options is set to: "overwrite scratch media before overwriting recyclable media contained in the target media set".

I would expect that all of above settings allow to use each media untill it is full and then protect it for 3 weeks. Looking at tapes loaded in library, I can see many tapes with given time stamp in OPP column but with much free space. Even though, when most backup jobs start, I get "Please insert overwritable media into the robotic library using the import command." Looking thru particular media, I can see that some of them contain only one backup set and other even few (more expected behaviour).

I would appreciate any comment to above situation.

Thanks in advance!

[lmosla · Accepted solution]

Hello,

change "overwrite scratch media before overwriting recyclable media contained in the target media set" to "Use Recyable media before using scratch media"

also please take a look at pkh's article 'Why is my job not appending data to my tapes?' http://www.symantec.com/connect/articles/why-my-job-not-appending-data-my-tapes

[skalee]

Hello,

Thank you for such swift response. 

I have changed the mentioned setting yesterday and it seemed that issue stopped to occur... Until today :(

Again, one of backup job hasn't appended available tapes. When I canceled it, another job started and it is appending tape...

I have read provided article and none of suggested solution seems to be suitable to this situation.

Is there anything more I can check?

Thanks in advance.

[Colin_Weaver]

One other thing to be aware of, ONLY the first tape used by a job can be appended to

As such if your currently appendable tapes only have 1/3rd of what you need available for the next backup and you have no overwritable tapes available at the time, then the job will start and choose a tape to append to as the first tape. Once it has used the free space it will try and find an overwritable tape for the second tape - so even if there is space on other tapes, if they are still under OPP they cannot be used and you will get an insert media request.

BTW whilst we can understand trying to use all the space on a tape, if you are going to use infinite append then we recommend that you periodically start a job as an Overwrite. If you always append it can create an infinitely long media family as you append from one tape to another and although an infinite family can lose tapes from the start of the sequence, if you ever lose a tape in the middle of the sequence then a DR restore where a catalog operation is needed may be difficult.

Starting a job with an overwrite starts a new media famiy and therefore means instead of one or 2 infinitely long families you have a large number of smaller families and reduce the chances of any future problems.

[skalee]

Please excuse but I am getting more confused - only one tape in destination set is filled with data but rest (at least few) have more than 50% free space...

"ONLY the first tape used by a job can be appended to" - does it mean that particular job can only append to tape where first job was written to...?

[Colin_Weaver]

Nope it means when an instance of a job starts, it can decide to overwrite a whole tape or append to existing free space on the end of a tape (depending on job start settings and media availability). If that first tape fills up before that job finishes however then the second tape that same job chooses to use can ONLY be a complete overwrite.

So valid sequeunces of tape choice for a job that fills a tape are

Overwrite Tape 1 --> Overwrite Tape 2 --> Overwrite Tape 3

OR

Append Tape 1 --> Overwrite Tape 2 --> Overwrite Tape 3

Invalid sequeneces that are not allowed

are

Append Tape 1 --> Append Tape 2 --> Append Tape 3

Overwrite Tape 1 --> Append Tape 2 --> Append tape 3

etc

as such let' s assume that you need to backup 50GB and your backup job will start as an append and the appendable tape it decides to start with only has 5GB free. The job will start and use the 5GB free as an append (probably quite quickly). It then has to find a tape to use as a second tape and that tape MUST be overwritable. If at this point in time none of the remaining tapes in your library are overwritable the job will ask for a media insert and wait. Hence you will look in your library the next day and see lots of appendable tapes but also be staring at a job that is asking for another tape.

[skalee]

Thank you for clarification, I understood the condition regarding appending to only first tape when more space is required for one job.

I am trying now to figure out how it worked in my environment. The job which I mentioned at the beginning usually is 20 GB in size. Now I can see that only one tape has less than 20 GB free space (most of them has at least 100 GB). If I understood everything correctly, it might seems that this job choosed to append the tape with insufficient space and could not complete due to lack of overwritable tapes? This isn't sound possible but this is only conclusion I can make at the moment. All subsequent job after the one I have canceled are running (and appending) as expected.

I have also checked every tape in media set to see if there is one which has only objects from today as it might indicate that it was overwritten today. I have found none...

[Colin_Weaver]

At the point in time that you cancelled the job it will have filled a tape, so for that specific job the tape of interest will now be marked as full and probably did have less than 20GB free when the job first started. You should be able to find the name of the tape in the job log of the cancelled job

[skalee]

Job's log states only: 

 - Error - Mount failed.

Operation aborted

[skalee]

Hello again,

I think I figured out what was the cause of the "canceled job" which could not append to tapes.

In backup options for this job, only differential mode had "Overwrite media" selected in "When this job begins" section... With explaination provided, it seems clear now job's behaviour.

It seems that my problems are gone now, so thank you very much for detailed explaination and most importatn - solution.

Thank you Imosla, thank you Colin.