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pkh
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Question: Why is my job not appending data to my tapes?

 
Answer:  There are a couple of reasons why jobs do not append data to tapes.
 
1) The job is set to overwrite.
 
To append data to tapes, the job must be set to either of the two append option.  See the figure below
 
 
 
 
2) The job will only append to the first tape.
 
A job can only append to the first tape that it writes to.  When that tape is full, it will require an overwriteable tape.  It cannot append to the second or subsequent tapes.  This is by design and there is no way to change this behaviour.
 
3) The append period is too short.
 
The append period is calculated from the START of the first job that over-writes the tape.  The append period is not extended after this.  Suppose the append period is set to 5 hours and the first job that over-writes the tape takes 6 hours to complete.  By the time the job completes, the tape is no longer appendable.
 
 
By job overlap, I mean; while the first job is running, the second job starts.
 
When a job is running, the tape is marked as unappendable because the end-of-file marker is not written.  If a job starts while the first job is running, then it will not be able to find an appendable media.  It will then switch to overwrite mode, if the job property is set to "Append, overwrite if if no appendable media is available", or it will fail if it is set to "Append, terminate job if no appendable media is available".  For the first append option even when the job finally finishes waiting and start, it will use an overwriteable media and will not switch back to the append mode.
 
The only solution for this situation is to schedule your jobs in such a way that there is no overlap.
 
 
 
Question: What about disk media?
 
Answer:  The above is also applicable to disk media.  However, for disk media, there is no advantage to appending to a media.  For tape, you append data to them to maximise the use of the tape capacity.  For disk, you can use as much or as little disk space as you require, provided you have not set the B2D folder property to allocate the maximum size for the .bkf files.  By appending to a disk media, you would extend the overwrite protection period of that media and thus preventing it from being recycled earlier.  For example, your first job creates a .bkf file and the overwrite protection period is 3 days.  On the 4th day, this .bkf can be overwritten and the disk space occupied by it is re-used.  However, if there is a second job the next day which appends to this file, then the .bkf will only be overwriteable on the 5th day.  Thus the space occupied by the data from the first job is locked up for another day before it can be overwritten.
 
This is why you should always set your jobs to Overwrite if you are writing to disk media.
Comments
Ken_Putnam
Level 6

#5    Your 2nd (3rd, 4th,  ...) job does not specify the media set that the tape already belongs to

medikal
Level 4

i have be 2012 what i need to see there??

Tsuki_Akurei
Level 3

Number 4 of this article basically solved 3 months of overwrtire / append headaches for me. I could not understand why my backups failed continuously even if theoretically everything was fine.

Thanks a lot!

Rajum
Level 2

Hello,

Please see the technotes as additional information:

An explanation of the "Overwrite Protection Period" and the "Append Period"

http://support.veritas.com/docs/237374

The basics of Advanced Device and Media Management for Backup Exec for Windows Servers

http://support.veritas.com/docs/192265


Thanks

SjorsH
Not applicable

I had a hard time getting my backup to append to a tape. It was still in the robotic library but marked "Export Pending" (seen in tape details). Exporting the tape and importing it back in did the trick.

sdo
Moderator
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Partner    VIP    Certified

Hi - does item 4):

"When a job is running, the tape is marked as unappendable because the end-of-file marker is not written. If a job starts while the first job is running, then it will not be able to find an appendable media. It will then switch to overwrite mode, if the job property is set to "Append, overwrite if if no appendable media is available", or it will fail if it is set to "Append, terminate job if no appendable media is available". For the first append option even when the job finally finishes waiting and start, it will use an overwriteable media and will not switch back to the append mode."

...also apply to duplication jobs ?

In my environment we have B2D2T, all backups are saved to eight disk storage areas, each with max two jobs - so I can 16 backups running - thus there can be many backups completing, all of which have an immediate duplication stage - but I only have two target tape drives for duplications - which leads on to many duplications waiting (which I'm ok with).

Please could someone re-explain point 4) above - but in terms of duplication jobs?

Thanks.

Colin_Weaver
Moderator
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Employee Accredited Certified

I know I m answers a comment from a few months ago, however as it was not answered and for benefit of others:

The tape allocation (decision making for using append vs Overwrite) is the same for both backup and duplication jobs

Also in all cases once backup Exec switches a job from looking for an Appendable Tape to looking for an Overwriteable Tape, the job will not swicth back tp looking for append.

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Last update:
‎12-12-2011 10:32 PM
Updated by:
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