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Overwrite Protection and multiple jobs to single tape

G'day All.

We have an implementation of BE2010 utilising a single LTO3 drive for daily incremental, and weekly and monthly full backups. We are currently using multiple jobs with different selection lists to capture different data areas for our backups. We have three different media sets for each group of jobs with different overwrite protection periods for each. The daily media set has an overwrite period of 6 Days, the weekly 4 weeks and the monthly 1 year.

I'm having some trouble understanding exactly how the overwrite protection periods work. There are some instances where the daily jobs will run one after another, happily writing to the same tape and other instances where after a job the media becomes overwrite protected and subsequent daily jobs fail.

Is anyone able to shed some light on why this would be occuring?

Also, if someone is able to clarify whether overwrite protection protects an entire tape, or simply the data from a job while allowing appends. I suspect it's the former, but if that's the case i don't understand how multiple jobs can ever run to a single tape with overwrite protection set.

I appreciate any assistance given.

 

3 Replies

Re: Overwrite Protection and multiple jobs to single tape

Read this for a better understanding of OPP

http://www.veritas.com/docs/000032654

 

The entire tape is protected.

Re: Overwrite Protection and multiple jobs to single tape


@obi_jay wrote:
Also, if someone is able to clarify whether overwrite protection protects an entire tape, or simply the data from a job while allowing appends. I suspect it's the former, but if that's the case i don't understand how multiple jobs can ever run to a single tape with overwrite protection set.

 


Overwrite protection protects the entire tape.  Multiple jobs can run when the other jobs run in "append", not "overwrite" mode.  Therefor they are "adding"/appending information to the end of the tape.

Re: Overwrite Protection and multiple jobs to single tape

Hi OBJ,

I will try my best to give you a better understanding regarding the OPP for tapes.

Lets take your environment.

Daily Media set: OPP: 6 Days.

Lets say the tape capacity is 2 TB and your backups (Multiple or a single job) data size is 1.8 TB(Approx)

Tape follows MEdia set which is comprised of APP and OPP.

So, once the job of 1.5 TB have been kicked off to the tape, the job will complete after writing 1.5 TB of data and the moment once the backup completes, OPP starts.

I conclude, OPP is for the data which is inside the tape.

After wrting the backup to the tape, the 1.5 data will be protected for 6 days(OPP) and its upto you to choose a valid APP for filling up the remaining 0.5 TB in the tape.

Please revert for further queries.

Thanks,

Selva.