Discussions related to exporting backups to tape and backing up directly to tape.
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andrewfox68
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Tape Media

Post by andrewfox68 »

Hi

We have four MSL tape libraries with a media pool for each tape library. A weekly tape would be written to with a retention period of 8 weeks. The tape is removed from the library and taken off-site. After 8 weeks the tape will be put back into the library as its retention period is up. Does a tape have to be put into the same library? If so, what are the consequences of putting a tape into a different library?

Many thanks

Andrew
Dima P.
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Re: Tape Media

Post by Dima P. »

Hi Andrew,

If all tape libraries or tape drives are assigned to the same media pool then just load the tape to any library from this list.
andrewfox68
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Re: Tape Media

Post by andrewfox68 »

Thank you for the reply.

If I have one media pool with multiple libraries, would it be the case that only the library at the top of the list would be used and the others in the list would be used for failover so would be idle if the top library is operational? Is there a way to use one media pool and all libraries to be utilised at the same time?

Thanks
Andrew
andrewfox68
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Re: Tape Media

Post by andrewfox68 »

Hi

I did some further testing on this.

A media pool created with 2 tape libraries added. A tape job was created with one backup job added. The backup job was a per-VM job with 25 VMs. The tape job ran and used all 4 drives in the first library and only used the first library.

The tape job was amended and another per-VM backup job was added. The tape job ran and used the 4 drives in the first library.

Two tape jobs were then created, both with one backup job which were per-VM and both pointed to the same media pool which has the 2 libraries added.

The first tape job ran and used all 4 drives in the first library.
The second tape job ran and detected that the first library was busy so failed over to the second library and used all 4 drives in the next library. To achieve this the option to failover when drives are busy must be selected.

So to utilise the libraries at the same time I can point to the same media pool, but require multiple tape jobs as one tape job will only utilise the first library in the list.

I hope this is the correct assumption.

This was all using v9.0 U2.

Thanks. Andrew
Dima P.
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Re: Tape Media

Post by Dima P. »

Hi Andrew,
If I have one media pool with multiple libraries, would it be the case that only the library at the top of the list would be used and the others in the list would be used for failover so would be idle if the top library is operational?
True. Libraries for the failover list are used successively. If specific failover event is checked (when all drives are busy) failover to another library will be performed automatically.
Is there a way to use one media pool and all libraries to be utilised at the same time?
Yes, check to failover when all drives are busy.
So to utilise the libraries at the same time I can point to the same media pool, but require multiple tape jobs as one tape job will only utilise the first library in the list.
Correct. One tape job can span tapes across one tape library.
This was all using v9.0 U2.
Time to upgrade to 9.5 :wink:
andrewfox68
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Re: Tape Media

Post by andrewfox68 »

Hello

One media pool was created with Tape Library 01 and Tape Library 02 added. Failover when busy was checked. The tape libraries both had 4 tape drives with 96 tapes available in each library.

Two tape jobs were created, both pointing to the same media pool.

Tape job 01 was run and began utilising the 4 tape drives in Tape Library 01, which is what I expected.

Tape job 02 was run and due to Tape Library 01 being busy it failed over to use Tape Library 02, all good so far.

Then about 10 hours in Tape job 02 stalled saying all drives were busy and it stayed stalled for 19 hours. Tape Library 01 was writing to all tape drives, but Tape Library 02 tape drives were idle.

Then after 19 hours of stalling the Tape Library 02 started being used again.

The tape jobs backup repositories which are a mix of per-vm and single chain jobs.

Any ideas on why this happened?


Andrew
Dima P.
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Re: Tape Media

Post by Dima P. »

Andrew,
Tape Library 01 was writing to all tape drives, but Tape Library 02 tape drives were idle.
What is the value for tape drive parallel processing option (I assume 4 drives)? Also, can you please check how media set creation option is configured on the media pool?
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Re: Tape Media

Post by andrewfox68 »

Hi

Parallel processing was set to 8 drives.

Create new media set for every backup session is selected.

Andrew
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Re: Tape Media

Post by Dima P. »

Thanks. Try to change the number of drives value to four since parallel processing works within one library. When all drives are busy job should failover and take another set of four drives.
andrewfox68
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Re: Tape Media

Post by andrewfox68 »

Thank you, I will try that and advise. It will probably be tested this coming weekend.

Andrew
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