Failover vs Multiple Media Pools

Everything about backing up to tape

Failover vs Multiple Media Pools

Veeam Logoby fkckbrown » Wed Jul 06, 2016 2:41 pm

We have fully moved to Veeam and have processed our first set of tapes for Offsite storage. Everything worked good with the way I have it setup, but I ran into an issue with over lapping jobs that caused it to run longer then expected. I have sense added another library to the server to increase the number of drives. My thought was to separate the jobs to the different libraries, but that requires another set of Media Pools. While looking around, I found the failover feature for tape libraries. Anyone one have any experience with this?

Both libraries have 4 drives in them (HP MSL4048) and I have two tape jobs that backup the full backups (an AM and PM group). The Media Pools are set to use 4 tape drives simultaneously and parallel processing of backup chains with a single job. Both tape jobs take a long time to completed, so the PM job starts while the AM job is still working. With the failover, will the PM jobs go to the other library? One issue I am worried about (that I had run into with the last solution) is that it backed up data on one library, but the next time it ran it was on a different library and was held up while the other library opened up so it could read data from the other tape.

Another concern I have is with Multiple Media Pools. I am guessing that this won't be an issue, but you never know. If I did a backup in one Tape Library under on Media Pool, removed the tape, inserted into the other Tape Library, will the system still recognize it correctly or will it be unknown (in a way)? In other last system, one was the central and had a copy of all the data. If I did a backup in the non central, moved it to the central, it would still know what data it had on that and everything. However if I did it the other way, the non central system didn't know what backups were on it until I did an inventory on it. Just wanted to make sure this wouldn't happen with multiple Media Pools.
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Re: Failover vs Multiple Media Pools

Veeam Logoby v.Eremin » Wed Jul 06, 2016 4:34 pm

With the failover, will the PM jobs go to the other library?

Are tape jobs pointed to two different media pools (both spanning across two libraries)? Is the order in which libraries are listed is the same in both cases (first and second media pools)? How many full backup files does a backup to tape job process?

If I did a backup in one Tape Library under on Media Pool, removed the tape, inserted into the other Tape Library, will the system still recognize it correctly or will it be unknown (in a way)?

The tapes will be recognized after tape inventory operation. (before that it will be placed in "Unrecognized" media pool).

Thanks.
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Re: Failover vs Multiple Media Pools

Veeam Logoby fkckbrown » Wed Jul 06, 2016 5:56 pm

No, I have one media pool with two tape libraries (just recently added the new one). Each library has 4 tape drives (8 in total between the two). I have two tape jobs backing up a little over 30 jobs each (an AM and PM job). Each job has 2-5 server in it (about 170 servers in total). The Media Pool is set to use 4 drives max.

Around 9:45 AM, the AM job will kick off. The next day around 12:45 AM, the PM job for the previous day is kicked off. At this time, the AM job is still running (almost done, but several jobs left to go). As soon as the PM job kicks in, it takes over all open tape drives (which basically puts the AM on hold since the drives are all being used). What I wanted to know is if I have two libraries in the Media Pool and I have this situation, will the PM job start using the 4 drives on the other library since the AM job is still finishing or is it just going to take the first 4 drives that are open (even if they are on different libraries. I don't want to have to do an inventory just to see what data is on there because I didn't put it back in the same library.

Hope this helps clear up what I am looking for.
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Re: Failover vs Multiple Media Pools

Veeam Logoby v.Eremin » Thu Jul 07, 2016 12:16 pm

As soon as the PM job kicks in, it takes over all open tape drives (which basically puts the AM on hold since the drives are all being used).

I'm not quite getting it. AM has started earlier, AM has already occupied all available drives. So, how come PM takes over all open tape drives, putting AM on hold, if none is available?

What I wanted to know is if I have two libraries in the Media Pool and I have this situation, will the PM job start using the 4 drives on the other library since the AM job is still finishing or is it just going to take the first 4 drives that are open (even if they are on different libraries.

Jobs pointed to the given media pool can only use up to 4 drives. This number can be perfectly served by single library. Thus, the switch will never happen due to the settings specified by you.

Thanks.
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Re: Failover vs Multiple Media Pools

Veeam Logoby fkckbrown » Thu Jul 07, 2016 12:43 pm

v.Eremin wrote:As soon as the PM job kicks in, it takes over all open tape drives (which basically puts the AM on hold since the drives are all being used).
I'm not quite getting it. AM has started earlier, AM has already occupied all available drives. So, how come PM takes over all open tape drives, putting AM on hold, if none is available?

What I wanted to know is if I have two libraries in the Media Pool and I have this situation, will the PM job start using the 4 drives on the other library since the AM job is still finishing or is it just going to take the first 4 drives that are open (even if they are on different libraries.
Jobs pointed to the given media pool can only use up to 4 drives. This number can be perfectly served by single library. Thus, the switch will never happen due to the settings specified by you.

Thanks.


I am guessing when the PM job starts, it waits for an open drive. When the AM tape job finishes backing up a job (the tapes back up the jobs that have a number of servers in them, I am not doing repository backup), the PM job takes that drive. It does this until it has all 4 drives, so the AM job has to wait for another drive to open for it to finish backing up another job to tape. This was before I put the second library on the server (so I only had 4 tape drives, and the media pool says it can use a max of 4 drives).

I have two jobs that are pointed at a media pool. The media pool says it can use a max of 4 drives. To my understanding, that means each job can use a max of 4 drives (8 in total between the two tape backup jobs) or is that not how it works? If that is how it works, I am just trying to confirm that all the jobs from the one tape backup will be processed by the one library and the other tape job processed by the other library or if they will grab drives from either library as they become available.
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Re: Failover vs Multiple Media Pools

Veeam Logoby v.Eremin » Thu Jul 07, 2016 12:58 pm

I am guessing when the PM job starts, it waits for an open drive. When the AM tape job finishes backing up a job (the tapes back up the jobs that have a number of servers in them, I am not doing repository backup), the PM job takes that drive. It does this until it has all 4 drives, so the AM job has to wait for another drive to open for it to finish backing up another job to tape. This was before I put the second library on the server (so I only had 4 tape drives, and the media pool says it can use a max of 4 drives).

Got it. Looks expected to me, as soon as drives becomes available it's taken by whatever job that requests it first.

The media pool says it can use a max of 4 drives. To my understanding, that means each job can use a max of 4 drives (8 in total between the two tape backup jobs) or is that not how it works?

Nope, it is not. It's media pool setting defining maximum number of drives media pool can use in parallel.

In on the words, you can point to that media pool whatever number of jobs you want to. However, all of them even if executed together won't use more than 4 drives, if 4 is defined as a maximum number.

Thanks.
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Re: Failover vs Multiple Media Pools

Veeam Logoby fkckbrown » Thu Jul 07, 2016 1:36 pm

So the only real way to effectively use both libraries so the jobs completed in the least amount of time is to have two Media Pools and one library attached to them.

The only issue is that if I put a tape in the other library (for a restore from tape), I would have to do an inventory on the tape so it can figure out what is on the tape since it is not in the same media pool as when it was written, correct?
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Re: Failover vs Multiple Media Pools

Veeam Logoby v.Eremin » Thu Jul 07, 2016 2:18 pm

So the only real way to effectively use both libraries so the jobs completed in the least amount of time is to have two Media Pools and one library attached to them.

Nope, you might as well increase the maximum number of drives a media pool can use simultaneously and tick "all tape drives are busy" check box. In that case, whenever a tape job needs more than 4 drives one library can provide, it will automatically switch to second library.

Thanks.
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