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can i contain tape usage in a pool?

NBU 7.5.05

i learned something new today. tape pools.

if i create a tape pool and assign, let's say, 2 tape cartridges to it, can i control my backup policy to use only those tapes in that pool? if yes, should the pool run out of availables tape cartridges, will the policy wait for the pool to be replenished or will it fault?

reason is i want to be able to tell, physically, that tape labels ABC and DEF are used only for databases. because at the moment, my backups are spread out across multiple tape cartridges and as such difficult to tell which cartridge holds what data from which server.

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Accepted Solution!

There are two

There are two scenarios. 

With a scratch pool:

  • Netbackup will allocate a new tape if the pool it empty

Without a scratch pool

  • The backup will fail if no free tape exist

To be honest - the idea of telling what tapes holds which data is outdated. Netbackup will keep tract of it and can tell at any point where data are, as long as the backup is not expired. There is no reason to control that outside Netbackup. It is notorious difficult as well because Netbackup is not built with this in mind.

 

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Accepted Solution!

There are two

There are two scenarios. 

With a scratch pool:

  • Netbackup will allocate a new tape if the pool it empty

Without a scratch pool

  • The backup will fail if no free tape exist

To be honest - the idea of telling what tapes holds which data is outdated. Netbackup will keep tract of it and can tell at any point where data are, as long as the backup is not expired. There is no reason to control that outside Netbackup. It is notorious difficult as well because Netbackup is not built with this in mind.

 

View solution in original post

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how then do you keep tape

how then do you keep tape consumption to a minimum?

as it is, within two months i've consumed 140 cartridges (LTO-5). i am unable to recycle tapes because the data are spread out, like RAID-5 in hard disks. so i have to keep those sets or group of tapes together if i ever want to recover their contents in the future.
 

 

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Hi, You are probably causing

Hi, You are probably causing the problem. The more pools you create the more half used media you'll end up with. Keep your pools and retention levels to a minimum and netbackup will put all the data on the least amount of media.
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You need to tell us more

You need to tell us more about your environment -

how many media servers?

How many pools?

How many retention levels?

How many tape drives?

Media is not shared by default between media servers, so the more you have of each of the above, the more media will be used.

Have a look at this discussion about Media Sharing and Maximum Partially Full setting for a pool: 

https://www-secure.symantec.com/connect/forums/media-sharing-and-maximum-number-partially-full-media

(More info in NBU Admin Guide I)

TN: http://www.symantec.com/docs/HOWTO33855

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Good question. This is often

Good question. This is often a debate about tape management.

I personally recommend to let NetBackup handle the tapes and use a few pools as possible. Here is a comparison of methods. There is no one method for everyone.

Letting NetBackup manage the tapes.

Pros.

Since most of your tapes are in one volume pool tape usage is at its most efficient. Meaning as a tape has its images expired it can be reused for a different retention and policy.

Easier to manage since you do not have to place new tapes in each pool manually and do not have to remove a ton of tapes that have expired if the pool usage drops.

Cons.

With a large number of tapes you have to scroll through a larger list of media. 

It can be more difficult to determine which tapes contain which backups from the media list. This is easily solved by using your reporting.

Moving tapes into separate pools.

Pros.

Easier to identify which tapes should contain which data. 

Easier to locate tapes by just browsing the media pool.

Cons. 

If you stop using a volume pool, you cannot just move tapes out of the pool until ALL tape images from those tapes expire. This typically leads to a "snowball effect" of creating a new pool with other tapes and the old one gets left. After a while...you end up with a large number of pools and management becomes an issue.

If a pool has a large number of different retentions of images, that pool can start to "collect" tapes and that means less tapes for other pools. 

Generally speaking NetBackup is fantastic at managing its media and the majority of customers I work with use between 2-6 pools for backup. 

 

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Your sentence "i am unable to

Your sentence "i am unable to recycle tapes because the data are spread out"...Are you allowing multiple retention periods per tape?  That reduces the number of tapes you use in the short term, but increases overall tape usage over time because images on a tape that have expired from the NetBackup catalog will still take up space on the tape, preventing it from being reused/recycled for future backups.

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NetBackup is a data restore

NetBackup is a data restore product. Some admins forget that restore time can be as critical as backup windows. For instance. if you have ever been involved in a simulated DR scenario you will quickly realize the importance of grouping certain servers into a volume pool. You dont want to have to wait to use a tape that is already in use to become available for restoring a large server that has a short RTO. Always remember restore requirements when setting up backups.

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that is good information

that is good information there. thanks.

today, i listed all the tapes whose column "Time Assigned" is empty and found that i can recycle those tapes. but a question comes to mind.. how do you recycle? does NBU do it in the background or do i have to issue some archaic commands to recycle the tapes?

at the present, when i see the tape status as "Full" i ejected them and replace them with new tapes.

for those tapes ejected, if i reinsert them to the library will NBU start using them? as if new?

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i have no control on how NBU

i have no control on how NBU uses the tapes that's why i started searching for answers.

yes my tape usage increased because i have no control over how tapes are used. right now my best bet are the ones with expired images.
 

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if i reinsert them to the

if i reinsert them to the library will NBU start using them? as if new?

Essentially, yes.

If not already, & you actually use one, also move them into your scratch pool so that they will be available for any policy if a volume pool runs out of media.