disk staging to multiple volume pool

[rhatguy]

Hi I have NB 6.0 MP4. Our media servers currently have a couple of Tb of disk storage in one large chunk attached that we use for staging our differential backups before copying them to tape. Currently we only use our disks to stage backups that are eventually going to be written to our Onsite pool. Our full backups are written directly to tape because we want them to go into an Offsite pool due to having a different retention level. Keeping all of our fulls in the Offsite pool also helps with ejecting tapes and knowing if a tape is offsite when doing a restore.

I'm looking into running the full backups to disk as well because I get much better throughput from the local disk than from the network. The problem is that our disk staging schedule is setup to write to our Onsite pool. How are others handeling different pools? Do I have to create two DSTU's? I've thought about just creating two DSTU's in the same parent directory on the media server and setting the policies to write to the correct pool but I'm afraid I will run into problems when it comes to the high/low water marks when netbackup tries to clean the DSTU to free up space. Anyone have any suggestions on how to setup disk staging to multiple volume pools?

BTW we don't have vault.

[DavidParker]

I think you've answered your own question =)

I would just use 2 different directories and make 2 different DSSU's.

Obviously running out of space is a concern; have you done the math to see how much room you'll have/need if you add the Fulls into the mix?

[rhatguy]

Yes I have enough space to do both...but...I was hoping to be able to keep them both on the same storage unit or at least share the space somehow. In effect I want to keep all backups on disk as long as possible and only remove them when I need more space. Are you suggesting creating two directories on the same mount point? My concern with this is if I set the high water mark to say 80% on both DSTU's netbackup may be trying to find images that are candidates to expire on one DSTU even when there are no images available on that DSTU to expire (because the other DSTU was driving the space up).

[DavidParker]

Yes, I'm suggesting using 2 directories on the same mount point; that would have them sharing the space.

I don't know exactly how it will behave (off hand) when the space starts getting full, but I would assume that you can control which directory gets pruned first (especially if the pruning is done by the OS).

[rhatguy]

Pruning is normally done by netbackup.  When the disk reaches the high water mark it starts pruning old images until it gets the disk down to the low water mark.  Consider this scenario:

DiffDSTU has nothing on it
FullDSTU has 85% of space used

High water mark is set to 80% on both DSTU's

In this situation netbackup would try to prune the DiffDSTU filesystem to get it back under 80% utilization, but since there are no files it would be unable to.  At some point FullDSTU would get pruned also and at that point both DSTU's would drop under the 80% mark, but I'm wondering how netbackup is going to handle it if it thinks DiffDSTU needs to be pruned but doesn't find any images on it.

[DavidParker]

Why would it prune DiffSTU first?

[rhatguy]

It woulnd't necessarily, but it might.  Since both DSTUs are on the same partition they would both show 85% utilization even though DiffDSTU doesn't have anything on it.  Netbackup has a setting for "Check the capacity of disk storage units every x seconds", so whenever that time was reached it would attempt to prune any DSTU with a utilization above its high water mark.

[DavidParker]

Ah, I see what you mean now.

Well, it sounds like Vault-type behavior is basically what you're looking for.
On the bright side, you can do a lot of the things Vault does without acutally using/buying Vault.

You could setup a script to run daily that would 'vault' (duplicate) the oldest images and then expire them.

[Chia_Tan_Beng]

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rhatguy wrote:
It woulnd't necessarily, but it might.  Since both DSTUs are on the same partition they would both show 85% utilization even though DiffDSTU doesn't have anything on it.  Netbackup has a setting for "Check the capacity of disk storage units every x seconds", so whenever that time was reached it would attempt to prune any DSTU with a utilization above its high water mark.

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Hi rharguy,

 I believe your storage unit sits on SAN storage and you've enough space for both DSTU, why don't you slice the SAN storage into two smaller piece & mount as separate filesystem? (you'll need some space during the transition).

 Have you consider using Synthetic full backup to tape or disk? (just some thought since you've all the incrementals on disk)