Vault using Multiple / Concurrent Drives

[Jam_Z_3]

Is it possible to Vault using more than one tape drive?

We have 4 drives, and use NetBackup 5.1MP5, but it appears only 1 drive is used for the Vaulting process which is slow and wasteful.

I've checked the Storage Unit and it is set up for Max Conccurent Drives = 4, which is correct.

I've also checked under the Vault Management section, for the Vault Profile, under the Duplication tab. In there the Destination is set to the correct Storage Unit, but strangely the Write Drives is greyed out and set to 1.

Is this correct?

At the moment I have a vaulting job which is going to take 30 hours to complete, but if it could use all 4 drives it would complete much quicker!

Any ideas or pointers?

Many thanks,
James.

[Billy_Stricklan]

It sounds like you need to set "Number of read drives:" to 2 in the Vault Profile Duplication tab under the Source section.

[Chia_Tan_Beng]

Hi James,

Billy is right. Under Duplication tab, Source section, select "Removable media and/or disk", change the "Number of read drive" to 2 and you'll see that the write drives also would change to 2.

Also bare in mind to have different storage unit for your source and destination volume pool to avoid NB attempting to assign same media for read & write during vaulting.

[Stumpr2]

James,

Do you need more suggestions?
Did someone give a helpful or correct answer?

[Jam_Z_3]

Hi, sorry for the delay I have been away etc.

I have a question about the Source Drives, you mention above setting this to 2, is this ok since the images are from only 1 source drive, our hard disk array? (all disk staged images are on this 1 disk array, with 1 logical drive letter).

If I just thought that since you are reading all the images from the same single logical disk that this is "1" disk; and that the setting for Source Drives was for vaulting images from more than 1 logical disk at the same time?

Thanks for the help,
James.

[eric_lilleness]

Hi James. It looks like your original question is answered; yes you can use more than 1 drive to do duplication. This process is hardcoded so that the number of source drive must equal the number of destination drives.

What it appears you now want to know is what will happen if you use multiple source drive on your disk STU?

To tell, the truth I don't know, but try this

(1) Configure your disk STU to allow 2 concurrent jobs

(2) Configure the duplication to use 2 source/destination drives

Test it

Issues:

We know it takes 30 hours to duplicate. We do not know how much data you are duplicating.
We do not know what type of drive your destination drive is (what is it's rated Mbytes/second?)

Also, Veritas reccommends caution when using multiple concurrent jobs with disk STU's; you may get "disk thrashing" which is excessive tarck-to-trach disk head movement.

Only the test will tell!!

[Richard_Mansell]

The first thing the vault process does is split the number of images on the disk staging area across the number of available write drives. It then does the same for any tape sourced images that need to be vaulted.

We had a problem when we first started using staging areas as the vault process was copying one less image than expected. At the time we only had one disk based image to vault but the above process was still creating a thread for the second drive. Symantec support said that it was a feature of the above process, see below:-


"During the image batching step, Vault will create 'n' empty batches for disk images when it encounters the first disk image (where 'n' is the number of read/write drives configured on the 'Duplication' tab of the vault profile). In your case, 'n' is 2. The remainder of the disk images are placed in one of these 'n' batches in a round-robin fashion. The problem observed in sid48 and sid50 was because each had only 1 disk to duplicate, so both sessions ended up with an empty disk batch:

10:47:23.701 <2> vltrun@RunDups^48: Discarding empty batch: _disk_

09:14:50.439 <2> vltrun@RunDups^50: Discarding empty batch: _disk_


So, if the number of disk images to duplicate is >= 'n', the batches will match up properly"