SLP duplication, how to send more than one image to one tape.

[famari]

Folks, I´ve configured a SLP to duplicate data that are in disk to tape. But checking the NBU, I saw 10 SLP sessions running at the same time, and each one send only one image to tape. 

Is there any way to configure it sending for example 10 images to a single tape, using only one SLP session?

Thanks

[davidmoline]

There are a couple of ways to alter the current behaviour. 

Firsty look at the tuneable SLP parameters for the master server - you could try increasing the maximum size per duplication (MAX_GB_SIZE_PER_DUPLICATION_JOB) so that more duplications are combined into one SLP job (if each duplication job is large itself, this may not help much). I'd suggest setting this parameter to something close to the size of the tape media. Also check that the TAPE_RESOURCE_MULTIPLIER is not set too high (the default value of 2 is usually good).

The other way would be to adjust the storage unit you choose to perform the duplications and reduce the maximum concurrency - here rather than changing the current one (which would also affect backup operations) create a specific STU for duplications which targets the same tape drives/robot, but with reduces concurrency. 

Finally I would be recommending droppng the concurrency to one, as duplication operations are single threaded, so run one after the other. If you have a lot of jobs to duplicate restricting the number of simultaneous jobs may cause your duplications to queue and not finish in time.

[sdo]

@famari  If you are thinking about "multi-plexing" then the facts are:

1) NetBackup never writes multi-plexed backups to fixed disk (Basic Disk, Advanced Disk, MSDP, other vendor disk storage units)

2) NetBackup can only ever write multi-plexed backups (if configured) to physical tape, or to virtual tape (VTL).

3) NetBackup cannot create a new multi-plex set when duplicating (either manually or scripted or via SLP) from disk (any type) to tape (physical or virtual).

4) NetBackup can persist multi-plexing, i.e. if duplicating from tape to tape (e.g. from physical or virtual either side either way) - if configured correctly.