NetBackup multiplexing SLP to tape

[BlobZ]

Hi everyone,

Can you confirm or deny that it is valid/possible to create secondary copies of backups from a dedupe, standard or advanced disk pool to tape.

We are finding that as we grow the time taken to rehydrate a deduped backup is so slow that the tape drives are running slow and the secondary copies are not happening qucik enough.

Thanks.

bob

[Marianne · Accepted solution]

Not sure what your 1st statement/question is all about as duplication from any kind of disk backup is common practice. It sounds like you need assistance with troubleshooting and/or performance tuning of duplication of dedupe data to disk, right? Information about your environment will help. Are default SLP parameters used or customized? Duplication across the network or locally on the media server? Media server hardware config? Memory/cpu? Number of hba's and placement? Disk and tape on different hba's? Any kind of tuning done on the media server as per the Performance Tuning Guide?

[BlobZ]

Maybe I should clarify.

All our clients backup across the network to our NetBcakup servers and the backup images go straight to some form of disk pool.

Critical backups then have a secondary copy of the image pushed out to tape via SLP.

We are seeing one to one relationship between the backup job and the tape so the tapes get used for too long and we can't clear the secondary copies before they start again.

I just want to know if it is possible to multiplex or multistream multiple SLP driven image copies to tape.

Bob 

[Nicolai]

Never heard of multiplexing SLP's.

My personal opinion, you should try to resolve the performance of the MSDP pool.

• Upgrade to 7.6.1.1 - big performnce boost +30% on same hardware.
• Ensure disk are up to the job - multiple spindles/premium disks (SAS/FC - no SATA).
• don't overload with too many SLP at a time

[Marianne]

You may want to download the SLP Best Practice Guide:  http://www.symantec.com/docs/TECH208536  
(The pdf is under the 'attachments' link.)

Go through topics such as:
Use duplication job priority to group SLPs 
Large duplication jobs are more efficient
Considerations for environments with very large images and many very small images
Considerations when duplicating multiple stream application backups 

etc...

[Marianne]

A similar current discussion:

 Very slow throughput in SLP duplicatkion jobs 

[ontherocks]

You can not start the multiplexing at duplication state in SLP.

Multiplexing needs to enabled at the time of backup(Tape only) and you will select option to preserve the multiplex or not at the time of duplication.. you can not start the multiplex at the stage of duplication.

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If you would like to start the mulitple images in single Duplication job you can use the with the help of  SLP tuning parameters.

MIN_GB_SIZE_PER_DUPLICATION_JOB 8 / Default value: 8 GB
Adjusting this value, indicated in gigabytes, affects the number and size of duplication jobs. If the MIN_GB_SIZE_PER_DUPLICATION_JOB setting is small, more duplication jobs are created. If it is large, fewer, larger duplication jobs are created.

MAX_GB_SIZE_PER_DUPLICATION_JOB 25 / Default value: 25 GB
This entry controls the maximum size of a duplication job. (When a single image is larger than the maximum size, that one image will be put into its own duplication job.)

see the below tech note.