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manmountain's avatar
manmountain
Level 5
12 years ago

Multi Streaming Data and Multiplexing to disk

 

Hi, I am trying to figure out what value I should assign for parameter 'Maximum Concurrent Jobs' when configuring storage unit. How can I come up with a value for 'Maximum Concurrent Jobs' that will best optimise performing backups for my setup?
 
I am storing backups onto a disk storage unit as part of disk stage 1. The disk storage unit is a ZFS config and consists of a VNX connected over fibre to netbackup media server.
 
My understanding is that multiplexing is used for backing up hosts to tape drive. So if I firstly backup to disk first what value should 'Media Multiplexing' be set to in the Atributes tab when setting up schedule. 
 
Also if I use multi streamed backups to disk and then relocate images to tape later will this have an affect on restores? Do I have have to perform a Multi-streamed restore? 
7.1.x and Earlier
Backing Up
Backup and Recovery
Configuring
NetBackup
Solaris
  • Mark_Solutions's avatar
    Mark_Solutions
    12 years ago

    As Marianne says i think the original question has been answered but let me clarify and cover the drives too ...

    When writing to disk the maximum number of streams is governed by the storage unit itself only so the number you set here is dependant on the capability of your backup server (disk speed, memory and network)

    The multiplex value in a schedule relates to tape backups only.

    When backups are duplicated from disk to tape they run one image at a time and so do not multiplex onto the tape - as a result you do not need to set a multiplex level for tape if using disk staging

    Your output shows two tape drives - the first shows UP but i do not see a status for the other one. If it is also UP and does not have a tape stuck in it or anything similar then as long as you tape storage unit is set to have 2 concurrent drives in it both should be used

    Hope all of this helps

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  • Nicolai's avatar
    Nicolai
    Moderator
    12 years ago

    Backup direct to disk will always be non-multiplexed.

    Relocation from disk to tape should have a multiplexing of 1. Remember you can have more than one storage unit for a set of tape drive (use one for duplication and one for backup direct to tape).

    You should also limit the amount of concurrent IO to the disk storage unit. Try a value of 20 concurrent IO and tune from there.

    Multi stream backup to disk will be single stream on tape. This is a issue Symantec know and is working on to resolve.

    Best Regards

    Nicolai

  • manmountain's avatar
    manmountain
    Level 5
    12 years ago

    Ok thanks for the info Nicolai.

    Multi stream backup to disk will be single stream on tape. This is a issue Symantec know and is working on to resolve.

    Are backups then queued when being backed up to tape?

    If I have 2 tape drives is it possible to create 1 storage unit group containing both tape drives?

  • Nicolai's avatar
    Nicolai
    Moderator
    12 years ago

    Let me clarify :-D

    If you write 5 stream from e.g. a database backup to disk, all stream will write concurrent. But when the data is staged to tape and you need to restore the data from tape it will be restores as if it was a single stream of data. Netbackup does not have the logic to spread multiple stream to disk to multiple tape drives.

    Yes -  two tape drive from two storage unit can be put in a storage unit group.

  • manmountain's avatar
    manmountain
    Level 5
    12 years ago

    Ok thanks Nicolai. Would that be the recommended setup to make the best use of both drives in a tape library unit?

  • Nicolai's avatar
    Nicolai
    Moderator
    12 years ago

    Yes I would think so - unless there are specific requirements. You don't even need to put the drives in a storage unit group. A single storage unit can point to two drives.

  • manmountain's avatar
    manmountain
    Level 5
    12 years ago

    I have selected the tape robot when setting up storage unit but it seems that only one of the drives is selected anytime when performing a backup. 

    This drive is only ever used HP.ULTRIUM5-SCSI.000 even though there are 2 drives available. 

     

     

    Id  DriveName           Type   Residence
          Drive Path                                                       Status
    ****************************************************************************
    0   HP.ULTRIUM5-SCSI.000 hcart2 TLD(0)  DRIVE=1 
          /dev/rmt/0cbn                                                    UP
    1   HP.ULTRIUM5-SCSI.001 hcart2 TLD(0)  DRIVE=2 
          /dev/rmt/1cbn 
     
    Any ideas why this is?
     
    Thanks!
  • Mark_Solutions's avatar
    Mark_Solutions
    Level 6
    12 years ago

    As Marianne says i think the original question has been answered but let me clarify and cover the drives too ...

    When writing to disk the maximum number of streams is governed by the storage unit itself only so the number you set here is dependant on the capability of your backup server (disk speed, memory and network)

    The multiplex value in a schedule relates to tape backups only.

    When backups are duplicated from disk to tape they run one image at a time and so do not multiplex onto the tape - as a result you do not need to set a multiplex level for tape if using disk staging

    Your output shows two tape drives - the first shows UP but i do not see a status for the other one. If it is also UP and does not have a tape stuck in it or anything similar then as long as you tape storage unit is set to have 2 concurrent drives in it both should be used

    Hope all of this helps