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MikeM11's avatar
MikeM11
Level 4
13 years ago

Netbackup 7.1 Multiplexing

We have a NetBackup 7.1.0.1 environment on Windows with 4 tape drives.

Multiplexing is enabled on the Storage unit with Maximum streams per drive set to 10 and in the policy schedule Media Multiplexing is set to 4.

Currently we have a number of client in the policy performing in-line copies to MSDP and Tape but only 4 jobs are running to tape at any one time.  Can anyone tell me where I am going wrong with this configuration as the Admin Guide seems to confirm this is correct?

Many thanks

Mike

  • Symantec have confirmed that Media Multiplexing does not work in a scenario where inline copies are being used to MSDP and Tape due to the underlying process that runs the multiplexing.  the summary from Symantec is below:

    Multiplexed backup to disk STU is not possible as it does not understand multiplexing and irrespective what its value is it resets it to 1.

    We can send multiple jobs to disk but these jobs are not multiplexed.

    The difference is that Disk writes "concurrent jobs" not multiplexed jobs. 

    Images written to a disk storage unit with MPX>1 are not really multiplexed images.

    NBU writes a separate tar file to disk for each image and each job is actually at an MPX of 1.

    A multiplexed backup is a feature of a tape based storage unit only.

    In these backups more than one stream is sent to the file position on the tape.

    This will put more than one image on the same file position on the tape.

     

    From Netbackup 6.5, new functionality was put into the bptm process.

    Disk writing capability that was formally exclusive to bpdm was put into bptm.

    This will allow a multi copied backup to go to a disk and a tape based storage unit.

    Because these 2 bptm child processes will be copies of one another they must be the same.

    This will require the bptm multiplexing option to be set to 1 (or off) in this scenario.  (Mixing disk and tape multiple copies results in the lowest MPX value being set, if you mix disk and tape this will default to an MPX value of 1.)

    Inline Tape Copy to both disk and tape will not be multiplexed