MPF (Maximum number of partially full media)

[T_N]

Hi All,

Anyone can explain it to me , is it option to have full tape before send it to offsite ? Thanks.

[Dion]

Correct.  This setting reduces the amount of empty tapes for any given volume pool.  Generally you would not need to set this on volume pools that will remain in the library as these tapes will generally be reused the following evening.  This helps with sending partially filled tapes offsite.

Let's say you have 5 tape drives that you use to duplicate your data and you don't have this option set (note that you will also have to have no restrictions on the storage groups.  ie max # of concurrent drives).  NetBackup will load a tape into each drive at the same time.  Once your duplication is complete you will potentially land up with 5 partially filled tapes.

If you say, set MPF to 2 for a volume group (e.g. OFFSITE) this setting will restrict NetBackup to only loading two tapes into drives at a time.  By doing this only two tape have the oportunity of being partially filled.

You will need to find a happy medium between the number of partially filled tapes you send offsite and the amount of time it takes to complete the duplication.

Cheers
 

[T_N]

Thanks, it's great. My library has 12 LTO tape drives, the current setting of  MPF is 0, I use AdvancedDisk to backup client (IE backup to disk first then duplicate to tapes) but when I check in dplicate pool, I don't see the full tape. Anyidea why ?

[tryingtohelp]

I have a libray with 12 drives. My retention for daily backup is 30 days.
I send media offsite for 7days. when media returns, I place them into libray.
Will these tapes be counted as mpf media in libray?
i guess my question is, will these tapes be used before retention expires to append new backups?

[J_H_Is_gone]

Yes, if you put UN-expired media into the library then NB will append to those tapes FIRST before it will choose a scratch tape. (depends on if you do or do not mix retention periods on tape, and what retention period tonight's backups are running with)

For me, if my retention is 30 days, then I leave the media off site for 30 days. It Returns at 30 or 31 days, and is expired before I put it back into the library.

Reason is at some point as the media is append to it get full (tape can only append - it cannot write to the blank/expired portions at the beginning of the tape).  Once the tape is full it will then pull another tape to write to, so now you may be sending off 2 tapes instead of one.