Scratch tapes schema

[Fabian_Schwarz]

Hi, 

Can you tell me which is the Netbackup schema to catch scratch tapes ?

[mph999]

Not sure I quite understand what you wish to ask ...

Scratch tapes are just a special pool, that contain 'expired' or 'empty' tapes.  Other pools pull tapes from here as required.

If a tape starts in scratch, is used (so changed to some other pool) and then expired, it will return to scratch.

Tapes that start in another pool, eg. NetBackup, stay in that pool when expired - so for example, if I move a tape manually to NetBackup pool it stays there, even if expired.  If NetBackup pulls a tape from scratch, into the netbackup pool, then it returns to scratch when expired.

Does that help ?

[Nicolai]

Tech note - About scratch volume pools

http://www.symantec.com/docs/HOWTO49122

And you can only have once scratch pool.

[Fabian_Schwarz]

What I really need to know is when NBU catch a scratch tape (in the robotic library) to use in backups.

Need I put scratch tapes in my robotic library when is zeroed (no scratch tapes), or can I wait until NBU

uses all unfilled tapes (no full tapes) ?  

[Marianne]

If you simply need to list tapes in Scratch pool, run this command for tapes in robot 0: vmquery -rn 0 -bx | grep -i scratch If you need ALL tapes for specific density (e.g. hcart3) in scratch pool (including non-robotic): vmquery -a -bx | grep -i scratch | grep -i hcart3

[Marianne]

To know in advance when tape will expire and can be put back in the robot, use the 'Tape Summary' report in the GUI with 'verbose' option selected.
Run this report once a week and save output.

From cmd: 
bpmedialist -summary -verbose

[Fabian_Schwarz]

How the data is writed in tapes ?

Each tape haves data from specific servers ?

[Marianne]

It all depends on your config.

If media sharing is configured, multiple media servers can write to the same tape.

The NBU default is no media sharing.
Each media server will be assigned ownership the first time it writes to a tape. Only that media server can now append to that tape.
When all images ona tape have expired, any media server with access to the robot/media can write to media.

(All documented in NBU Admin Guide I)

[Fabian_Schwarz]

And how can I know if in my NBU environment is seting with media sharing ? 

[Marianne]

You check configuration.

For unrestricted media sharing:
 Host Properties > Master Servers.
 double-click the master server.
 Select Media
Check if 'Enable Unrestricted Media Sharing for All Media Servers' is selected.

For media sharing with a server group, check as follows:
Expand Media and Device Management > Devices > Server Groups.
See if any server groups are configured.
 

All of the above is described in NetBackup Administrator's Guide, Volume I 

Search for 'About media sharing'

[Fabian_Schwarz]

Can you tell me which´s the best moment to put scratch tapes in my robotic library ?

(When it doesn´t haves no one scratch tape or when backup jobs fails with error 96) ?

[Nicolai · Accepted solution]

You really dont need to worry.

If a tape is being freed to re-use Netbackup will automaticaly re-use it.

If the tape if full and put into the robot, Netbackup won't overwrite it before its free.

How many tape per robot only you can tell. It all depen on may tape you use per day. But never go to 0 - Netbackup run best if you have "enough" fee tapes. Enough tapes depend on size, tape pools and retension. For some configuration 2 will be OK, for other 200 may be needed.

[mph999]

Probably best to put them in before status 96 ...

[jim_dalton]

As per mph999, you'll need to familiarise yourself with your data pattern: as  netbackup is predominantly schedule based then your data volumes will follow a pattern. Look through tape reports ->tape written for how many media get used , that will steer you. For eg i know I write 10 media per weekday and 30 on a weekend, so I make sure I have that many in plus 10% for unexpected happenings.

Jim 

[Marianne]

If you run 'Media Written' report on a daily basis, you will get a good idea of how many tapes are used on a daily basis.

Use 'available_media' report (in ...netbackup/bin/goodies) on a daily basis to see available media in the robot (or use my command above to check for scratch tapes).

Always ensure a couple more Scratch tapes in the robot than daily usage.

[Fabian_Schwarz]

Thanks for all answers.