Tape usage logic

[pkelly_sts]

Just curious as to what logic/rules Veeam uses for tapes when choosing which media to use next when the current one is full.

Choices I'm aware of are:

1. Tape in the target pool that is already expired
2. New/unused tape that has been manually added to the target pool but not yet actually used/written to
3. Previously used tape (perhaps previously in another pool) and now manually moved to the target pool
4. Previously used tape (perhaps previously in another pool) and now manually moved to the Free pool
5. New tape, never used, available in Free pool

We have a library with LTO-6 & LTO-7 drives and I'm starting to direct backups to the LTO-7 tapes instead but curious as to how it chooses the next tape to use so would love to be pointed to a clarification if one exists somewhere?

[Dima P.]

Hi Paul,

In current version the general rule would be to use new tape instead of expired tape as long as new tape is available (to provide more restore time), but when it comes to the choice between two expired tapes the selection is random.

By the way, in U4 we start to track the tape usage and will select the tape based on it’s life cycle (to span tape usage across all media, instead of constantly reusing one particular tape).

[lyapkost]

Hi Paul.

That logic is a subject to improve. The proper priority should be like this (from higest to lowest):

1. Partially written tape if it's media set is not closed (if there are several, the one with more free space has higher priority).
2. Free tape from the current media pool (and current media set if it's a GFS media pool).
3. Expired tape from the current media pool.
4. Free tape from the Free media pool (if checkbox 'add tapes from Free pool' is checked).

Other things being equal, the tape currently in drive has higher priority.

It's also planned to prioritize tapes according to the number of write cycles and take least used tapes first.

[antasik]

"General rule" logic is a bit inconsistent. B&R prefer taking new tape from "Free" pool "to provide more restore time" but write on expired tape is done randomly instead prefer oldest tapes.

[Dima P.]

antasik,

We plan to select the expired tape based on it's lifestyle as I explained above

[srdegeus]

Hi Paul.

That logic is a subject to improve. The proper priority should be like this (from higest to lowest):

1. Partially written tape if it's media set is not closed (if there are several, the one with more free space has higher priority).
2. Free tape from the current media pool (and current media set if it's a GFS media pool).
3. Expired tape from the current media pool.
4. Free tape from the Free media pool (if checkbox 'add tapes from Free pool' is checked).

Other things being equal, the tape currently in drive has higher priority.

It's also planned to prioritize tapes according to the number of write cycles and take least used tapes first.

I would propose to change the order between 2 and 3.
I would like to know that I have free tapes in a media pool that could be allocated to another pool. On top of that, I want my tape data to be overwritten as some data we are legally not allowed to store longer than strictly necessary.

to use new tape instead of expired tape as long as new tape is available (to provide more restore time)

makes no sense as this 'restore times' is defined by the retention policy. There should not be a hidden way for data to exist for a longer time than defined.