TSM Space Reclamation

[philwil2000]

Was wondering if anyone could add some detail around TSM's space reclamation process

What I want to know, is 2 things really:

1. If you have a threshold set to say, 70% and you have 5 tapes of differeing free space, i.e

Tape1 - 75%
TAPE2 - 80%
TAPE3 - 85%
TAPE4 - 90%
TAPE5 - 95%

which tape will it start reclaiming first? The one with the most amount of free space (TAPE5), or the one closest to the threshold with the least reclaimable space (TAPE1). Sense would say that it starts with the tape with the most amount of reclaimable space as it would be able to reclaim more tapes in a shorter period. Wondering if anyone has ever proved this theory to be true?

2. Is there an algorithm that TSM uses to decide which tape to reclaim first, and if so, how does it work

Any input appreciated

 

[moon-buddy]

Was wondering if anyone could add some detail around TSM's space reclamation process

What I want to know, is 2 things really:

1. If you have a threshold set to say, 70% and you have 5 tapes of differeing free space, i.e

Tape1 - 75%
TAPE2 - 80%
TAPE3 - 85%
TAPE4 - 90%
TAPE5 - 95%

which tape will it start reclaiming first? The one with the most amount of free space (TAPE5), or the one closest to the threshold with the least reclaimable space (TAPE1). Sense would say that it starts with the tape with the most amount of reclaimable space as it would be able to reclaim more tapes in a shorter period. Wondering if anyone has ever proved this theory to be true?

If these figures represents the percentage of data on the tape, (assuming that you have set it up to start reclamation if the space used goes below 70%) then none will be reclaimed until one tape goes below 70% full

2. Is there an algorithm that TSM uses to decide which tape to reclaim first, and if so, how does it work

Any input appreciated

All tapes below the threshold are eligible for reclamation. TSM tries to put the data in an orderly manner by node and filespace.

 

[philwil2000]

Those figures represent the free space on a tape, there must be some form of decision it basis on which tape to reclaim first

If anyone has tested this and has real world answers, would be interested in the results

 

[booman55]

Keep in mind only primary tapes in Full status are eligible for reclamation. For offsite volumes they can be in any status.