Determining Remaining/Total Tape Capacity

[rbenavram]

1. How does TSM caculate how much capacity is left on a tape volume?

2. How does TSM know if hardware compression is enabled in the tape library/drive. How does hardware compression figure into the calculation of capacity?

3. If I do a "q vol tape_pooL status=full" why do "full" tapes (all of the same type) have different "estimated capacity"?



Thanks,

Richard

ADT

Boca Raton, FL

 

[AndyRH]

1. I do not believe it does. It simply tells you the percentage left of the capacity you gave it.

2. In my case, I do not believe it knows. (3590-E tape drives, AIX server)

3. Estimated capacity starts at what was defined when the drive class was setup. If more than that amount of data fits on the tape, then the number rises. You should also notice that the PCT UTIL number is based on the defined number.



For example, this is from one of my TSM servers. All of the tapes are of the same kind, all have 40gb native capacity. Notice that one is filling and has more data than one that is full?





Volume Name Storage Device Estimated Pct Volume

Pool Name Class Name Capacity Util Status

(MB)

------------------ ----------- ---------- --------- ----- --------

T00276 COPY_TAPE 3590-A 104,307.2 100.0 Full

T00384 COPY_TAPE 3590-A 76,717.9 100.0 Filling

T00583 COPY_TAPE 3590-A 59,499.5 100.0 Full



I hope this helps.

Andy