Expiration & Reclemation processes question

[avinim8]

Hi,
I would like to know what is the exact method in which TSM is reclaming data.
Once the expiration date is arrived (or once I manually delete file systems for node), the file/ file system is marked as "To Be deleted".
if I am right, what happens next? what about the tape that contained that file?
The file is not physically deleted from the tape - is the space that was used to store the file on the tape is now writeable? or that utilization of the tape is not recalculated until the reclemetion proccess is reclaming the tape?

bottom line, can i write a new backup onto the same space used to store previous data?

Thanks
Guy

 

[max]

hi,
space on tape is freed up right after expiration runs. You can't write the new backup data onto the same space because tape is a sequential device (e.g. it can only append data): that space becomes eligible for reclamation though.

cheers
max

 

[avinim8]

Thank you Max.

 

[xiewadu]

I always thought that during expiration, files are marked for deletion, but remain in a usable state until the next backup/archive of the client node occurs.

Am I incorrect in this thinking?

Curiously yours,

Jen Howland
Hershey, PA

 

[n9hmg]

yep. The backup is when the TSM server learns the current status of the object. Expiration compares the status with the expiration parameters and deletes the object.

Perhaps Jen is thinking of the fact that until a new backup (or other process) overwrites the space occupied by data that is expired from the TSM database, one can, as an emergency measure, restore a database backup from a time before the data was expired, as a way of gaining access to the expired data. Nasty involved process, but it CAN be done.

 

[avinim8]

What about File device? Can I assume it's different?
When data is stored on file devices and then expired or manually deleted, the file capacity is decresing and the space is writeable immidiatly? I guess so but need to hear you guys.

 

[max]

hi,
a file device acts exactly as a tape would, it is treated as a sequential device and should be reclaimed to free up space.
The only device you can write "in between" is a random access device, e.g. a disk device

cheers
max

 

[xiewadu]

Thank you for clearing up my confusion *grin*!
- Jen