Hi all,

I have a query regarding tape usage:

Analysis: We currently have TSM 5.2 installed on a WIN2k Server platform 
backing up appx. 50 nodes to 2 disk pools and then migrating to LTO tapes in  a 
3583 library, one copy for offsite vault and one copy to remain onsite within 
the tape library. We have 60 available slots for LTO volumes as we  leave the 
I/O drawer free to take volumes in and out of the library. We are using 100gb 
native LTO volumes. We have 3 nodes that are configured to  backup using 
collocation.

Problem: We are constantly running at full capacity within the library (always 
59 Private volumes) leaving only one slot for scratch. Because we have  3 
collocated nodes and produce a dbbackup everyday to go offsite we need a 
minimum of 5 free slots (assuming all other backed up data for other nodes  
does not exceed 100Gb). When I issue 'q eve * * begind=-1' to check the 
previous evenings backups I am usually shown that most nodes have completed  
but often have only 2 tapes to go offsite (inc. the dbbackup) suggesting that 
collocation is not happening. Aside from this, when I issue a script to  check 
what space I am able to relaim from the onsite tapes (in order to free up some 
slots for scratch volumes) I am presented with the following (I  have omitted 
the offsite copy LTOs):


STGPOOL_NAME           VOLUME_NAME            PCT_RECLAIM     ACCESS            
------------------     ------------------     -----------     ------------------
BACKUP_TAPE            000411L1                      43.8     READWRITE         
BACKUP_TAPE            000466L1                      43.5     READWRITE         
BACKUP_TAPE            000362L1                      43.0     READWRITE         
BACKUP_TAPE            000382L1                      42.6     READWRITE         
BACKUP_TAPE            000380L1                      39.6     READWRITE         
BACKUP_TAPE            000529L1                      39.1     READWRITE         
BACKUP_TAPE            000632L1                      38.7     READWRITE         
BACKUP_TAPE            000563L1                      38.4     READWRITE         
BACKUP_TAPE            000418L1                      35.4     READWRITE         
BACKUP_TAPE            000403L1                      34.6     READWRITE         
BACKUP_TAPE            000572L1                      33.7     READWRITE         
BACKUP_TAPE            000364L1                      31.4     READWRITE         
BACKUP_TAPE            000564L1                      28.8     READWRITE         
BACKUP_TAPE            000402L1                      28.5     READWRITE         
BACKUP_TAPE            000495L1                      25.8     READWRITE         
BACKUP_TAPE            000391L1                      25.6     READWRITE         
BACKUP_TAPE            000412L1                      22.9     READWRITE         
BACKUP_TAPE            000453L1                      22.8     READWRITE         
BACKUP_TAPE            000501L1                      21.3     READWRITE         
BACKUP_TAPE            000413L1                      16.6     READWRITE         
BACKUP_TAPE            000612L1                      16.1     READWRITE         
BACKUP_TAPE            000470L1                      14.8     READWRITE         
BACKUP_TAPE            000618L1                      11.4     READWRITE         
BACKUP_TAPE            000395L1                      11.1     READWRITE         
BACKUP_TAPE            000607L1                       6.3     READWRITE         
BACKUP_TAPE            000388L1                       3.2     READWRITE         
BACKUP_TAPE            000422L1                       2.4     READWRITE        
BACKUP_TAPE            000570L1                       2.2     READWRITE         
BACKUP_TAPE            000516L1                       0.0     READWRITE         
BACKUP_TAPE_COL        000463L1                      44.7     READWRITE         
BACKUP_TAPE_COL        000600L1                      42.9     READWRITE         
BACKUP_TAPE_COL        000575L1                      41.4     READWRITE         
BACKUP_TAPE_COL        000530L1                      40.3     READWRITE         
BACKUP_TAPE_COL        000540L1                      37.7     READWRITE         
BACKUP_TAPE_COL        000605L1                      35.7     READWRITE         
BACKUP_TAPE_COL        000417L1                      34.7     READWRITE         
BACKUP_TAPE_COL        000457L1                      33.0     READWRITE         
BACKUP_TAPE_COL        000437L1                      32.4     READWRITE         
BACKUP_TAPE_COL        000644L1                      29.5     READWRITE         
BACKUP_TAPE_COL        000415L1                      28.4     READWRITE         
BACKUP_TAPE_COL        000581L1                      28.3     READWRITE         
BACKUP_TAPE_COL        000583L1                      28.3     READWRITE         
BACKUP_TAPE_COL        000601L1                      27.7     READWRITE         
BACKUP_TAPE_COL        000452L1                      26.3     READWRITE         
BACKUP_TAPE_COL        000414L1                      24.9     READWRITE         
BACKUP_TAPE_COL        000464L1                      23.1     READWRITE         
BACKUP_TAPE_COL        000477L1                      22.4     READWRITE         
BACKUP_TAPE_COL        000416L1                      22.2     READWRITE         
BACKUP_TAPE_COL        000502L1                      20.6     READWRITE         
BACKUP_TAPE_COL        000545L1                      19.2     READWRITE         
BACKUP_TAPE_COL        000360L1                      15.0     READWRITE         
BACKUP_TAPE_COL        000379L1                       7.7     READWRITE         
BACKUP_TAPE_COL        000515L1                       4.6     READWRITE         
BACKUP_TAPE_COL        000596L1                       4.5     READWRITE         
BACKUP_TAPE_COL        000559L1                       1.9     READWRITE         
BACKUP_TAPE_COL        000442L1                       0.6     READWRITE 

By looking at the 'PCT_Reclaim' I can see that 000516L1 has 0% of reclaimable 
space going up to 43.8% for the least used volume (000411L1). What I  have 
tried to do to get some more usage out of my LTO volumes is issue a 'MOVE DATA 
<VOL_NAME> STGP=<DISK_POOL>' to move all the data from the least  used volumes 
(making it READONLY before starting the process so TSM does not reuse the 
volume when it is returned to 'Scratch' status when empty) back  to the disk 
pool to be migrated onto other onsite volumes. In effect I am running manual 
reclamations but as you can see from the output above it does  not look like 
tape space is being managed as efficiently as it could be. I'm not sure whether 
this is to do with the way TSM has been configured or  whether it is natural to 
see volumes used to differing percentages because of expirations, etc. 
Does anyone know how to get onsite LTO volumes to use closer to 100% of their 
capacity or are we expecting too much of our setup - do we need to start using 
200Gb tapes (this will presumably mean we will need to replace our 4 existing 
drives)? Also, there are 27 onsite volumes for collocated nodes but only 3 
collocated nodes - is there something I can  check to ensure this is correct?
Also, I am planning to delete some unused filespaces that will remove appx. 
1.5Tb of data from our backed up data. Will deleting these filespaces  invoke 
TSM to automatically purge the associated data that resides within the 
onsite/offsite volumes and will this mean that we will free up some  slots 
within the library for scratch media?

Hope someone can offer some suggestions.

Regards, C. Adams.

C. Adams
IT Support Analyst
WRC Holdings Limited

 
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