TSM compression is good when you are network poor and CPU rich. Now to your question. I cannot figure out how you are in this quagmire. First of all, the estimated capacity of a tape is just that, "ESTIMATED". To my knowledge it has no actual bearing on the pool fill. What determines the utilization of a tape is its actual fill or the estimated if it is still in a filling state. A tape in a filling state will not reclaim unless it is marked readonly and meets the reclamation criteria, or at least I have been told that.
Now, the question, how many tapes are in a filling status. How many of those are marked readonly and over the reclaim threshold. If it is a lot then you are getting a lot of media write errors that are marking the tapes readonly. This could be a bad tape drive or a bad batch of tapes, or tapes destroyed by a bad tape drive. So, what do we do? We defined our 3590K tapes as 100G each. We set the number of scratches in the pool. They all generally fill up. But, we do not have collocation on the pool. If you have collocation turned on, you are fighting a misinformation battle you will never win. So, what do you need to do. The correct thing to do is do a count of the volumes in a pool if you are using MAXSCRATCH and make sure you have enough scratch volumes to continue operation. Select library_name, count(*) as "Scratch Volumes" from libvolumes where status='Scratch' group by library_name If you are defining volumes to a pool, you need to count the number of empty volumes in the pool. Select stgpool_name, count(*) as "Empty Volumes" from volumes where status='EMPTY' group by stgpool_name. Now, as to your comment that the tape is 33% full is marked as filling. The reality is the tape never filled up. I have many tapes in my library that are status=FULL that are less than 100GB. Again, it is only an estimate. Let your operators know that TSM has no idea how much tape is left in a cartridge. Until the tape fills, you have no idea how much data you can fit on a cartridge. Case in point. I have tapes that are full that have as little as 39GB and as much as 617GB. The storage pool PCT_UTL is a bogus number, means nothing in the high-end tape technology. Where it was really useful was in a WORM or tape technology that had no compression. You can find out your largest and your smallest with the following: Select max(est_capacity_mb) from volumes Select min(est_capacity_mb) from volumes You will find that that number is not estimated when the volume is full. It is actual. But if the data was compressed on the client, then this is the compressed data size sent to the server not the orignal data size. I hope this will help you. If it does not, call me or send me an email. It may turn out there is some kind of limitations that I am not aware of in 4.1.6, but I do not think so. Paul D. Seay, Jr. Technical Specialist Naptheon Inc. 757-688-8180 -----Original Message----- From: Rob Schroeder [mailto:robs@;FAMOUSFOOTWEAR.COM] Sent: Monday, October 28, 2002 6:48 PM To: [EMAIL PROTECTED] Subject: 3590 compression vs tsm compression Win2k SP2 client 4.2.1.32 Win2k Sp2 server 4.1.6 (Iknow I know) Here is my dilemma: I have been setting the size of my 3590E device class to 39 Gig (just under the 40 gig size limit) and have been doing compression within TSM. However, due to the number of clients and the server size, I would like to have the hardware do more of the compression to alleviate the processor bottlenecks I have. Therefore I have tested changing the tape capacity to 120G and turning off TSM compression. If the tape gets less than ideal compression (assume none) then when the tapes get 33% full and thus TSM lists the tape as filling. The backups still think there is no more room in the storage pool. I am then left with these situations: 1. TSM must mount the tape before it recognizes there is no more room. Obviously this is bad if there are 100 tapes and it takes 2 minutes per tape to mount. 2. TSM reclamation thresholds are shot because it wants to reclaim at 50% utilization but will never get there because it can only go as high as 33%. 3. My operators think that there is lots of room in the storage pool because there are 100 tapes at 33% utilization leaving most of the tape available, and they don't add tapes even though they are needed. Do I need to continue to use software compression and forget about the hardware side? Any thoughts would be helpful. Rob Schroeder Famous Footwear 608-827-3495 phone 608-662-6495 fax
