Look at the MAXSCRATCH value for the storage pool. You don't need another 350 tapes. You can use MAXSCRATCH to strike a balance between having a zillion tapes or no collocation at all.
The simplest explanation: If you set maxscratch to 100, TSM will put each client on its own tape until it hits 100 (maxscratch) tapes, then it starts putting 2 on a tape, then 3, etc. What that does is give you collocation, in that each client's data is on a minimal set of tapes, but you get better tape utilization. (After all, setting MAXSCRATCH is the ONLY way people can manage who have more nodes than library slots.) And it works very well from a performance point of view. When you get ready do to a restore for client1, it costs you very little to skip over the data for client2 that is on the same tape (after all, you are skipping over some inactive data for client1 anyway). The point is that you get your client's data on a minimal set of tapes. BTW, you can just set maxscratch and set collocation ON. You can do MOVE DATAs to force the old data to get moved back to collocated tapes as you get around to it, or let it happen gradually as reclaims occur. The only drawback to using MAXSCRATCH is that you have to monitor it regularly. As you get more total data in the library, or as your data gets dispersed onto partially-used tapes waiting to reclaim, you will have to increase MAXSCRATCH. If you don't, as your tapes fill up TSM will start putting more and more clients on the remaining tapes below MAXSCRATCH until you are effectively un-collocated again. ************************************************************************ Wanda Prather The Johns Hopkins Applied Physics Lab 443-778-8769 [EMAIL PROTECTED] "Intelligence has much less practical application than you'd think" - Scott Adams/Dilbert ************************************************************************ -----Original Message----- From: brian welsh [mailto:[EMAIL PROTECTED]] Sent: Wednesday, February 19, 2003 3:43 PM To: [EMAIL PROTECTED] Subject: Question about collocation on/off Hello, AIX 5.1, TSM 4.2.2.8 en 3494 ATL with 700 volumes (used about 620 volumes), and about 300 nodes. Three months ago we turned collocation off because we have about 200 client-nodes with less then 3 GB's data stored, and every node was using min. 1 tape, so we had a lot of tapes with low utilization, long migration. Now tape-utilization is much better, migration is much faster, but yesterday there was a restore of an web-server (WinNT) and we restored almost 2 GB and it took 6 hours and there were almost 70 tape-mounts. Before we set collocation off such restores took half an hour. Now we are thinking of setting collocation back on, but that implies we have to buy and checkin about 350 new tapes, because move data will take weeks or more. Now I was wondering how other sites are dealing with collocation, and what are they doing to get better results during restore, when collocation is off. We are thinking of make a full back-up once a month to get data of one client on less (or one) tape(s), or putting collocation back on, or... Curious to your reaction! Thanx, Brian. _________________________________________________________________ MSN Zoeken, voor duidelijke zoekresultaten! http://search.msn.nl
