Reminder: Even if you are using collocation, it is NOT true that you need a tape for every client. The number of tapes used is controlled by the MAXSCRATCH parameter on the storage pool.
In our case, we have more clients than we have slots available in the library! And the larger your tapes are, the less practical it is to dedicate a whole cartridge to a client. For example, if you have 400 clients and set maxscratch to 200, TSM will stack 2 clients per tape. So, you ask, "Well doesn't that eliminate the benefit of collocation??!?" No, it works out fine. You get 2 clients interleaved on the same tape. But remember, when you are doing a restore, you don't restore all the data. Even if you have only 1 client per tape, you still just restore only the client's active files - TSM has to space over the inactive stuff. It doesn't really take significantly longer to space over the 2nd clients data, than to skip over the first client's inactive data. The big benefit to collocation is eliminating mount and initial search time on large restores. Still works, even if you have multiple clients on 1 tape. ************************************************************************ 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: Luuk Kleibrink [mailto:[EMAIL PROTECTED]] Sent: Friday, August 16, 2002 5:18 AM To: [EMAIL PROTECTED] Subject: Re: IBM vs. Storage Tek Joni, You gave the following estimations: 3590 9840 9940A LTO 10 GB 20 GB 60 GB 100 GB Production Onsite 1375 689 231 140 Offsite 1600 800 268 161 Total 2975 1489 499 301 Test Onsite 963 483 163 101 Offsite 1324 664 223 135 Total 2287 1147 386 236 Grand Total 5262 2636 885 537 And IBM offered a 3-frame 3584. There are some things to consider with these numbers. 1. Do you use collocation. For your onsite tapes you need at least 1 (often 2, 1 full and 1 filling) for every node or filespace you use collocation for. 2. Reclamation. Reclaiming 20% of a 10Gb cartridge works very well, but with 100Gb cartridges this becomes a very long process. We use 3590K cartridges with E-drives (40Gb capacity) and is is very hard to get a good tape occupancy. This is especially the case for our offsite tapes because we sent them offsite every day and therefor they aren't filled up. When we were using 3490 cartridges we used to reclaim at 50%, now we hardly ever go below 80%. 3. Offsite cartridges. As I said above, it's very hard to fill offsite cartriges to capacity. You have to look at your Backup Storagepool processes. Do you have more than 1 primary storage pool and if so, do you run Backup Storagepool in parallel or serially. How many Gigabytes do you sent off daily. 4. Library capacity, with the above numbers 880 slots would be sufficient because you only have 241 tapes onsite plus your scratch. We are looking at the option of moving TSM from OS/390 with 3590 to AIX with LTO. We are now using appx. 500 40Gb tapes and our estimation for LTO 100Gb at the moment is slightly less (say 400-450 tapes) because of the above mentioned reasons. All these arguments are valid to a lesser extent for 9940A and 9840. Just realize that the higher the capacity the lower the usage (percentage wise). Hope this helps, Luuk Kleibrink Delta Lloyd Netherlands ********************************DISCLAIMER******************************** Deze e-mail en alle daarbij meegezonden bijlagen zijn uitsluitend bestemd voor de geadresseerde(n). Verstrekking aan en gebruik door anderen is niet toegestaan. Delta Lloyd N.V. sluit iedere aansprakelijkheid uit die voortvloeit uit electronische verzending. This e-mail and any attachment sent with it are intended exclusively for the addressee(s), and may not be passed on to, or made available for use by any person other than the addressee(s). Delta Lloyd N.V. rules out any and every liability resulting from any electronic transmission. **************************************************************************
