>>" the same thing that happened to the 3466 (i.e. Tivoli does not
recognize it or support it as a true TSM platform) IS GOING to happen to the
3494 system, since it is also somewhat based on the same concept and that if
we implement this, we were almost sure to lose support from Tivoli in the
near future. "That is a VERY weird statement to make. There are a LOT of 3494 installations out there - lots more than there ever were for the 3466, which is a "package" of existing hardware & software. And it's the larger installations (read, those with MONEY) that are using the 3494/3590 technology. It's IBM's premier tape techology, and not likely to go away any time soon. I would be more inclined to think the reason for the statement is that the Tivoli person you spoke to is clueless about IBM hardware (no big surprise). But that aside, performance IS an issue with a VTS & TSM. It depends on your load, mostly, and your time constraints. It can work well, depending on your environment; but you should be VERY CAREFUL about your requirements planning before you do this. TSM is a worst-case application for a VTS. Not because TSM is doing anything wrong, but because ANY application that writes single-file tape images that FILL THE TAPE VOLUME is non-optimal for a VTS. This applies to DFHSM or DFDSS tapes on OS/390 (mainframe) as well. The whole intent of the VTS design was to accept small files that were originally directed to older, small-capacity tapes, store them on disk as "virtual" tape images, then let the virtual tape images get migrated off and stacked together on new large-capacity tapes. When you want to access something on a "Virtual" tape volume again, the VTS has to stage the data from the tape back to the disk before you can use it. If you are talking small application files, the VTS works wonderfully. But because TSM (and any similar application) writes ONE large file that fills the "virtual" tape, the WHOLE TSM "volume" gets written to disk, then staged out to tape. So far so good. But when you want to do a restore of a particular file, the WHOLE TSM volume gets staged back in, not just the piece you want. So it's a performance issue. I know people who use a VTS with TSM and are happy with it. Should work just fine if you have a light load. I also know someone who backs up many GB of data a night with TSM that gets sent to a VTS, then migrated out to tape. Then when they want to copy those "virtual" tapes to create their offsite copy pool ---- takes a lifetime, because each volume has to be staged back to disk first, just to do the copy. They have great difficulty meeting their time windows becuase of the staging time required, and they are less than 100% happy with the results. So THINK TWICE about your requirements before making TSM (or DFHSM, or anything that writes single-file tapes) depend on a VTS. Make sure you understand the performance issues, and that the performance limitations will be acceptable in your environment. Talk to someone on the OS390 support staff about the VTS that exists; how new it is; whether they have sufficient drives and cache capacity to deal with the load you intend to add. You can improve the performance of the VTS in cases like yours by adding more disk cache. Just do your homework ahead of time... My opinions and nobody else's, Wanda Prather -----Original Message----- From: Mahesh Tailor [mailto:[EMAIL PROTECTED]] Sent: Tuesday, October 30, 2001 4:59 PM To: [EMAIL PROTECTED] Subject: 3494+VTS+TSM Hello, all! I am not a 3494 expert, so please forgive my ignorance in the way I refer to this platform. We have a 3494 VTS system/library installed that is currently being used by our OS/390 mainframe for its backups. I would like to know if it is possible for me have TSM utilize this system for it's storage also? Is there any good documentation about how to do this? Also, I spoke with our Tivoli TSM marketing specialist about this and was told, in fairly certain terms, that this was a **BAD** idea because of two reasons: 1) BAD performance 2) the same thing that happened to the 3466 (i.e. Tivoli does not recognize it or support it as a true TSM platform) IS GOING to happen to the 3494 system, since it is also somewhat based on the same concept and that if we implement this, we were almost sure to lose support from Tivoli in the near future. BTW, one reason I ask is that I have a 3466 and am having a hell of a time getting support for this platfrom ever since Tivoli inherited ADSM/TSM and given the strong word of caution from a TSM person at Tivoli, I am reluctant to proceeed with the 3494 integration and upgrade. Can anyone tell me whether any of this is true and lay my fears to rest? In case you don't feel comfortable emaling the list, please send me a message directly and I will ensure that your email stays confidential. TIA Mahesh Tailor WAN/NetView/TSM Administrator Carilion Health System Voice: 540-224-3929 Fax: 540-224-3954
