Allen, Thanks for your reply. Rephrasing my question, I suppose what I really want to know is, does a session to a tape drive require more resources from the TSM server than a session to a disk storage pool? If they are the same, then we have no problem. I just had never seen a 200 tape drive TSM server before. EMC (who makes the CDL) will support up to 512 virtual drives (depending on the model), so support from the CDL is not the issue. I just was concerned that the TSM server itself might cave under the strain. Perhaps I am worrying for nothing.
Best Regards, John D. Schneider Technology Consultant - Backup, Recovery, and Archive Practice EMC² Corporation, 600 Emerson Road, Suite 400, St. Louis, MO 63141 Phone: 314-989-3839 Cell: 314-225-9997 Email: [EMAIL PROTECTED] -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Allen S. Rout Sent: Monday, November 07, 2005 11:08 PM To: ADSM-L@VM.MARIST.EDU Subject: Re: [ADSM-L] How many simultaneous tape paths can a TSM server drive ==> On Mon, 7 Nov 2005 16:08:04 -0500, John Schneider <[EMAIL PROTECTED]> said: > This will seem like an odd question, but can anybody tell me how to > calculate the relative impact of tape drives on the performance of the TSM > server? [ ... ] > But I have another customer who believes they need 200 virtual drives, and > that all of them will be working at once. They have that many simultaneous > client sessions going to disk pool, but they would like to drive straight to > CDL virtual tapes, and eliminate the disk pool. Does anyone see a problem > with that? I would say ask the vendor of your virtual tape tech. In theory, there's no reason for the virtual tape behavior to be worse, performance wise, than a similar number of writes to the underlying disk tech. 200 simultaneous incrementals isn't out of whack for a medium sized installation, so you ought to be able to manage the raw I/O. If (? Clariion ?) blanches at the mount count, then you can have a few nice rounds of Vendor Pinata while they explain why. I'm sure some IBMers would be pleased to cough "SANergy" or some such in the background of that conversation. In fact, that was my first question, which I sat on until last: if you've already got TSM in the equation, why would you prefer virtual tape on disk to, say, FILE devclasses? I'm sure there are plenty of good reasons for such a call, but that would be the tool I'd reach for first. - Allen S. Rout