Greetings,
        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?
        With real tape drives, a TSM server (in my case, AIX) doesn't have
to worry about large numbers of real drives, because it would be cost
prohibitive to have 50 or 60 real tape drives on a single TSM server.
        But now that there are virtual tape products, like the Clariion Disk
Library, that allow you to drive a large number, can the resources on the
TSM server prevent you from having large numbers of virtual tape drives?
        I have on customer with 64 virtual LTO2 drives on a single AIX TSM
server (a 8-way 6M2 with 16GB memory), and it seems to be able to use them
all simultaneously without running into any limitations, except for the
speed of the incoming data, which is limited to the size of the incoming two
Gig-E networks sending the data.
        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?

Best Regards,

John D. Schneider
Technology Consultant