Rick, I think their response would be something along these lines... The XIV can perform better than other traditional arrays because the [cache miss] I/Os are spread across so many more spindles. I get that. But it seems to be that that can break down when the overall I/O load gets sufficiently high, across all of the spindles. In an I/O intensive environment such as TSM, I think this could be more likely to happen - particularly if you are using XIV for storage pools as well as for database volumes.
I'm still skeptical about how far it can go. I can buy that it has good performance --- for a SATA-based product. But not compared to a pure 15K spindle-based product. Oh, and the SATA drives are larger than the SAS or FC drives, which doesn't help. ..Paul At 01:57 PM 10/8/2010, Richard Rhodes wrote: >> I would be suspicious of having the db on XIV. Do you have any FC >> or SAS Disk you could try putting the DB on? I know XIV has lots >> of CPU & cache, but underneath it all is still SATA. I've heard >> Marketing types rave about how fast XIV is, even with SATA, >> because I/O can be spread across many spindles, but I'm not >> entirely convinced it's as good as 15k FC or SAS. > >This is _exactly_ what IBM has not, and seems unwilling, to explain. > >Soon after IBM finalized the purchase of XIV, they had a series >of seminars around the country (usa) about the box. This wasn't some >little out of the way seminar . . . Moshe (inventor of the box) >was there and gave much of the presentation. I attended one - Lets >just say it was strange!!! They hammered on "high performance", over >and over. They threw up one graph where they claimed 25k iops at >3ms response time for a "cache miss" workload. Lets see, cache miss >means having to go to the spindle to do the I/O. SATA drives come >no where close to this response time. The workload was either >not cache miss, or, they effectively short-stroked the drive such >that the heads never moved. When I questioned this claim I >got nowhere - just run-around. > >Rick > > > >----------------------------------------- >The information contained in this message is intended only for the personal >and confidential use of the recipient(s) named above. If the reader of this >message is not the intended recipient or an agent responsible for delivering >it to the intended recipient, you are hereby notified that you have received >this document in error and that any review, dissemination, distribution, or >copying of this message is strictly prohibited. If you have received this >communication in error, please notify us immediately, and delete the original >message. -- Paul Zarnowski Ph: 607-255-4757 Manager, Storage Services Fx: 607-255-8521 719 Rhodes Hall, Ithaca, NY 14853-3801 Em: p...@cornell.edu
