IBM DASD Wow!

At my current gig, we have been evaluating DASDs from both Hitachi and IBM. Both providers want to be my client's supplier. Yep I work for a client with some clout. In the race to be the DASD provider here, each side is one-upping the other. Here's the latest scores..

The applications that I am tuning are pretty heavily IO bound; 70-80% of the elapsed time is in IO wait. So even the smallest increase in DASD performance could have a fairly significant impact on overall response time.

In our previous runs the Hitachi DASD was performing quite nicely (better than IBM). We were able to push up to 50,000 IOs/sec with around a 7ms response time. Hitachi thought we could go much higher, but the test app wasn't driving enough load. When running our real applications full-boar, we were seeing IO response times between 6-7ms.

IBM's turn.. With the latest DASD, we were able to push up to 90,000 IOs/sec with around a 4ms response time ! When asked about how they were able to do that.. IBM gave us a we are in the patent process on our new caching algorithms, so it's a secret type of answer. Now when running our real applications full-boar, we are seeing IO response times between 2-3ms!

When a free-ish market system is working, there really isn't anything that beats it. Here we have two vendors duking it out for business. It is awesome to see how much this competition has stimulated innovation..

Update The new caching algorithms aren't a secret I guess.. the attachment is a pdf describing how they do some of their magic.