HDS’s Chief Science Fiction Officer Claus Mikkelsen writes a missive about how unfair it is to point out usage recommendations for the use of UVM with externally attached storage. He writes:
And, I might add, being a performance claim, it is very conservative in its recommendations.
Well lets examine this new found conservatism.
Today and at product introduction OLTP workloads run on externally attached FC Drives have been listed as “Not Recommended” in Hitachi’s UVM manuals but this wasn’t always the case.
Indeed two years ago the status for OLTP on FC was changed to “Ok” using their old recommendation format. (Today that would be “Yes” the word “Ok” obviously not inspiring enough customer confidence)
I spotted it. A bunch of us spotted it. We asked the Performance Labs to look into it for us. After significant testing Performance Labs determined UVM on the latest hardware wasn’t performing any differently after the documentation bit flip.
Nothing. Zip. Not a jot. No change in performance what so ever.
So someone at Hitachi decided to pull the trigger and change it for a non-technical reason, it having been “Not Recommend” since they started putting the chart in the manuals on Day 1 when UVM was first introduced.
Fine, their chart their recommendations.
But they’ve changed their mind as the recommendation for OLTP on FC has been downgraded back to “Not Recommended”.
This was after customers were told OLTP on FC was “Ok”.
Apparently it wasn’t “Ok”. It might not have even been close to “Ok”.
And since Claus is happy to discuss this now, I think we’d all be interested in hearing what customer experiences forced that recommendation to be returned to “Not Recommended”.
You changed the recommendation, people used it as you recommend it and then it was changed back after people started using it, for reasons which were never explained.
But we can all take a very good guess at why it was changed…
