On Jan 2, 2013, at 8:45 PM, Geoff Nordli <geo...@gnaa.net> wrote: > I am looking at the performance numbers for the Oracle VDI admin guide. > > http://docs.oracle.com/html/E26214_02/performance-storage.html > > From my calculations for 200 desktops running Windows 7 knowledge user (15 > iops) with a 30-70 read/write split it comes to 5100 iops. Using 7200 rpm > disks the requirement will be 68 disks. > > This doesn't seem right, because if you are using clones with caching, you > should be able to easily satisfy your reads from ARC and L2ARC. As well, > Oracle VDI by default caches writes; therefore the writes will be coalesced > and there will be no ZIL activity.
All of these IOPS <--> VDI users guidelines are wrong. The problem is that the variability of response time is too great for a HDD. The only hope we have of getting the back-of-the-napkin calculations to work is to reduce the variability by using a device that is more consistent in its response (eg SSDs). > > Anyone have other guidelines on what they are seeing for iops with vdi? > The successful VDI implementations I've seen have relatively small space requirements for the performance-critical work. So there are a bunch of companies offering SSD-based arrays for that market. If you're stuck with HDDs, then effective use of snapshots+clones with a few GB of RAM and slog can support quite a few desktops. -- richard -- richard.ell...@richardelling.com +1-760-896-4422
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