I've noticed in ESXi 3.5 U4 that the disk performance write counters always seem to be doubled. I thought initially this was because I was using SATA disks (ML115 G5 server) on a platform that wasn't entirely supported... however I'm just put in a Dell PERC 5i RAID controller and it is also showing the doubling.
For example, copying a VM from the SATA drive (on motherboard controller) to the RAID-5 datastore, SATA read rate ~43MB/s, PERC write rate ~86MB/s. The actual throughput (size / time) is about the read rate,
Any ideas why?
For the benefit of the search, I solved this issue by re-creating the boot USB drive from the image. I'd been fiddling with the advanced settings (this is a test box) and something seems to have put these counters out of line.
My write counters are again doubled, this time I've not changed anything. I don't understand the update process with ESXi (is it automatic?) - possibly an issue there.