Hi All,
We have recently upgraded a lot of our customers onto 5.5 from 5.1 or 5.0. What we are seeing now is a lot of them are showing very high read latency in the reigon of 50 - 150ms, never any lower or higher but hovers around 100ms. However the write latency normally sits around 5 - 10, although under high load such as a server booting it did shoot up to about 50 - 70 and then went right back down.
The servers are all Dells, some are racks, some are towers, some a few months old, some a couple of years old. They all have the PERC H700/710 RAID card and either SATA or SAS drives. I should mention that ESXI is installed onto the same storage as the VMs are held.
We had a similar issue with a T110 with a H300 in it which turned out to be a VIB from the Dell ESXI load, (they were in the 150 - 300ms range, after removing down to 10ms). However this VIB doesnt exist on these other servers.
I am guessing this has something to do with the raid card, or a driver in 5.5, how can i go about finding the cause, i didnt want to start just removing VIBs and wondered if anyone else had experience with this or what i can do?
