meaning of "VirtualDisk|Read_Latency"

[TheVMinator]

Does virtual disk | read_latency correspond to GAVG in ESXtop or a different metric?

https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=10082...

[Madmax01]

Hi there,

so the virtual disk   Read/Write latency   you could double check then with   GAVG/cmd,  GAVG/rd, GAVG/wr

G = Guest Latencys

if you seeing higher GAVG Values > then you should double check on esxtop where it comes from.

at first you could look at

CMDS/s

MBREAD/s

MBWRTN/s

DAVG/cmd

KAVG/cmd

if you facing high DAVG and KAVG > then possible cause is somewhere on youre StorageDevice and Kernel getting Troubles. Most Cases for high DAVG are Performance Bottlenecks once driving lot of I/Os  or MB/s. each Disk is only able to cover an special amount of I/O or MB/s.

Best regards

Max

[dtaliafe]

I would think that "virtual disk | read latency" corresponds more closely to LAT/rd in the virtual disk view "v" in esxtop since vROps has it on VM resources, but that's just a logical guess.  GAVG in esxtop is for the host adapter, i.e. vmhba0, vmhba1, etc., and is for both reads and writes.  vROps has DAVG and KAVG under the host disk metrics, but I haven't found one that looks like it matches GAVG.

[TheVMinator]

Thanks all for the input. At first when vROps came out understood it was a purchased product with poorly documented metric definitions.   After all the years that vROps has been out, I confess I'm troubled that a metric as common as read_latency doesn't have a clear, specific definition - one  that is published without attempting to manually run ESXTOP and try to find what looks equivalent and assume that it is the same if the numbers look the same, and one that relates it to what we are used to in ESXTOP. 

Anyone else have any conclusive ideas on the definition of what "virtualDisk|Read_latency" exactly is?