Hi,
1. the basic Performance metrics:
array stats (evaperf as)
controller stats (evaperf cs) -
host port stats (evaperf hps) - IO latency
physical disk group stats (evaperf pdg)
you can run this 4 in a separate CMD windows and you can see the overview of the perf situation
(combine it with the -csv operand to import the data to e.g. any perf grapher or excell itself)
2. then according to the bad host port statistics you can run specific
vdisks performance data evaperf vd -fvd
The key performance parameter:
1. IO latency
values:
a) read miss latency
<10ms =ecxellent
10<20ms =very good
20<30ms =acceptable
30ms and more =unacceptable
b) write latency
<5ms (with write cache enabled) =ok
5ms and more =unacceptable,
we need to check the physical disks IO request queuing (evaperf pd, pdg)
>1.5-2 queue depthts - not enough spindles in a disk group (add more physical disks)
2. Host queue depth (hc)= io requests at a time
example: the default queue depth per host HBA for the windows server is 32. If the actual values are less then potential workload, then we can say that the host is not giving the array enough work to do. If it is equal/similar, the HBA server side queue depth settings should be tuned
the pain is one part of the reality
