HPE EVA Storage

Slow read speed on FATA diskgroup

Ole Thomsen_1
Trusted Contributor

Slow read speed on FATA diskgroup

We run vSphere virtual machines on EVA4100, high performance guests on FC disk group, low performance on FATA.

But performance on FATA is even lower than expected.

I tried to run disk performance tools from inside a guest on both FC and FATA, and FC performed well.

But to my surprise write speed on the FATA were quite good, while read speed were much lower.

Can anyone explain this behaviour? Is there a way to troubleshoot this?

Path selection policy is Round Robin, one controller is preferred for FC LUNs and the other for FATA (failover/failback).

Ole Thomsen
Niels Vejrup Pedersen
Respected Contributor

Re: Slow read speed on FATA diskgroup

Hi Ole,

Do you have some test numbers, and configuration specs ? (number of disks, ioMeter results or similar).

An explanation for writes being fast is often that these go directly to controller cache - and afterwards to disk.

To troubleshoot these things i usually setup evaperf in combination with looking at the OS performance counters.