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suhag79
Hot Shot
Hot Shot
‎01-10-2018 05:21 AM

Latency when copy data between the VMs on vSAN datastore

Hi All,

When we copy the 7-8 GB of data between the VMs on same vSAN datastore, below is the latency we are getting. it take 4-5 min to complete the 8 GB data copy with lots of small files.

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We have latest vSAN 6.6.1 + vCenter appliance.  Just wondering, if this looks ok or on higher side ?

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2 Replies
suhag79
Hot Shot
Hot Shot
‎01-10-2018 04:25 PM

Can anyone help to understand this issue

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TheBobkin
Champion
Champion
‎01-10-2018 04:38 PM

Hello suhag79​,

"Just wondering, if this looks ok or on higher side ?"

If you are honestly asking if ~400ms Guest-OS latency seems to be okay then maybe you should consider thinking about this from a functional perspective for a moment (e.g. nope).

What are the vSAN Backend graph outputs during this? You need to determine whether there is an issue on the VM side or the cluster.

Are you seeing anything abnormal or indicative of issues on the cluster, hosts or storage-access in the vmkernel.log, clomd.log and/or vobd.log?

If you want to properly analyse the performance of your cluster, start with the in-built proactive stress tests:

https://kb.vmware.com/s/article/2147074

and vSAN Observer:

https://kb.vmware.com/s/article/2064240

Bob

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