Esxi with iSCSI SAN slows down with many multiple VMs running

Posted by varesa on Server Fault See other posts from Server Fault or by varesa
Published on 2012-03-25T18:45:32Z Indexed on 2012/06/10 22:42 UTC
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Filed under:

vmware-esxi

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san

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iscsi

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latency

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freenas

I have a server with ESXi 5 and iSCSI attached network storage(4x1Tb Raid-Z on freenas). Those two machines are connected to each other with Gigabit ethernet, and a procurve switch in between.

After a while, if I have many(4-5 or more) vms running, they start to get un-responsive (long delays before anything happens). We are trying to find the reason behind this.

Today we looked at esxtop, and found that DAVG of that iSCSI LUN stays at 70-80. I read that +30 is critical!

What could be causing those high response-times?

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