iSCSI SAN / VMware 3850

[Pete Bauer]

Hello - I have a couple quick questions on our VMware / SAN environment.

We're currently running a two VMware host servers (both with 20 gig port-channeled) into a WS-C3850-24XS switch stack.   We also have our SAN nodes connected to this switch stack (port-channeled 20gig).

Everything seems to work OK and we've been running like this for some time but we're seeing a lot of output drops on all the port-channels and physical interfaces (Host servers and SAN nodes).

I'm assuming we're hitting the buffer limits on a 3850?   Is there anything we can do to increase these buffers or shape traffic to help the output drops?

We operate with a very lean budget - if this cannot be done with 3850's properly, what would the cheapest supported switch be for this?

Any insight would be great.

[Kirk J]

Greetings.

You might want to look at https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/200594-Catalyst-3850-Troubleshooting-Output-dr.html 

There's a lot of moving parts here and probably more than a forum post context can resolve.

Can you provide some more detail on your port-channel config, any QOS settings?

Are your PCs carrying both standard ethernet and iSCSI traffic together?  Is iSCSI traffic running on Jumbo frames?

Are you seeing any drops on your VMhost nics?

I had to deal with a limited budget setup similar to yours a number of years ago with 10Gb iSCSI and some 3750x's,,, and it was nothing but headache until we finally got some N5Ks.

Thanks,

Kirk...