jondehen
Contributor
Contributor

Help! Redundant Switches - To Stack or Not?

We would like any advice on "best practices" for how to setup redundant physical switches that connect our ESXi host(s) to a NFS NAS via 10GbE. 

Please see the two attached diagrams.  We cannot decide between stacking the switches or leaving them unstacked and separate (and using NFS multipathing).  I wanted to make sure either scenario was feasible.

STACKED

The primary downside I see to stacking the switches is that we wouldn't be able to do firmware updates without taking the entire cluster offline, because both switches in the stack would reboot at the same time.  Firmware updates are rare, but I want to be able to do them without shutting every VM down.  This is a significant disadvantage of stacking to me and I would like to avoid stacking if only for this reason.

In a stacked scenario, we would most likely employ LACP on the NAS for redundant links to the switch stack, although I suppose we could still try multipathing with two NAS IPs.  I understand that I would probably use IP hash if we setup LACP instead of the default NIC teaming.

UNSTACKED

I believe we would have to use multipathing if we do NOT stack the switches and want to keep a single VMK.  I don't know which option I would want for the vmnic teaming in this scenario.

My understanding is that round-robin is used with multipathing, so vmnic1 and vmnic2 would choose either of the two NAS's IPs automatically.  This is why the switches would need a link between them, so that either vmnic could connect to either NAS IP through either of the switches.

This setup would let us reboot either switch without taking down the entire cluster.

Can anyone offer any insight into either STACKED or UNSTACKED design, or using NFS Multipathing in general?  Am I overlooking anything important, or should either of these scenarios work?

PS: I think both of these models cover if either switch were to have an actual outage.

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5 Replies
a_p_
Leadership
Leadership

One quick question. Does your NAS system support Adaptive Load Balancing (ALB)?

André

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jondehen
Contributor
Contributor

Actually, it does support ALB.  It also supports LACP, balance XOR, or Active/Standby.

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a_p_
Leadership
Leadership

In this case I'd go with ALB, which doesn't require stacking, or channeling for utilizing both NICs/paths.

Standard vSwitches btw. support LACP only in static mode, so you would probably not get the expected result anyway.

André

jondehen
Contributor
Contributor

André, thank you, I wasn't even aware that ALB existed on my NAS.

Question: So would the attached topology work then, using two separate switches, one for each of the NAS connections?  If so, I think I would like to use ALB on the NAS instead of NFS multipathing from the ESXi host.

I would assume vmnic1 and vmnic2 would remain setup with the default "Route based on originating virtual port" but I'll have to do more research on this.

Thanks!

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a_p_
Leadership
Leadership

The nice part about ALB is that it works switch independent, i.e. no special configuration is needed on the physical switch side.

However, so far I've often used this for iSCSI (block) traffic with RR multipathing, but never for NFS traffic so far.


André

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