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Lalegre
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vSAN - Change Uplink order on Teaming and Failover

Hello folks,

Is it possible to change the uplink order on the VDS Portgroup we are using for vSAN without expecting any downtime? We have like this:

  • Active -> Uplink1
  • Unused -> Uplink2

We want it like this:

  • Active -> Uplink2
  • Unused -> Uplink1

Both VMNICs are configured the same in the switch and the VLAN Tagging is perfectly configured we just want to know if that change is feasible without any extra effort.

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depping
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I have never tried this myself, I am guessing it would push it down to the host in parallel. It shouldn't be a problem, but I can also imagine there's a short disruption, so I personally wouldn't do this during peak hours. Although it should still work, I am not 100% comfortable to tell you to just do it Smiley Happy

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5 Replies
depping
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I have never tried this myself, I am guessing it would push it down to the host in parallel. It shouldn't be a problem, but I can also imagine there's a short disruption, so I personally wouldn't do this during peak hours. Although it should still work, I am not 100% comfortable to tell you to just do it Smiley Happy

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Lalegre
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Hey Duncan,

That is exactly what i was thinking but i just wanted another professional opinion regard this. I guess vSAN will keep working but this uplink change is not big deal so i guess we will think on another placement of the Uplinks but for the remaining portgroups.

Thanks!

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TheBobkin
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Hello Lalegre​,

I would advise being very careful when doing such changes as while it may be thought that the unused uplink has the same connectivity to the other nodes as the current one this may not be the case (e.g. if using jumbo frames that it takes a different route and is not 9000 MTU end-to-end) and thus at least for the first host, place it in Maintenance Mode while doing this.

Why not set the unused one to standby, then switch the order, then once confirmed it failed over remove the standby (original active) uplink?

esxtop 'n' option is very useful for monitoring which uplink vSAN traffic is going over when there are multiple links - this is just a case of monitoring it for any traffic and matching the PKTTX/s for the vsan-enabled vmk to one of the configured uplinks (e.g. the numbers will match)- you won't see a massive amount of packets while it is in Maintenance Mode but you should see a small amount of communication from cluster membership heartbeats.

Bob

Lalegre
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Thanks TheBobkin​,

Really appreciate the deep explanation and analysis we will take into account for future changes.

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ManuelDB
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I have tryed it and was not fun. You get 60s of panic, vcenter not responding and a lot of rebuild at the end of the change.

Manage one host at time with VDS and VSAN network and you'll be safe also if you do something wrong

Just my 2 cents

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