Planned Network Outages

[tractng]

Hello,

We are told to plan for a complete network outages of about half hour to one hour due to network upgrade of the core.

We have one SAN with datastores servicing iSCSI and NFS. Connections from the hosts are on etherchannel to the switches.  So my question and from experience, the VMs need to be shutdown and the hosts should be also shutdown correct? 

My test lab in the past showed inaccessible whenever the SAN when offline.  Our production is 7U3 vCenter/ESXi hosts.  Thanks for your feedback.

TT

[pmichelli]

Ask your network team if the outage includes loss of connectivity between ESXI and the SAN. Some companies have separate switches for storage.

If yes, then you have to power all the VMs off or you run the risk of corruption

If no, keep them running.

[jmontgomery2]

I agree with the other response.  The dependency will be upon whether or not the iSCSI etc connections are included in the scheduled outage.  If it is bypassing what is being placed in the outage then you should be ok. 

[tractng]

It includes everything on the network end to be down.  I am assuming besides powering the VM, the hosts have to be powered down too?

if we leave the SAN on, once hosts and VM are powered on they will auto connect?

We are trying to avoid turning off devices as much as we can.

[pmichelli]

Power off all the VMs. You can leave the hosts on if you like.  You may need to rescan the iSCSI adapter if it doesn't refresh on its own, once the maintenance is completed.

Edit : I would put the hosts in maintenance mode. If you are running ESXi / vCenter 7.x , you will have vCLS VMs still running as part of the cluster health.  They will disconnect and may give issues when the network comes back up

[tractng]

So for the last host on the cluster, we log into the host directly and shutdown vCenter and place host on maintenance?

[pmichelli]

Correct.

Login to the last host and shut down vCenter, then place the host in maintenance mode.  Then do the reverse to power it on once the network comes back.  Once vCenter us up, you can start taking the hosts out of maintenance mode and start your VMs

[tractng]

So for the vCLS VMs, do I need to shut them down on the host they reside?  Several weeks ago I remember placing a host on maintenance and noticed the vCLS VM moved by itself.  

[pmichelli]

If they run on your SAN, they are going to get disconnected during the outage.  They are self managed so your cluster(s) may be able to sort it out.  

I cannot say for certain so take the following at your own discretion:

You can likely just power those VMs off before you shut down vCenter. vCenter will throw errors likely, then just power them back on once the storage re-connects or let vCenter figure out they are off and let it try and boot them.

If you truly want to be 100% safe, power the ESXi hosts off as well. 

[tractng]

Thank you .  I will report back after tomorrow scheduled power outage.

Tt

[tractng]

Here is what we did so it might help others in the future.  We attempted to shutdown the vCLS down but they kept on powering back up.  Was not able to put the last host onto Maintenance mode because of the vCLS were on.  Once vCenter was shutdown, we able to power down the vCLS.

When we powered the vCenter back on, vCLS were automatically powered on.

TT