VMWare vSAN: Controlled shutdown to single host in power failure - does it work?

BlizzardX · 5 Jan 2018 at 02:17

I'm playing around with VMWare vSAN/HA as I might purchase VMUG Advantage. I have a Dell 1920w UPS that powers the 3 host homelab (smooths out issues with power delivery and NZ is prone to power cuts).

In the advent of a power cut, the UPS can keep all 3 machines plus Unifi switch up for 30 minutes before cutting out and shutting it all down. I'd like to extend this as far as possible, and would like to drop to a single host with switch to ensure that I still have domain services etc. running for as long as possible.

With HA / DRS turned on, is there anyway to ensure that I can do a controlled host shutdown on 2 hosts while keeping a single host up? I've configured my VM / Host groups using the 'should' controls to try and keep the key VMs running on a single host and the rest to be on the other 2 hosts... but I'm not sure whether I can then force them to not run when a single host is left? Would the above work and it would continue to keep all VMs running until out of memory and the power the rest up when power was restored?

Just thoughts at the moment and happy to be corrected completely if I'm on the wrong tact... Clearly before shutting a host down it should really be in maintenance mode with HA disabled but in the context of a power outage this might not be the best option.

Thanks,

Chris

BlizzardX · 5 Jan 2018 at 08:10

I guess I'm not! The Dell MUMC application controls the UPS and is installed in a VM that is on the keep running list but that is it. MUMC can talk to the esxi hosts and has can set them to shut down but I don't think it can control HA / DRS at all.

BlizzardX · 5 Jan 2018 at 21:16

Interesting. I'll have a look at that. I'm interested primarily in shutting down the vms not needed, disabling HA / DRS, migrating the others to the final host, shutting down the two hosts. On power up, all 3 hosts should come back online with probably only the essential VMs back up and running as the rest I can start when required - hopefully this can be achieved by using the groups I've defined as that would be much easier.

BlizzardX · 6 Jan 2018 at 07:33

Thanks Caged; I presume if I have defined that I want certain VMs preferring the last host remaining (VMHost1) then ESXi will prefer these running over others that are migrating? E.g. Essentials, MBX1, Zevenet Load Balancer, vCenter are preferred on host 1 and I'm hoping that esxi would migrate these on to the host first and then any others if there is space left before shutting down the rest?

BlizzardX · 13 Jan 2018 at 21:06

Hi guys, thanks for all the replies. I am aware generally of how vSAN works at a simple level and a 3 node cluster is running 2 copies of data and a witness, which is why it is unprotected with a single node loss, I was just hoping that vSAN might have had a bit of stuff built in which it doesn't and understandibly so!

I've been toying with Starwinds vSAN for a while now, just running on the VMWare setup to see how it works. This is a pure replication using iSCSI so it can drop to a single node and still keep all the VMs up but on a 2 node setup it can using heartbeat synchronization in order to avoid node majority... seems fairly resilient from what I can test. Its not contained within the hypervisor kernel so speeds are lower I believe but peoples testing suggest not by a vast amount and for a home network should be fine.

Starwind vSAN is a interesting thing as its free and paid; free has a 30 day console plus virtual tape library and then it reverts to powershell only which can do most of what the console can do... As it runs on windows it can use storage spaces to concatenate drives together or use parity etc.

My options will etiher be 2 node vSAN with witness on separate exsi host which is fine as I have a host in the vsan currently that runs my xpenology with passed through HBAs and so that vm can't vmotion anyway so changing that host so it is a witness and the final host to shut down could be ok, or to run a 2/3 node Starwind vSAN and control VM shutdowns via scripting.

I'm curious if any of you have looked in to starwinds software?

BlizzardX · 15 Jan 2018 at 01:11

Will do thanks, clearly this is not a professional setup and its designed to ensure that my partner doesn't kill me when she tries to access the TV (TVheadend), email, plex etc. I could run it on a single host with my Dell R710 holding lots of memory but then an update to that host will kill all VMs however breifly and I'd prefer some redundancy in that case!