Suspending vs Shutting Down VMs on Power Failure

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Paul1977

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#205743 25-Nov-2016 09:18

We have our production servers virtualized (SBS 2011, 2008 R2 Remote Desktop Server, various other miscellaneous VMs).

We've just moved all the VMs onto new hosts, and gotten new UPSs.

Historically I have had it configured that in the event of power failure the VMs gracefully shutdown, followed by the hosts shutting down.

I am wondering if I would be better to configure the new setup to suspend the VMs (rather than shutdown), and then shutdown the hosts. Since one of the VMs is Remote Desktop Server and could potentially have a lot of users logged in when the power failed, if I suspend it presumably when it came back up after power is restored the users could just pickup where they left off?

Are there any issues with suspending the SBS 2011 in the same way?

Basically, is there any downside in suspending the whole virtual environment rather than shutting down all the VMs? In theory would the entire environment just come backup as if nothing had happened?

Thanks.

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Dynamic

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#1677237 25-Nov-2016 09:33

We've found pausing VMs to be effective and have had no negative feedback (admittedly this is with very small installations) aside from the odd error message about things timing out, which you just click past.

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networkn

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#1677238 25-Nov-2016 09:35

Same.

Paul1977

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#1677244 25-Nov-2016 09:42

What I wasn't sure about was how certain things might deal with what they (presumably) see as a sudden clock change (e.g. to VM it will appear that the time suddenly jumps ahead an hour). My main concern is how Exchange will handle it. You guys have done it with an Exchange server?

Dynamic

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#1677250 25-Nov-2016 09:53

We've got small numbers of virtual SBS2011 and virtual Exchange 2013 they have not once needed any attention after being paused. It's potentially no different (from the VM's perspective) than you going onto a physical machine and adjusting the clock forward.

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jaymz

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#1677285 25-Nov-2016 11:21

Personally I wouldn't take the risk of potential corruption of databases (exchange or AD).

I haven't had any personal experience with setting my VM's to pause rather than shutdown during a power failure, but I have had 0 problems with all my sites that are set to shutdown on power failure.

The risks I can see are if the power is out for a couple of hours, the VM is in a saved state then is suddenly playing catch-up to get to the correct time.

As for the ability for users to continue from where they left off, I wouldn't offer that feature what so ever. Although it sounds nice to have, the risks with corruption outweigh any benefits.

If you are having that many power outages that you are investigating this, might I suggest you look to move those users or the site to an Office365 or Google Apps platform?

lxsw20

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#1677292 25-Nov-2016 11:38

Personally I'd stick with your current setup. Do you stop exchange services before shutdown?

Paul1977

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#1677302 25-Nov-2016 11:50

jaymz:

Personally I wouldn't take the risk of potential corruption of databases (exchange or AD).

I haven't had any personal experience with setting my VM's to pause rather than shutdown during a power failure, but I have had 0 problems with all my sites that are set to shutdown on power failure.

The risks I can see are if the power is out for a couple of hours, the VM is in a saved state then is suddenly playing catch-up to get to the correct time.

As for the ability for users to continue from where they left off, I wouldn't offer that feature what so ever. Although it sounds nice to have, the risks with corruption outweigh any benefits.

If you are having that many power outages that you are investigating this, might I suggest you look to move those users or the site to an Office365 or Google Apps platform?

We only very rarely have power outages (I can only think of a couple in the past 5+ years), but want it setup in the best way for if we do.

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Paul1977

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#1677306 25-Nov-2016 11:53

lxsw20:

Personally I'd stick with your current setup. Do you stop exchange services before shutdown?

If manually shutting down I always stop the Information Store first, but I have to admit I don't have that setup to happen in a power failure - just a graceful shutdown of the OS which in theory should be fine I would have thought?

jaymz

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#1677346 25-Nov-2016 12:07

Paul1977:

We only very rarely have power outages (I can only think of a couple in the past 5+ years), but want it setup in the best way for if we do.

Stick the the tried and true way you had before. Let the VM's shutdown gracefully and then let the hyper-visor host shutdown. Less chance of issues.

Regarding exchange, the standard shutdown process from Windows should be all you need to do. The only time you might want to stop the Information Store service ahead of time is to save time with the shutdown process (Exchange can take a long time to shutdown if it gets caught waiting for timeouts to occur)

lxsw20

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#1677387 25-Nov-2016 12:40

Paul1977:

lxsw20:

Personally I'd stick with your current setup. Do you stop exchange services before shutdown?

If manually shutting down I always stop the Information Store first, but I have to admit I don't have that setup to happen in a power failure - just a graceful shutdown of the OS which in theory should be fine I would have thought?

Should be fine, just IME a box with exchange shuts down a whole lot faster when you kill the services first.

mentalinc

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#1677437 25-Nov-2016 14:03

I guess the other question then is, what's the purpose of the suspend function?

It's been developed, tested and released. What's he use case for it if so many are against it's use here...

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Paul1977

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#1677504 25-Nov-2016 16:05

mentalinc:

I guess the other question then is, what's the purpose of the suspend function?

It's been developed, tested and released. What's he use case for it if so many are against it's use here...

It seems pretty split for and against.

For those against, have you had issues from suspending?

networkn

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#1677506 25-Nov-2016 16:08

If you are worried, go the safest route and shut down, not a huge amount of downside to it. We shutdown on our systems in a powercut, though I haven't had any issues I can recall with suspending.

lxsw20

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#1677691 25-Nov-2016 23:27

To be honest I've never used it, but I would be very wary of suspending time critical things like AD.

A company I used to work for had to come back from an AD environment that pretty much tombstoned itself due to a bad NTP server. It's not a situation you want to find yourself in.