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We had a situation yesterday where the virtual machines on one of our ESX hosts were taking 10 minutes to boot. This is with only one other machine running on the host. We decided to reboot the host which fixed the problem.

Unfortunately, we don't know why the virtual machines were slow in the first place. We're happy to reboot the ESX host regularly, but don't know how to tell when this is necessary. How can I tell that an ESX host needs to be rebooted? Up until now I thought that it would only need to be rebooted when installing an update, if ever.

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When do you reboot an ESX host? When there's a problem with it. Obviously if the hosts and guests are running fine then you wouldn't need or want to reboot the host. This may sound trite but there really isn't a good answer. When do you reboot a piece of equipment? When it needs to be rebooted, which should be fairly evident.


My apologies for the misunderstanding. My answer didn't state that you should reboot it regularly. My answer stated that you should reboot it when there's a problem. How else would you know when to reboot it? If things are running fine, would you reboot it? When things are not running fine is it apparent to you that they're not? In your first comment to my answer you said that you couldn't wait around to recognize a problem and you need to be proactive so I said to regularly reboot it then. You can't have it both ways. You either wait for the signs of a problem or you reboot it regularly.

Q: "How do I know when to reboot it?"

A: "When things aren't running properly."

Q: "But I can't wait around for a problem, I have to be proactive".

A: "Then reboot it on a regular schedule".

I don't see any other way of looking at this.

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If I take a reactive approach to the problem, though, I'll be out of a job. I need to have a reasonable plan. – Michael Hedgpeth Jan 28 '11 at 13:50
Are you going to be proactive and reboot it when it doesn't need it? A better approach would be to say "We're not going to wait for a problem, we're going to reboot it on a predetermined schedule to avoid having to be reactive to a problem", which makes your question moot because you won't need to "know" when it needs to be rebooted because you're going to reboot it whether it needs it or not. - When should I eat? When I'm hungry. If I'm not going to wait until I'm hungry then I don't need to ask the question. – joeqwerty Jan 28 '11 at 14:01
My question was if there was a good way to determine if you need to reboot. Your answer doesn't help in this regard, other than to say that I should be doing so regularly, which contradicts the other answer. – Michael Hedgpeth Jan 28 '11 at 14:15
@Michael - the point is that you only need to reboot a VMWare ESX host when you need to. You don't need to reboot it on a schedule for the sake of rebooting it, but you might say "We're going to check for patches every month, and the box is at risk of a reboot at that time" – RobM Jan 28 '11 at 14:48
@Michael: See my edit. – joeqwerty Jan 28 '11 at 14:48

In general, after initial testing, we reboot our hosts as part of patch applications when they come out - that's always been fine for us - so about once every few months I guess, never for the hell of it though.

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