SoMoS
Contributor
Contributor

How to recover from a fault with Fault Tolerance machines

Hello,

I have a system running two machines protected with Fault Tolerance. I had a power fail on one machine and the system switched well the machines but when the power returned to the machine that failed the FT protection was not re established automatically.

When I look at the Fault Tolerance box it says that the machine is not protected because needs Secondary VM. I suppose that i could disable FT and enable it again to recreate the machine but, that's the way it is expected to work?

Thanks in advance for your help and your time.

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7 Replies
m2-it-solutions
Contributor
Contributor

Hello SoMoS,

how much hosts do you have? As far as I know, FT needs at least 3 hosts.

when one host fails, the secondary VM gets primary and a new secondary is chosen.

If you only have two hosts, the new secondary can not be established when one host fails.

Bit I'm not 100% certain.

Greeats Martin

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Basheer09
Enthusiast
Enthusiast

When you configured FT was secondary VM created ? If yes what was the status of your secondary VM when you select VM and looked in the summary Tab ?

If you want to create/delete a FT VM you need to Turn on/off the FT.

Kindly elaborate the issue for more details.

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SoMoS
Contributor
Contributor

@m2-it-solutions: The system is composed of 2 hosts. As far as I know the only problem that you have using only 2 hosts is that you have not FT when one machine fails and only another one keeps running. I always thought that when the faulty computer turns back the FT system will be recreated again. I don't see the point to have to click at a button to make this happen.

@Basheer09: As I said at my explanation the system had a fault and it switched from primary to secondary so the secondary was created and the status was protected until the power fail happened. After the power fail was "Secondary machine needed" even when the faulty host had power again.

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kac2
Expert
Expert

FT does not need 3 hosts to function as stated above. FT only needs 2. you have your running VM on 1 host while you have the shadow copy on another host. If your primary host fails, the secondary VM kicks in.

Now, if you had a 3 host cluster, a secondary shadow copy VM will be created on another existing host within the cluster and it will continue on in this loop.

Seeing as how you only have a 2 host cluster, the creation of the shadow copy VM has failed. Therefor, you will need to disable FT on that VM, then re-enable it.

SoMoS
Contributor
Contributor

If that's true it would be a quick win to make the system detect the re establishment of the server and activate automatically the FT again.

Another thing is that yesterday we had another fault and when I went to set FT again it was active ?¿?¿? I will do a programmed fault tomorrow to see what happens.

Someone has a FT system working with only 2 hosts?

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kac2
Expert
Expert

sounds like you need to get an electrician in there ASAP Smiley Happy

Kendrick Coleman

www.kendrickcoleman.com<http://www.kendrickcoleman.com>;

twitter: @KendrickColeman

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SoMoS
Contributor
Contributor

LOL, not really, there are electrical maintenance works in progress and this way we test the FT capabilities.

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