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cnibbles
Contributor
Contributor

Virtual Machine will not start when any vmdk is unavailable

Hi all

I recently had a VI3.5 vm which would not start, the error message was 'Cannot Power on . File was not found. The vm had three vmdk's. Disks 1 and 2 on SCSi (0:0) and (0:1) on the same datastore were fine but the third (0:2) on a seperate datastore I noticed had a slightly different name in the properties to what the actual flat vmdk file was called. So I removed it, re-added it, pointing it to the correct vmdk and the vm started up no problem.

This then begged the question, why if it's not a system disk does the vm not start up anyway? I suppose that ESX doesn't know which disk id the quest OS's system disk but surely most are on Disk 1 and SCSI ID (0:0), Aren't they???

My question to everyone is, has this changed in vSphere? And if not, why not? It would make sense, even if it was a manual funtion to tell ESX which disk is the system disk when the vm is built, that way if one of the other disks should fail, at least the vm will still power up?

I would really appreciate your thoughts on this.

Cheers

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4 Replies
AWo
Immortal
Immortal

Even I don't think that my thoughts are the reason why the guest don't start there are configurations where more than the system disk must be available.

- For Linux you can have the "\boot" partition on SCSI0:0 but the "/" root partition somewhere else. In this case, when the VM would start it would fail if the "/" partition is not available

- You can have a multiboot guest with one OS one one disk and the other OS on another disk.

Of course, VM could let it go and just start it until it fails, but that may end up in boot loops.


AWo

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FranckRookie
Leadership
Leadership

Hi Cnibbles,

The VMware host is in charge of ensuring the integrity of virtual machines. If one component is missing or damaged, the role of the hypervisor is to ensure that the rest of the data is not corrupted.

It does not care how the guest system manages the data. It is not even informed of that.

There are so many possibilities to react to this type of failure that it is better, in general, to let the admin choose the most suitable solution. So, it's better not to start the machine.

Regards

Franck

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cnibbles
Contributor
Contributor

Totally agree with both of your replies, thanks for the info, it really helped!

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DSTAVERT
Immortal
Immortal

A simple example might be where a SQL database has data and transaction logs spread across different drives.

-- David -- VMware Communities Moderator
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