XenServer - VMs - UUIDs - ??

Dashrender

So, after my crash I was looking at the VHDs that are my system through XenCenter (XC). I have 2 VMs, one has two disks I created through XC and the other only 1. Yet there are 4 VHDs.

I dug around and found the command to tell me the UUIDs of the I think filesystems on the server

 xe vdi-list

This is a really nice command. For the first time I was able to actually tell which VHD files went with what VM I created. Unfortunately, XS doesn't use the filename you give it when you are creating a VHD for a VM.

So anyway, one of the items listed is

 uuid ( RO)                : 8b926d96-ff97-4dc2-8203-016c00fdc0cf
      name-label ( RW): base copy
name-description ( RW): 
         sr-uuid ( RO): 3c68d5fc-2e9f-5f5b-b832-dc1aacf920b4
    virtual-size ( RO): 25769803776
        sharable ( RO): false
       read-only ( RO): true

Any idea what this is?

Could it be related to the fact that I copied (and since deleted the copy) of a Win7 VM I had on the system?

stacksofplates

Another hint, you can tab complete UUIDs.

When you copied the VM did you use fast copy? Fast copy works kind of like the templates, and makes a child VDI based off of the parent. If you delete the base copy the rest of the VDIs are unusable. It looks like this is a base image for a copy you made.

As an aside, this is one thing I want to ask @olivier about. When copying with XO, I don't see a way to select a full copy and not a fast copy with their copy function.

Danp

@johnhooks On a non-running VM, there's a "clone" option where you can choose either fast clone or full disk copy.

stacksofplates

@Danp said:

@johnhooks On a non-running VM, there's a "clone" option where you can choose either fast clone or full disk copy.

I don't know how I missed that. Thank you!

Dashrender

OK that makes completely sense - and seems likely!

So when I created my copy - it spawned this base image, and then a difference file for each different VM that uses the base.

How do I create more copies from that base? The base file doesn't show up in XC in any meaningful way to make a copy of. Instead I just see my original VM, which it itself now appears to be using the base and a difference file.

any way to merge these?

stacksofplates

@Dashrender said:

OK that makes completely sense - and seems likely!

So when I created my copy - it spawned this base image, and then a difference file for each different VM that uses the base.

How do I create more copies from that base? The base file doesn't show up in XC in any meaningful way to make a copy of. Instead I just see my original VM, which it itself now appears to be using the base and a difference file.

any way to merge these?

If I understand correctly, when you make another fast clone of that VM, it will automatically use that base so you really don't need to manually interact with it.

As for merging. There is a coalesce-leaf command to clean up remaining disks, but I've never used it.

stacksofplates

@Danp said:

@johnhooks On a non-running VM, there's a "clone" option where you can choose either fast clone or full disk copy.

I feel like such a moron. That's such an obvious place and I didn't even notice it. I've just been using the regular copy function like a dolt.