difference between cloning and cold migration

[RUG201110141]

We have a vSphere 4 environment (vCenter 4.1.0 build 799345 and ESXi 4.1.0 build 800380).  Generally when I have to move an virtual machine from one ESXi cluster to another in our environment I power it down and migrate it.  I have a request that I don't normally entertain, but the user wants me to copy the machine from one cluster to another and leave the copy powered off in the originating cluster just in case something goes wrong.  I'm fine with that but I was wondering what the mechanics / differences between the cold migration, which I normally do, and clone are?  If I power off the machine and clone it to a new location I would get the results the user is looking for.  Is there a difference between how the files are moved (i.e. migrate moves through the backend storage and clone uses the management network)?  I have a limited amount of time to perform this operation and I don't want a clone to prevent me from getting this move done.

[vmroyale]

the user wants me to copy the machine from one cluster to another and  leave the copy powered off in the originating cluster just in case  something goes wrong.

This is exactly what a clone would accomplish - a new copy of the original with both intact. A cold migration would just move the single VM to a new location and you would still just have a single VM.

How large is the VM and how much time do you have?

Do you have backups of this VM that you could restore for the user, as opposed to performing a clone operation?

Clones can happen while the virtual machine is running also - can the user live with inconsistent/stale data?

[sparrowangelste]

one thing with a clone vs migration is that you get new macs for your nics in case your software is licensed per mac address.

[RUG201110141]

the mac changing I don't have an issue with.  It's just how long it takes to migrate vs. cloning.  I was wondering if they are done differently or if I can rely on them to take the same amount of time to complete.   Thanks for your reply.

[RUG201110141]

yes I have backups, but the backup would take a while to restore.  I was going to clone the machine while it is powered off so that the machine is in a consistent state instead of using the backup / restore route.  The machine is about 330GB is size.  I just moved a 300GB virtual machine last evening and it took 4 hours to move so I'm anticipating it taking a similar amout of time.  I know a clone with take a snapshot of a virtual machine and then copy the machine to the new location and a migrate just moves.  I was wondering if there was somehow a significant difference under the covers in how this happens which would effect how long it takes.

[sparrowangelste]

I dont think there is a significant difference between cloning, and cold migration time wise, because the data still has to be read from the source and written to the destination. at 330 gb, i think the diffrences are probably insignificant. .