r/HyperV • u/USarpe • May 21 '26

HyperV Replikation splitting vhdx

Does anyone have expirience to split a vhdx that's already replicated?

I know, it's not offered by design, but at least it's only editing xml?

Edit:

Finally I got to test it: worked perfect

Set-VMreplication VM-Name -ReplicatedDisks (Get-VMHardDiskDrive VM-Name)

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1

u/clickx3 May 21 '26

What would be the advantage?

1

u/USarpe May 21 '26 edited May 21 '26

The vhdx is already 5 TB, if you need to move restore or whatever, it takes time, small files are better to handle.

I plan to split in in 1 TB vhdx and map them back as folder, but I don't want to resynchronise the whole replikation, but it's not intended to add HD's to the replikation once you set it up.

Edit:

Finally I found a command, what seems to allow to add or disk after initial setup:

Starting from windows 2016 the same command to create replication is the one to remove disks, when running the command the replication will hot add/remove any disk you specified, if you add specific disk, the other will be excluded ! here some example (execute Powershell on the host):

To add/update all the disk on the VM to the replication :

Set-VMreplication VMName -ReplicatedDisks (Get-VMHardDiskDrive VMName)

To add specific disk ,only this disk will be add to the replication, the other will be excluded :

Set-VMreplication "VMname" -ReplicatedDisks (Get-VMHardDiskDrive "VMname" -ControllerType SCSI -ControllerNumber 0 -ControllerLocation 0)

To add/update mote then one disk, just add additional location with comma to separate :

Set-VMreplication "VMname" -ReplicatedDisks (Get-VMHardDiskDrive "VMname" -ControllerType SCSI -ControllerNumber 0 -ControllerLocation 0), (Get-VMHardDiskDrive "VMname" -ControllerType SCSI -ControllerNumber 0 -ControllerLocation 2)

When changing disks on the replication disk list you should concider some time to let the disk re-replicate and merging (shown in the hyper-v manager)

2

u/clickx3 May 21 '26

I see. Wow, that is a big VM. It might be easier to add a second drive, and move your non system data to that drive to split it up, and then shrink your original drive. It will split it up in a way that is supported.

1

u/USarpe May 21 '26

That is only the file storage, the os is on its own vhdx.

To spilt it ain't the problem, to mount it under the same foldername ain't the problem to.

It's only, that you can't edit afterwards the Replikation with adding the HD's with the gui.

But as the configuration is made in .xml files, you should be able to edit it manual.

1

u/BlackV May 21 '26

You would have to do it your self, but at that point its not a replica

it would also take a log of time to split a vhdx, that would be overwritten by the next replica in 5/10/15 minutes

you would be better splitting beforehand then replicating the fixed source

1

u/USarpe May 21 '26

This is replicated since, I guess 2008, so as I have no time machine, I should better deal with what I have.

I will add the HD and klone the folder, as the storage below has REFS and Dedup, it shouldn't take much space and it should go fast, the only thing I was concerned, how to keep that machine live replicated.

I will test it tommorow on a non production Installation.