Decrease disk for vm

[MustafaSadek]

I have vm which is windows and has 3 disks.. disk0 , disk 1 and disk 2 

Disk1 is 500 GB(total size) but has 200 GB unallocated from windows . My question is ..

if i wanted to take back this 200 GB (unallocated ) and assign it to disk 0 to increase disk 0 total size >. if i decreased the size of disk 1  by 200 GB from vcenter or vcloud and assigned it to disk 0 ... is this possible ?

Q2,if possible..Will the decreased size affect on the current data written on disk 1 if it has data already written on os layer (windows ) .. i mean will decreasing the size of disk 1 will pull the size from the unallocated disk on windows or not  ?

[stadi13 · Accepted solution]

Hi@MustafaSadek 

You cannot reduce the disk size in vCenter. I recommend creating a new disk, create a windows partition and then migrate the data on it. After the migration, take the old partition/disk offline and assign the drive letter of the removed disk to the new one. Reboot your VM.

Very important: Create a backup before performing any changes.

Regards Daniel

[Tibmeister · Accepted solution]

No, you can't decrease the size of a disk's allocation.  What you can do is convert Disk1 into a Thin Disk, which will only consume what it needs on the datastore and free space inside the guest OS will not be consumed.  You can also expand any other disk as desired.  That's the closest you can come to moving size around between disks, but, remember that Disk1 will still be able to consume all 500GB if it wanted to.