I received this question a couple of times and there’s no real definitive answer written anywhere…
“Does storage vmotion require additional disk space on the source volume?”
The answer is: Yes it does. Storage VMotion uses the snapshot technology to release the lock on the source disk. This snapshot is placed on the source volume. So in other words, all changes that take place during a Storage VMotion are written to the delta file. This delta file, can and will grow fast.
So keep this in mind if you need to storage vmotion a VM because the VMFS volume is running out of diskspace… it might run out of diskspace sooner than you think.
Vladan says
Hi Duncan,
great info. It definetely need to be taken serious.
And one has to be sure to have enough space on the VMFS volume before start playing with Storage VMotion…
Hugo Peeters says
Hi Duncan,
When I tried to do svmotion a while ago, I also found that I needed free space on the datastore I was moving away from. But that was not the datastore I normally have vm’s store their snapshots on.
Situation:
Datastore A: vmx file etc. + disk 1, free space available, normal location for delta files.
Datastoer B: disk 2, no free space available.
When svmotioning disk 2, the process hung.
So to everybody wanting to try svmotion: test, test, test!
Hugo
Ade(gboskin) says
I have a VM machine with a 30GB OS datastore with 5GB free on the source. This VM also uses an 8GB page file datastore with has no space.
I want to svmotion the vm machine to a new OS 60GB datastore leaving the system to still mantin the 8GB Datastore.
can this be done??