Hard disk fully read or only used quota?

[tobia]

Hi,
I noticed that sometimes a VM harddisk is read only for the "used" quota, other times the harddisk is fully read.

For example I have a VM with 4 disks with size of 100GB, these are almost empty, however some of them are quickly read only for the used part, other of them are fully read... why? It depends on what?

Thanks

[Vitaliy S.]

It depends whether you had any data on these disks before or they were newly provisioned. Also with changed block tracking entire disk should not be read during incremental job runs.