No, you don't need to put anything off-line. We'll handle time consuming operations @ the background to save IOPS.
ReFS has the same "free space bitmap" concept as it's basically stripped down version of NTFS.
Other file systems (like VMFS) can deallocate free space automatically as they know how to tell to array particular block pattern is not used. We do understand them. NTFS is not that smart.
Aitor_Ibarra wrote:Surely this would have to be run with the target offline? If you have spare disk space, especially on different set of spindles, it would make more sense to me to create a new de-dupe target and then copy the data across from the initiator side. How you do this would depend on the application, but you could probably do it more quickly and with less disruption. And without the worry that this tool won't understand the filesystem - in Windows land you've now got ReFS support to worry about too...
E.g if it's an Exchange mailstore, just create a new one on the new target and migrate the mailboxes. If it's a Hyper-V VM, use SCVMM to do a storage migration...
However if it can be done with the target online, even if it takes forever, it could be a very useful tool for people who don't have spare disks...
