Hello,   It will never (or extremely rarely) exactly match.   In part because of the 15MB page size I mentioned before.  A single write will keep a page fully allocated.  So until an entire page is freed, it can't be returned to free space.  Regards,   Don 
HI, i have a PS4100 storage backend that serves a 1TB thin volume LUN to a Windows 2008R2 server. The volume is formatted with 64Kb NTFS blocksize In windows the Host Integration Toolkit is installed, and the rethinning option is scheduled regularly. Still after rethinning, the OS displays 260GB free space on the volume, but the EQL group manager displays only 90GB free space. There is a difference of 170GB between the two. Where is all the overhead going? Could the 64KB blocksize generate this much overhead into the backend? and how could i generate statistics or calculate the overhead? The number of files on the volume is 5548. So normal usage for this volume are large files. (on average 137Mb/file) Can anyone explain a little further into this?
Equallogic used space after rethinning differs in OS from EQL group view