Volumes and clusters

Waldermort · 07-03-2008, 10:12 AM

I wonder if anybody could help me out with this little problem I have been having.

As part of a defrag routine, I am iterating all the files on a volume and retrieving their LCN/VCN pairs with FSCTL_GET_RETRIEVEL_POINTERS. This all works well and good but the cluster counts are giving me a headache.

On a 15GB volume ( 0x003BFDFF clusters ) FileFsFullSizeInformation reports the number of used clusters being 0x001DA58C. This is a lot less than what I count while iterating the files ( 0x001EE4E5 ). Could it be that NTFS's sparse files are throwing this off? If so how can I correct it?

Adding further headache to the problem, I have run a count of the set bits within the volumes bitmap, here the used clusters is reported as being even less 0x001D7D4C. What is going on?

07-03-2008, 10:12 AM	#1
Waldermort Newbie Join Date: Feb 2008 Age: 28 Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts Rep Power: 0	Volumes and clusters I wonder if anybody could help me out with this little problem I have been having. As part of a defrag routine, I am iterating all the files on a volume and retrieving their LCN/VCN pairs with FSCTL_GET_RETRIEVEL_POINTERS. This all works well and good but the cluster counts are giving me a headache. On a 15GB volume ( 0x003BFDFF clusters ) FileFsFullSizeInformation reports the number of used clusters being 0x001DA58C. This is a lot less than what I count while iterating the files ( 0x001EE4E5 ). Could it be that NTFS's sparse files are throwing this off? If so how can I correct it? Adding further headache to the problem, I have run a count of the set bits within the volumes bitmap, here the used clusters is reported as being even less 0x001D7D4C. What is going on?

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