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woodypratt · Oct 8, 2008, 02:14 PM

I feel to determine this one takes the sector size and divide it by the sectors per cluster. But the number I get seems too high. Am I missing a step?

Scleros · Oct 8, 2008, 04:05 PM

If sector size = 512 Bytes,
and there are 8 sectors / cluster,
and 1024 Bytes = 1 KB, then...

Sector Size * Sectors / Cluster = (512) * (8) = 4096 Bytes / Cluster = 4 KB / Cluster.

woodypratt · Oct 8, 2008, 05:44 PM

thanks.. is there a tutorial on the web somewhere where I can learn a little more about this? Can one determine the Cluster Offset Value or FAT Table Entry or umber of Cluster(s) Required from this equation?

For # of clusters this is the equation that should work I feel (File Size / Sector Size = Number of Cluster ) ?

woodypratt · Oct 8, 2008, 06:38 PM

I think I GOT NUMBER OF Cluster (see my calculations)

Sector size * sector per cluster = cluster size

File size / Cluster size = number of cluster required

Scleros · Oct 8, 2008, 08:45 PM

Originally Posted by woodypratt

thanks..is there a tutorial on the web somewhere where I can learn a little more about this?

Try NTFS.com - Hard Disk Drive Basics, File Chaining and FAT Cluster Allocation, or Google for others.

Originally Posted by woodypratt

File size / Cluster size = number of cluster required ?

Yes, mostly. Some file systems have features that can consume space (clusters) above and beyond that needed for the actual file size; Windows NTFS Alternate Data Streams comes to mind.

woodypratt · Oct 9, 2008, 12:40 PM

so if you have those information of sector size, sector per cluser and cluster offset how can one get the value of the offset?

so from before I get that to get the cluster size one does Sector size * sector per cluster. To get the number of clustered required one does File size / Cluster size

but the offset value? This is what I am thinking
Cluster offset * sector size = cluster offset value (and need to change it to HEx)

Scleros · Oct 9, 2008, 03:00 PM

It's not that simple. You have to take into account the size of any data structures the particular file system itself uses. The NTFS.com site has a section on File Recovery that discusses some of this. This Clusters chain recovery for the deleted entry page gives an example of info needed for FAT starting cluster offset vs. NTFS.

What are you trying to do?