NTFS file system 2 Terrabyte partition size limit

I’ve been seeing this issue a lot on RAID capable systems now that 1.5 and 2 TB drives are cheap and people want larger and larger RAID Arrays.  In essence, partition sizes are limited to 2 TB.  This is a NTFS file system limitation, so it isn’t just a 32 bit Windows issue.  Technical stuff below:

On an MBR (Master Boot Record) disk, the locations where the partition sizes are stored are only 4 bytes long.  Since this is in hexadecimal, the largest value we can stuff in there is all F’s.  So the max value would 4,294,967,295 in decimal. 

FF FF FF FFh = 4294967295d

This maximum partition size is not in bytes, it is in number of sectors.  Since currently sectors are limited to 512 bytes, the maximum size ends up being 2 TB.

4,294,967,295 sectors * 512 bytes/sectors = 2,199,023,255,040 bytes or 2TB.

Reference:  http://blogs.technet.com/askcore/archive/2010/02/18/understanding-the-2-tb-limit-in-windows-storage.aspx