Non-destructive MBR to GPT conversion

[Eric Sauve]

I have a NAS (Proliant DL185) running WIndows Storage Server 2003 R2 with a 1.7 TB partition that I would like to add about 1.2 TB to it but since the partition is MBR based, I'll need to make it a GPT based partition in order for it to address the whole 2.9 TB. Is there a partition manager software that will let me convert from an MBR to an GPT partition non-destructively?