Hi, I am installing windows 10 on an old windows 8.1 notebook (from the era before the bios had UEFI or legacy mode options), so windows gives me an error about unable to install as the drive needs to be formatted in GPT drive format not MBR.
Is there any way to convert an existing drive to GPT format without wiping all the data (almost 2TB) so I can install windows 10?
No. You have 2 options when formatting a LARGE drive. Up to 2.1 terrabyte can be formatted as MBR, Windows computers wont see more than 2.1tb no matter how big the drive is if formatted to MBR. If formatted to GPT, you can then see ALL available disk space. If your drive is formatted to MBR, then you are pretty much screwed.
there are tools that CLAIM to be able to do this non-destructively, my experience has been otherwise. My suggestion, boot with a PE Rescue Disk (hirens works well) and backup everything you want saved onto multiple flash drives, then format the drive and start from scratch. If you want to try to convert the drive, here is a tool that may work for you.
Convert MBR to GPT without data loss using Gptgen
You can convert MBR to GPT without losing data – using a command line utility called
gptgen. Gptgen is a tool designed to non-destructively convert hard disks partitioned in the common, “MSDOS-style” MBR scheme (including extended partitions) to use a GUID partition table (GPT).
It’s a very extensive tool but a bit complicated to run. According to the tool’s ‘read me’ file, the syntax of the tool is “
gptgen [-w] \\.\physicaldriveX”, where X is the drive number reported by the Disk Management console or the “
list disk” command of the
DISKPART utility. The
-w switch makes gptgen write the generated GUID partition tables to the disk – otherwise, the primary table will be written to a file named “
primary.img“, and the secondary table to “
secondary.img“, in the directory that the program was invoked from. You can then use
dd to write the tables to the disk.
