Partitioning with gpart

[Thomas Mueller]

from "Lynn Steven Killingsworth" <blue.seahorse.syndicate at gmail.com>:

> I have installed PC-BSD 9.1 RC1 last week.  Very nice I must say.

> The default file system is zfs.  I have one storage disk which is ufs and
> another which is on an mbr partition.  I thought I would format the mbr
> disk with zfs and move everything from the ufs disk and then format the
> ufs disk with zfs.

> I have not tried the command line before so I just tried to create over
> the disk with: gpart create -s gpt ada2

> The message is that ada2 already exists as a file system.

> Show indicates that it is not gpt but mbr.

> Then in order to start over I tried to delete and destroy by starting with:

> gpart delete -i 1 ada2s1

> The message is that ada2s1 is an invalid argument.

> I cannot experiment on my backup as it has only one disk.

> Comment please?

Either gpt (included in FreeBSD prior to the switch to gpart) or gdisk (now at v0.8.5 and in FreeBSD ports) can migrate an MBR-partitioned disk to GPT without loss of data in many cases, though backing up is still advised.

You can find information about gdisk at
http://www.rodsbooks.com/gdisk/

gdisk is much more versatile than gpart, can be used to make partitions for Windows, Linux, NetBSD, etc.

I don't think you can get gpt for FreeBSD, but if you're curious, you can go to
http://www.netbsd.org/
and look for the documentation/man pages.

It was gpt in NetBSD that I used to migrate an NTFS partition (MBR) spanning an entire 3 TB Western Digital My Book USB 3.0 hard drive to GPT, no data was lost.

I subsequently booted Linux from the System Rescue CD (http://sysresccd.org/) and copied the software/data to a USB stick so I could free the USB 3.0 hard drive for better things.  Maybe I could have done the repartitioning with gdisk, which is included on the System Rescue CD, this would be Linux.

Tom