Comparing current GPT partition table against a backup

mailtomsa · 01-29-2016, 01:27 PM

Hello,

I have a GPT partition table backup/dump that I created using "sgdisk -b".

My "live" partition table seems to have changed (the Windows system of my dual boot is no longer booting) and I would like to somehow look at what is different between the backup and the "live" partition tables.

Can I do that? Or is there something to display the content of the binary backup file in a more human-readable format, something similar to what gdisk's "p" ("print the partition table") command does?

Thank you!

dijetlo · 02-01-2016, 05:46 PM

You could print the detail of the current gpt configuration using the "-i" switch, back the current partition data up using the "-b" switch and then load the previous backed up partition data using the "-l" switch. If you then run "-i" again to get the original detail you'd be able to compare the two. You could then restore the last backup of the partition data.
Of course, I'd be sure to do a full back up (or perhaps a disk image) and be ready to reinstall both OS's before I started that process in case something went awry.

syg00 · 02-01-2016, 06:14 PM

Quote:

Originally Posted by mailtomsa

My "live" partition table seems to have changed (the Windows system of my dual boot is no longer booting)

Do you have any reason to make this association ?. Pretty tenuous I would reckon.

I'm surprised Rod hasn't a tool to do this - maybe try loop mounting the file and simply run gdisk against that

mailtomsa · 02-01-2016, 06:52 PM

Quote:

Originally Posted by syg00

Do you have any reason to make this association ?. Pretty tenuous I would reckon.

Well, it's mostly that I want to verify if and what changed in the partition tables (probably just a partition type marker) before I restore the backup in order to make sure that restoring the backup makes sense and fixes my problem before I risk messing up even more if something goes wrong with restoring the backup.

I was thinking about a loop device as well (trying to set up a small size loop device and restoring the backup into that), but have not tried it yet...

mailtomsa · 02-03-2016, 02:29 AM

Oooops... I just tried

Code:

gdisk -l <my_backup_file>

and it displayed the partitions from the backup file just the way

Code:

gdisk -l /dev/sda

would.

Who would have thought it's that easy...

syg00 · 02-03-2016, 02:46 AM

Who'd thunked. +1 for Rod.

I tested the loop mount, that worked too.