UUID

[Michael Havens]

better yet could someone come explain it to us:
http://www.bleepingcomputer.com/forums/t/561405/new-partition-scheme/page-2#entry3582631

:-)~MIKE~(-:

On Tue, Dec 30, 2014 at 7:38 PM, Michael Havens <bmike1 at gmail.com> wrote:

> I'm part of another discussion in which we are talking about UUIDs.
> This is what one of the participants said:
>
> As pointed out earlier by bmike1 in response to my comment about GRUB2 not
> being able to find the OS if you move the partitions, by default on Linux
> Mint GRUB2 will use UUIDs *(the id tag for your partitions)* instead of
> partition numbers*(eg: sda1, sda2, etc)*, so I was incorrect when I said
> GRUB2 won't be able to find the boot partition. Linux Mint's fstab *(a
> config file read at boot to tell Mint which partitions should be
> automatically mounted)* also uses UUIDs by default so no issues there.
> Therefore I do not see any reason why moving your installation would be an
> issue *(keep reading)*, so I decided to test it in a virtual machine. I
> installed Linux Mint 17.1 - Cinnamon 64bit *(I've been wanting to try
> Linux Mint for a while. I've been downloading a little bit of the ISO each
> day)* with a partition layout similar to yours *(http://i.imgur.com/3qg0bSv.png
> <http://i.imgur.com/3qg0bSv.png> )*. I wasn't able to move the extended
> partition using Gparted, or create a new one. In the end I just created 3
> new primary partitions and cloned the Linux Mint logical partitions to them
> using dd *(dd is a sector based cloning tool that comes pre-installed on
> most Linux operating systems. I used it because this way the new partitions
> will have the same UUIDS as the Linux Mint ones did. This is important
> since GRUB2 is using UUIDS to identify the boot partition and because the
> fstab uses UUIDs to identify your swap partition)*. Then I deleted the
> old partitions *( http://i.imgur.com/hDBT5ns.png
> <http://i.imgur.com/hDBT5ns.png> )*. The result was that GRUB2 was unable
> boot Linux Mint because it couldn't find the boot partition *(I don't
> know why this is, but if I had to take a guess it would be that GRUB2 was
> probably storing part of itself on the extended partition's VBR which no
> longer exists because I deleted the extended partition)*. So GRUB2 needed
> to be repaired. Using a Linux Mint Live-cd, I ran "sudo
> add-apt-repository ppa:yannubuntu/boot-repair"*(this adds a third party
> repo that has boot-repair in it, because it's not available in the default
> Linux Mint repos)*, "sudo apt-get update" *(to update apts package list)*,
> "sudo apt-get install boot-repair" *(to download and install boot-repair)*,
> and then I ran boot-repair with its default settings *(be warned by
> default boot-repair uploads information about your computer online, you can
> disable this)*. This successfully fixed GRUB2, and I was able to boot
> Linux Mint again *(http://i.imgur.com/ZJhXRbe.png
> <http://i.imgur.com/ZJhXRbe.png> )*.
>
> I then said:
>
> I think I know why it needed repairing. The reason is that you created new
> partitions (new UUIDs) and deleted the old partitions (the existing UUIDs).
>
> to which he responded:
>
> The partitions were cloned with dd so that they would have the same UUIDs.
> I also used "sudo blkid" to verify the uuids of the new primary partitions
> matched before deleting the original logical partitions.
>
> He and I both remarked between the first and last quote that we thought
> the UUID of the partition would of had it recognized regardless of what we
> did with other partitions on the drive. Could someone kindly explain to us
> wherein the difficulties lie?
> :-)~MIKE~(-:
>
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