Linux – UUID and Drive Cloning

linuxmountpartitioningusbuuid

I have a project that I am working on, which involves a USB Storage Device and a boo.table version of linux. The way this project is coming together, I am having multiple partitions on the USB drive that need to be mounted at boot in order for proper resources to load.

My plan is to add the entries to the fstab using their UUID, however, I am not sure if this will work for my end goal. I currently have them mount by their label, but if a label is changed, the system fails to boot.

Eventually, when completed, this image will be cloned, and used to image a number of other USB devices.

My questions are these, when cloning a drive (using dd), will the UUID's for each partition change? Are they hardware specific? or does cloning it keep the same UUID as well? What happen if a system detected two devices with the same UUID?

Best Answer

UUIDs are not hardware-specific but stored in the partition's filesystem. That means cloning a disk or partition with dd will result in the same UUID.

You can assign a new UUID by using:

tune2fs -U random <device> (ext2/ext3/ext4)
xfs_admin -U generate <device> (xfs)
reiserfstune -u $(uuidgen) <device> (reiserfs)
mkswap -U $(uuidgen) <device> (swap)

Having duplicated UUIDs doesn't necessarily lead to errors. However booting and mounting a device by UUID will become ambiguous and may lead to the wrong device being used.

Related Solutions

Ubuntu Automount – How to Automount External Drive at Preconfigured Mount Point

GeorgeM is close, but not close enough.

On Ubuntu, gnome-mount is reponsible for mounting media and also for maintaining the needed configuration. The man page of gnome-mount should tell you much more and with a little trial and error you should be able to achieve what you want.

After I played with this for a little while, I found the following:

It seems you can not specifiy a mount point outside of /media
You can set the mount points name by hal udi

The following command will change the settings used to mount a USB drive on my system:

gnome-mount --write-settings \
            --hal-udi /org/freedesktop/Hal/devices/volume_uuid_00AD_15D0 
            --mount-point p

When inserted, the USB drive will be mounted in /media/p

Linux – LVM and cloning HDs

I agree with one of the previous answers -- running dd on the whole disk is not a great solution here. If the reason you're stuck on dd has to do with backing up another OS, then you can use dd only for those other OS partitions, and rsync for the linux partitions.

Part of the problem is that if you run dd of the whole disk while you have filesystems up and mounted from it, there is no way to ensure the backup is consistent. It may work 9 times out of 10, but under any load, the resultant backup could be corrupted. The only way to ensure this doesn't happen is to unmount all filesystems and deactivate all volume groups for the entire time that the dd is running. Not very convenient if your / is mounted from LVM.

In any event, if you insist on sticking with this approach, the tool you're looking for to rename a duplicated vg is called "vgimportclone". It's intended for use with device level snapshots, but it will work with dd as well.

Best Answer

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Ubuntu Automount – How to Automount External Drive at Preconfigured Mount Point

Linux – LVM and cloning HDs

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