Arch Linux

fabfour

Member

Registered: 2011-11-02

Posts: 4

New to LVM Snapshots - Is this possible?

Hi,

as far as I understood snapshort are not persistent over a reboot. That means i cannot shutdown and unmount a partition and its snapshot and remount it after reboot. Is that correct?

I want to use snapshots, to create a test system which is persistent over reboot. Could this be a possibility to circumnavigate this?

Add a new Startup Option to Grub (Something like boot test configuration)

Create a hook in Initrd which reads cmdline an a flag like "bootsnapshot"

Then
If there is nothing in snapshot partition -> create a new snapshot and boot into it instead of real root
If there is a snapshot in partition -> boot into it

After a while and some bootups i can trigger a merge and write the changes to real root or discard the changes.

Would this work?

Thanks for your opinion

Spider.007

Member

Registered: 2004-06-20

Posts: 1,176

Re: New to LVM Snapshots - Is this possible?

Hi,

as far as I understood snapshort are not persistent over a reboot. That means i cannot shutdown and unmount a partition and its snapshot and remount it after reboot. Is that correct?

No, where did you read this?

[...] Would this work?

This could be done, but maybe you can describe what your intentions are as there are many alternative methods of doing this; such as using onionfs to mount a tmpfs over your existing root. Why do you want to do this?

fabfour

Member

Registered: 2011-11-02

Posts: 4

Re: New to LVM Snapshots - Is this possible?

Thanks,

i want to have the possibility of rollback after a system upgrade. Thats my primary intention.

Are there better ways?

lucke

Member

From: Poland

Registered: 2004-11-30

Posts: 4,019

Re: New to LVM Snapshots - Is this possible?

Have a look at http://www.nikhef.nl/~dennisvd/lvmcrap.html.