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In short, I want to create a system restore image. My idea with AUFS is like the image belowAUFS union root

Now, as I require this mount setup at boot-time, I don't think I can do it with fuse and will require AUFS kernel support, which, CentOS 6.x doesn't have. So I started to think along an alternative approach with LVM snapshots. The setup I have in mind is like following imageLVM snapshot mount

However, I have a few questions about this setup.

  1. Is this kind of setup at all possible with LVM or device mapper? If yes, how to do it?
  2. with LVM, is it guaranteed to have write-protection in physical volume for read-only snapshots?

Thanks in advance.

Samik
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  • [Yes.](http://developerblog.redhat.com/2014/09/30/overview-storage-scalability-docker/) – Michael Hampton Feb 20 '15 at 21:35
  • @MichaelHampton, the article you've linked to elaborates on how to implement a CoW docker backend. How do I do it with a physical machine, i.e. if I want the machine to boot with the aforesaid mount setup? – Samik Feb 21 '15 at 05:48
  • I don't see why not. Though you're probably reinventing the wheel. Look into [atomic updates](http://www.projectatomic.io/docs/os-updates/), for instance. – Michael Hampton Feb 21 '15 at 05:56
  • @MichaelHampton, as you've pointed out, this setup seems possible. I've tested this kind of setup with device-mapper snapshot target but with files loop-mounted as block device and on some non-root (e.g. `/mnt/dm_mount` rather than `/` itself) mount point. I can't figure out how to do it in boot-time and with `/` mount point. Can you please post an answer for that? – Samik Feb 22 '15 at 08:23

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