Re: Testing Jessie in a chroot?

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I am still running Wheezy and would like to test Jessie before committing to
> it.  Is a chroot a viable method?  If so, can someone point me to a link on
> how best to set it up and use it.  I will want to test it with, and without,
> systemd.  Would a dual boot be a better way to test this?

Given the recent discussion about LVM, here's how I've done it recently:

- create new LVM volume to hold a backup of the current system.
  I typically have a "root" LVM volume which holds the OS, and I make
  the backup volume as a snapshot (so the copying is done lazily):

   lvcreate --name wheezy --size 10G --snapshot /dev/mapper/<My-VG>-root

  [ The size can be smaller than that of "root" (it will only need to
  hold those chunks which are modified), but if you have enough space,
  I recommend you make the size just as large as "root" to avoid
  losing/corrupting this snapshot if you end up writing more chunks than
  expected.  ]

- perform the upgrade.

- whenever you want/need to look at or use the older system, you can
  either mount /dev/mapper/<My-VG>-wheezy (and maybe chroot into it), or
  reboot into it (at the Grub prompt, edit the "linux" line so that it
  uses "root=/dev/mapper/<My-VG>-wheezy").

- if you just want to revert to the original state, you can use
  "lvconvert --merge /dev/mapper/<My-VG>-wheezy".


        Stefan