[lxc-devel] [PATCH] implement loopback backing store

[Tomas Pospisek]

Am 03.06.2013 23:38, schrieb Serge Hallyn:
> Create a loopfile backed container by doing:
> 
> 	lxc-create -B loop -t template -n name
> 
> or
> 
> 	lxc-clone -B loop -o dir1 -n loop1
> 
> The rootfs in the configuration file will be
> 
> 	loop:/var/lib/lxc/loop1/rootdev

While I applaud usability improvements, I am not sure VMs in a loopback
device should be promoted.

It's known that the loopback device can deadlock and loose data
[1][2][3], which I find highly problematic.

It happened many times to us, the problem has been known for many many
years, but no fix or workaround exists as far as I'm aware and it
doesn't seem anybody is making efforts to fix this.

If this functionality is to be shipped, then I'd strongly advise to ship
a *fat* warning in the documentation and also when creating such a VM
instance that says:

  "having your FS run on a loopback device can destroy all your data"

*t

[1] http://www.gossamer-threads.com/lists/drbd/users/8688#8688
[2] http://www.drbd.org/users-guide/ch-configure.html#s-prepare-storage
[3] http://lists.linbit.com/pipermail/drbd-user/2011-May/016009.html