[gentoo-user] Replace root with aufs-united sda & squashfs

[gentoo-user] Replace root with aufs-united sda & squashfs

[Pandu Poluan]

As part of Project:Protogenoi [1], I am planning to replace root with
a united filesystem using aufs. The layers will be:

Top: /dev/xvda3 (Xen/XenServer Virtual Disk device)
Bottom: /.root.sqfs

The aim would be to generate the smallest .xva (XenServer Virtual
Appliance) possible. To achieve this, the 'physical root' at /dev/sda3
will be emptied as empty as possible, except for /etc and /dev.

AFAIK, there are files that *must* still exist for this strategy to
succeed. However, this post from f.g.o [2] said that those files
aren't necessary. So, I should do the following sequence in /etc/fstab
:

1. Mount /dev/xvda3 as /
2. Mount /.root.sqfs as /
3. Mount aufs, uniting /dev/xvda3 and /.root.sqfs as /
4. Mount everything else

Am I getting this right?

[1] http://en.gentoo-wiki.com/wiki/User:Pepoluan/Project:Protogenoi
[2] http://forums.gentoo.org/viewtopic-p-5707187.html?sid=b8feb20174c9d8d9ae74fc82a30ce911#5707187


Rgds,


-- 
--
Pandu E Poluan - IT Optimizer
My website: http://pandu.poluan.info/

[gentoo-user] Re: Replace root with aufs-united sda & squashfs

[Nicolas Sebrecht]

On Sat, Jul 23, 2011 at 11:01:43AM +0700, Pandu Poluan wrote:

> AFAIK, there are files that *must* still exist for this strategy to
> succeed. However, this post from f.g.o [2] said that those files
> aren't necessary. So, I should do the following sequence in /etc/fstab
> :
> 
> 1. Mount /dev/xvda3 as /
> 2. Mount /.root.sqfs as /
> 3. Mount aufs, uniting /dev/xvda3 and /.root.sqfs as /
> 4. Mount everything else

AFAIK, it should be more something like:

  mount -t aufs "/dev/xvda3(rw) and /root/sqfs(ro)" /new_root

And then chroot to /new_root.

-- 
Nicolas Sebrecht