Re: from / to /usr/: a summary
On Sun, Dec 25, 2011 at 04:12:48PM +0800, Thomas Goirand wrote:
> On 12/22/2011 07:07 PM, Russell Coker wrote:
> > It seems to me that wanting to have / outside LVM but /usr inside LVM is a
> > fairly obscure corner case.
> I have about 100 servers setup this way, and my laptops as well. I really
> don't see why this would be a corner case. Please understand that many
> different people have many different configuration, and that in today's
> Debian, *absolutely everything is allowed*, and never, ever, Debian said
> that one type of setup would one day be forbidden.
Several years ago, it used to be the case that a combination of
bootloader support and/or initramfs support meant that it was
not possible to have / on LVM. Nowadays, it's possible to have
the rootfs on LVM on MD raid, and the bootloader and initramfs
are perfectly capable of setting things up properly.
While it's still possible to set up a system the "old way", today
this is sub-optimal and definitely not to be recommended. For
example, on the laptop I'm writing this on:
% mount | grep mapper
/dev/mapper/sysvg-root on / type ext3 (rw,relatime,user_xattr,errors=remount-ro,commit=0)
/dev/mapper/sysvg-usr on /usr type ext3 (rw,relatime,user_xattr,commit=0)
/dev/mapper/sysvg-var on /var type ext3 (rw,relatime,user_xattr,commit=0)
/dev/mapper/sysvg-home on /home type ext4 (rw,relatime,user_xattr,commit=0)
I used to use exactly the setup you are using. But for all the
systems I've installed in the last few years, there was no point--
everything including swap can just go into an LVM VG. On more recent
systems, I also omit the separate /usr given that it's effectively
pointless.
Regarding it being a corner case, this is I think true. It's no
longer a recommended setup. While obviously this will necessarily
continue to be supported for now and for a good while yet, it might
not be in the distant future. Regarding "absolutely everything is
allowed", this is not really true. At some point some things do
need retiring (I'm not saying this is true for the above, yet) when
there are obviously better ways of accomplishing the same thing.
Regards,
Roger
--
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