[CentOS] Question about storage for virtualisation

Mon Jul 2 18:42:15 UTC 2012
Stephen Harris <lists at spuddy.org>

On Mon, Jul 02, 2012 at 01:18:58PM -0500, Les Mikesell wrote:
> You aren't done booting until you complete the init scripts for
> runlevel 1.  Having to have an extra copy of the kernel on yet another
> device to even get started seems wrong from a minimalist approach, and

There's no extra kernel image needed.  Kernel comes from /boot, just as
today.  You need to copy a few modules into the ramdisk so that drivers
can be initialised, and you need a few user-space utilities (on RedHat 5
these are mostly provided by "nash"; RedHat 6 is a lot more detailed in
the initramfs image).

> the need for sufficient ram for an initrd even more so.  And you

Yes, this is one downside to the proposal; you can't have a separate
/usr partition on RAM limited machines (with RedHat you need, maybe, 4Mb
of RAM for the initrd; with RedHat 6 that is gone up a lot).  The
memory should be free'd back once the switch to real-root has been made
so it's temporary but, yes, it is a requirement if you want separate
/ and /usr partitions.

But, equally, these are likely to be storage limited machines as well (e.g
embedded devices) so aren't likely to want to waste space on partioning
losses or will be using nfsroot, so this edge case isn't a likely case.

And if you _do_ have this pathological edge case then you don't have to
follow the Fedora standard; you're gonna be going your own way, anyway!

> really should be able to mount /usr via nfs while retaining
> independent boot/diagnostic capability.

You can.  Nothing in this proposal stops this.

> What's the problem with just following $PATH?

I've no idea.  It's not my proposal.  I don't see the _need_ to do it;
indeed I said that most people will still set PATH to include bin and
usr/bin simply 'cos of cross-OS compatibility (AIX, HPUX, other Linuxen

I'm just saying that I don't see it causing any true pain.