From: Herbert Poetzl (herbert_at_13thfloor.at)
Date: Tue 17 Jun 2003 - 23:03:03 BST
On Tue, Jun 17, 2003 at 01:44:00PM -0500, John Goerzen wrote:
> Hi,
Hi John!
> I remember reading somewhere that when you run vserver with a RedHat
> installation, it can do "copy on write" hard links for binaries
> between one system and the next.
who told you that nonsense?
anyway, there is something called IMMUTABLE-LINK-INVERSION
which allows everyone (not only RedHat users ;) to save
disc space and, which usually is more interesting, memory.
to put it simple, there are two flags, one says, this file
can not be modified by anyone, not even root, the second
flag (which was introduced by Sam Vilain) says, but you
are allowed to remove it.
RPM based systems, have the 'advantage' that the contained
files can be easily categorized (config, binary, resource, ...)
so it wasn't to hard to implement this for RPM based
systems like Mandrake, SuSE and of course RedHat ...
> I have never used this feature since I'm running Debian. However, I'm
> interested in the mechanics, and I'm wondering if the system can,
> based on md5sums or some such metric, "combine" systems post-install.
it can be used, although it's not copy on write, as you
will know now ...
> If I knew the APIs, I'd be happy to write such a tool myself.
there where several proposals, and as far as I remember
Sam is actually maintaining (at least from time to time)
a tool to unify on debian and similar systems ...
best,
Herbert
> Thanks,
> John Goerzen