Re: Advice in switching from Mandriva 64 to Debian 64
On Thu, 20 Oct 2005, Jean-Jacques de Jong wrote:
Hi,
I am planning to switch to Debian from Mandriva. I have an AMD64 and I would
like to exploit the 64 bits for those programs that really need it (video
editing/transcoding, photo editing), and still run Firefox with Flash,
OpenOffice, and Wine (CodeWeavers and Cedega).
The issue is that the 32 bit applications need to be run by the rest of the
family, and I fear a chroot environment would be too complex for them (they
just want to click on an icon and it must work).
They don't need to be aware of the chroot for it to work, if it's configured
properly. I have a similar setup and my users usually have no indication
but just run what they want. This is how I did it:
1) install the 64 bit system first, with everything you want in there.
2) create a chroot, following the howto in the debian documentation,
including bind mounts and the sort, so that home directories, X etc. are
indeed available in the chroot.
3) compare the passwd, shadow, group and gshadow files in the 64 and
32 bit sides, make sure to make them as nearly equal as you can.
4) get the list of installed packages in the 64 bit system, e.g. with
dpkg --get-selections >my64bitselects
5) install the same packages in the 32 bit chroot, e.g. with
dpkg --set-selections <my64bitselects (run this in the chroot)
6) fire up dselect (or whatever your favourite package manager is) in
the chroot, to make sure there are no conflicts, resolve them if needed
and install the needed packages. This will waste a lot of disk space,
but you will gain 64 and 32 bit sides which are almost exact mirrors,
making sure that Joe User can just run anything, be it in 64 or 32 bit
space, in exactly the same way, and it will just work.
7) most boring step: review all configurations in the 64 and 32 bit
sides, make sure they are as consistent as you can make them
8) in the 64 bit side, configure something as dchroot or schroot so
that your users can run programs in the 32 bit chroot, and create
scripts in /usr/local/bin for those programs you want to run in the
chroot (e.g. firefox, mozilla, OOo, acroread...) and arrange the
default path to look in /usr/local/bin _before_ /usr/bin. In this
way, you can just type the command and, if you arranged for a
script to be run in /usr/local/bin, it will take precedence over the
64 bit app, even if it is present, unless you call the latter with
the full path (which you usually don't do).
9) possibly arrange a few default icons in the desktops of your users,
so that they will run either the scripts you prepared or directly the
32 bit programs in the chroot.
All of this is a bit of a PITA to set up and requires some maintenance
(you have to be careful to keep system configurations consistent between
64 and 32 bit sides when you upgrade something), but it is very
effective. I have yet to hear a complaint from my users, and I maintain
a cluster of 9 amd64 computers in my institute all set up this way.
In every single case in which I migrated a user from 32 to 64 bits,
they were stunned by the performance gain and did not notice problems
(because I had taken care of them in the above way). We have plenty of
legacy (commercial) 32 bit data analysis software.
Be patient, if you embark on this, it will take some work.
Bye
Giacomo
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Giacomo Mulas <gmulas@ca.astro.it>
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OSSERVATORIO ASTRONOMICO DI CAGLIARI
Str. 54, Loc. Poggio dei Pini * 09012 Capoterra (CA)
Tel. (OAC): +39 070 71180 248 Fax : +39 070 71180 222
Tel. (UNICA): +39 070 675 4916
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"When the storms are raging around you, stay right where you are"
(Freddy Mercury)
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