[CentOS] MIgrate/Upgrade from Centos 5.4 32bit to Centos 5.4 64bit

Robert Heller heller at deepsoft.com
Tue Jan 5 20:09:23 UTC 2010


At Tue, 5 Jan 2010 11:26:32 -0800 CentOS mailing list <centos at centos.org> wrote:

> 
> On Tue, Jan 5, 2010 at 11:24 AM, MHR <mhullrich at gmail.com> wrote:
> > On Tue, Jan 5, 2010 at 7:46 AM, Oliver Schulze L. <oliver at samera.com.py> wrote:
> >> Hi,
> >> It is posible to do a simple procedure to upgrade a Centos 5.4 32bits
> >> (i686) to
> >> a Centos 5.4 64bits(x32_64)?
> >>
> >> I was thinking about an upgrade or install without formating.
> >>
> >> I will have a current backup before doing it.
> >>
> >> Any advice/tips is welcome.
> >>
> >
> > I *strongly* doubt it.  When you go from 32 to 64 bit systems, you are
> > essentially replacing the kernel and (at least) about 90% of the
> > standard libraries.  I am willing to bet that this mandates an
> > installation.
> >
> > For the record, I've never tried it.  When I put CentOS on my machine,
> > I already had a 64-bit CPU and I never seriously considered NOT using
> > the 64-bit install.
> >
> > HTH.
> >
> > mhr
> >
> 
> Sorry - PS:  IIRC, you don't _have_ to format your disks to install
> over what's on them - check the installation options when you get that
> far and read through them carefully.  You should be able to re-use
> existing partitions, but I can't remember whether that *requires*
> reformatting them - I've just always done that (reformat them).

You really should/ought to reformat /, /usr, and /var.  /boot and /home
don't need to be reformated (leaving /boot alone allows for multi-OS
version booting, eg CentOS 4 and CentOS 5 or Ubuntu and CentOS or CentOS
and Fedora, etc.).  The installer will be unhappy about NOT reformatting
/, /usr, or /var.  It will warn about not reformatting /boot -- this is
generally OK though.  It will NOT complain about not reformatting /home
or any other random non-system file system you might have (I do things
like have a dedicated /mp3s file system on my laptop for example).

Unlike the *default* file system setup, which only creates /boot and /
file systems, it is *strongly* recomended to instead create separate
/boot, /, and /home file systems (at least these three -- separating
out /usr and/or /var might make sense under some situations, esp.
servers) -- this allows updates, multi-OS, and recovery without having
to make an explicit backup (although, having backups is still
recomended!).

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>                                                                                                                      

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Robert Heller             -- 978-544-6933
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