Upgrade from 32-bit to AMD-64?

[Bakul Shah]

On Thu, 12 Feb 2009 21:01:38 CST Karl Denninger <karl at denninger.net>  wrote:
> >> I guess I need to schedule the 2-3 hours of downtime..... the reason for
> >> this, by the way, is that I have a dbms app on there that is getting too
> >> RAM hungry for its own good (its a Quadcore CPU) and I'm up against the
> >> RAM limit for 32-bit code.  The board will support more but 32-bit code
> >> won't; ergo, the only way to get beyond this is to go to 64-bit.
> >>     
> >
> > Oh wait!  One thing you wanted to know is that, some database *can* have
> > different on-disk format for 32-bit and 64-bit binaries.  Be sure to
> > have a dump handy.  Last time I hit this on a MySQL "upgrade" between
> > two servers, and I end up using its replication functionality.  The
> > operation took longer time than I expected at the beginning.
> >
> > My personal suggestion is that you do an experiment on another box
> > (64-bit capable) to make sure that the data would work, this never hurts
> > and avoids surprises (you do want 64-bit compile of your database
> > application since you want to take full advantage of 64-bit OS); also,
> > just like all upgrades, full backup is advised.
> >
> > Cheers,
> > - --
> > Xin LI <delphij at delphij.net>	http://www.delphij.net
> I already know I have to dump the database and then reload it - I 
> attempted to migrate the disk structure across (which would have saved 
> even more time) and got instantaneously hosed, presumably due to 
> internal data type length differences.
> 
> This little upgrade is going to take a while; sounds like the best 
> approach is to load a new box, shut down the dbms to connections and 
> dump/pipe it over, then physically swap the machines.

May be you can install the 64 bit world from an install CD to
a 2 to 4GB USB flash drive, reboot to the 64 bit kernel & set
root on the flash drive, mount your original filesystems
under /mnt, make and install with DESTDIR=/mnt, mergemaster
-D /mnt and reboot?