Re: [gentoo-user] Install Gentoo on one machine, then move the drive to another

[Alan McKinnon <alan@linuxholdings.co.za>]

On Wednesday 15 November 2006 18:15, Jon M wrote:
> Hey again everyone,
>
> Here is my situation:
>
> I have CentOS running on a system in a datacenter, but want to switch
> to Gentoo.  Basically what I've started to do is installed Gentoo on
> a P4 3.0Ghz machine at home, and plan on moving it to a Pentium D
> 2.66Ghz. Now if I configure/compile/install all my software on the
> P4, and the kernel is configured for all the hardware in the other
> machine, will it magically work, or will it freak out?  My other
> concern is that maybe the applications won't be optimized for the
> other machine.  If this is the case, once it's down there, could I
> simply emerge all of my programs one at a time?
>
> My reason for doing this is to minimize downtime.  I didn't want to
> take the server offline for a week while I take my time configuring a
> new setup.  This way it should only be down for maybe 5 minutes while
> I do a hard drive swap.
>
> Thanks in advance for anyones thoughts on this.

The one thing you *have* to do is configure the kernel on the compiling 
machine for the correct hardware that the date center machine has. 
There's no magic involved, when you boot into the new machine the 
driver for it's hardware is either there or it isn't.

You probably also want to set your CFLAGS to the lowest common 
denominator cpu - I don't recall off-hand what a Pentium D is, but I 
imagine the setting will be -march=pentium4. This will avoid the 
problem of code being compiled with cpu settings that are not present 
on the target system.

And don't worry too much about optimization. We have a word for that - 
it's called ricing and it's not a good thing. Compile the apps with 
sane settings and stuff works. Trying to eke out those last 4 cpu 
cycles just ain't worth the effort... If you need better performance, 
buy more RAM or faster disks

alan
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