Subject: Re: [vserver] Pros and Cons of 32/64bit guests on 64bit host
From: Chuck <chuck@sbbsnet.net>
Date: Wed, 20 Aug 2008 18:41:01 -0400

On Wednesday 20 August 2008, Cedric Veilleux wrote:
> Hi,
> 
> > As I have to update the guests anyway (I used and will use gentoo for
> > them), so I am considering to move them to 64bit, too. The guests are
> > several LAMP servers, mysql and postgres and a set of qmail nodes.
> > 
> > The only issue that is an obvious go for 64bit would be memory segments
> > >3GB, but I guess I wont have guests who use it. So, anybody here can
> > give pros and cons for 32/64 bit guests?
> 
> I recently did pretty much the same thing, migrate a bunch of 32 bit
> guests to new 64 bit based hosts and it went very well.
> 
> 32 bit guest will be just as stable in a 64 bit host than in a 32 bit
> one. So stability is not a problem.
> 
> Other than that, you are already aware of the memory limit advantage of
> 64 bit guests.. not really useful for most guests indeed..
> 
> The last advantage of 64 bit is performance, some applications will
> perform better in 64 bit (while others seem to do worse).. For LAMP /
> QMail, I doubt there is a big speed difference.. Anybody can confirm
> that?
> 

when i converted our qmail system over, there was a noticable difference but i 
dont believe it was due to 64bit. qmail itself executed a bit faster due to 
better hardware,but there was a very noticable difference in executing the 
spam and anti-virus portions so in general the entire server was faster. so i 
think 64bit had some helping hand in this but how much i am not sure.


> If you are just migrating an existing 32 bit guest, converting it to 64
> bit will be a lot of work, as there is essentially no distribution that
> supports such upgrade path (AFAIK)...
> 

it is a bit of work. i created a fresh 64bit guest, installed all packages 
then moved the configs and data over. was more time consuming to make sure i 
got everything than difficult.

> Personnaly, I am slowly phasing out 32 bit guests in favor of 64 bit
> ones, but the conversion to 64 bit is never the real reason behind the
> move. It just seems logical to me to create new vservers as 64 bit and
> keep the old ones in 32 bit until there is a real reason to upgrade
> them.
> 
> 
> Cedric
> 



-- 

Chuck