Subject: Re: [vserver] 32bit Guests on 64bit Host
From: Ed W <lists@wildgooses.com>
Date: Mon, 21 Dec 2009 14:29:42 +0000

On 21/12/2009 14:17, Ghislain wrote:
>    
>> My observation was that the 64bit vservers (nginx + fastcgi PHP)
>> appeared to use quite a bit more RSS and LOTS more VSS (not sure how
>> much this actually matters though?). I found it workable, but being on
>> a rented server the available ram is quite precious and it was a tough
>> call to move over to fully 64bit.  Previously I have used a 32bit
>> apache + modphp setup and not noticed any issues either (I find nginx
>> quite a bit easier to manage and much lighter on ram, so largely I
>> have switched)
>>      
>
> yes 64bit guest seems to have high memory in the VSZ. My little guest
> here are 500 RSS but in vserver-stat shows up with 4.8GB of VSZ each :)
>
>    

 From memory my 64bit guests showed 4x the VSZ of the 32bit version of 
the same (pretty much a direct port of one to the other)

Actually, also my little trick is to make all the "data", eg /var mount 
from a separate dir which I keep away from the main vserver instance.  
So my instances are kept in /vserver/images/www123 and the data in 
/vserver/shared/www123

The point of this is that if you want to clone an instance to test an 
update say, you don't need to clone all the big data files and if 
required you can simply mount the live data onto the new instance (be 
careful) to test.  I don't split out the /etc/ because it seems hard to 
re-use this across instances, but I do back it up and use gentoo 
overlays to get some of the key files roughly consistent.  I use an 
rsync style backup (snapback2) and I can use different schedules for the 
relatively small OS images compared with the large data files

I'm sure others are splitting up their OS partitions even smaller than 
this since it's just 101 unix admin stuff, but I think it's easy to 
forget these basic skills when faced with virtualisation?

Good luck

Ed W