Subject: Re: [vserver] 32bit Guests on 64bit Host
From: Ed W <lists@wildgooses.com>
Date: Mon, 21 Dec 2009 12:04:30 +0000
Mon, 21 Dec 2009 12:04:30 +0000
On 21/12/2009 04:37, Ghislain wrote:
> Le 20/12/2009 14:56, Herbert Poetzl a écrit :
> > On Sun, Dec 20, 2009 at 01:25:04PM
> +0100, Oliver Welter wrote:
>> Hi All,
>>
>> anybody can tell me, if there are drawbacks/issues, running 32bit
>> systems on top of a 64bit host?
>>
>> > there should be none as long as the personality is set
>> > properly and you have the 32bit compatibility enabled
>>
>
> note that we use mixed guest host and we have no major issue apart 
> from an heavely used web server that see quite a lot of segfault in 
> php. Personality is set to PER LINUX32 but that still bring  issues. 
> However this this the only case of issues i have (it is on 
> 2.6.31.3-vs2.3.0.36.18 ,  util-vserver: 0.30.216-pre2849). The very 
> same web cluster has one system with 64bit guest that do not segfault 
> at all. Setting the personality on the 32bit system removed a lot of 
> them but i still get 4 per week per server at least.
>

I use gentoo 32bit hosts on some of my vservers.  Actually, to moderate 
that a bit, I think right now I need to say "I *did* use..", I think 
they all switched to 64bit now? (Need to check)

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)

Certainly I never noticed a speedup/slowdown (no benchmarks done, just 
observing by eye).  Also I never saw any segfaults either 32bit/64bit - 
I might not be watching closely enough, but I just run a basic fastcgi 
cluster and it stays up for a year or so before random fluctuations 
cause a reboot - not especially heavily loaded server though, from 
memory it does much less than a million hits a month (probably quite a 
lot less, can't even remember when I last looked at the stats...)

I can roughly say that I notice no difference between 32bit and 64bit 
for basic web/email usage...  My migration was from a 32bit server to a 
64bit vserver host and then gradually migrating the vservers 1 by 1 to 
64bit.  I also used someone else's advice and swapped to making my own 
base template servers and more recently also my own gentoo profiles and 
this means I can very quickly spin up a new server, binary packages used 
almost everywhere and the custom profiles ensure it's fast to install a 
consistent suite of software across all similar types of server

Very pleased with the end result

Good luck

Ed W




On 21/12/2009 04:37, Ghislain wrote:
Le 20/12/2009 14:56, Herbert Poetzl a écrit :
> On Sun, Dec 20, 2009 at 01:25:04PM
+0100, Oliver Welter wrote:

Hi All,

anybody can tell me, if there are drawbacks/issues, running 32bit
systems on top of a 64bit host?

> there should be none as long as the personality is set
> properly and you have the 32bit compatibility enabled

 
note that we use mixed guest host and we have no major issue apart from an heavely used web server that see quite a lot of segfault in php. Personality is set to PER_LINUX32 but that still bring  issues. However this this the only case of issues i have (it is on 2.6.31.3-vs2.3.0.36.18 ,  util-vserver: 0.30.216-pre2849). The very same web cluster has one system with 64bit guest that do not segfault at all. Setting the personality on the 32bit system removed a lot of them but i still get 4 per week per server at least.


I use gentoo 32bit hosts on some of my vservers.  Actually, to moderate that a bit, I think right now I need to say "I *did* use..", I think they all switched to 64bit now? (Need to check)

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)

Certainly I never noticed a speedup/slowdown (no benchmarks done, just observing by eye).  Also I never saw any segfaults either 32bit/64bit - I might not be watching closely enough, but I just run a basic fastcgi cluster and it stays up for a year or so before random fluctuations cause a reboot - not especially heavily loaded server though, from memory it does much less than a million hits a month (probably quite a lot less, can't even remember when I last looked at the stats...)

I can roughly say that I notice no difference between 32bit and 64bit for basic web/email usage...  My migration was from a 32bit server to a 64bit vserver host and then gradually migrating the vservers 1 by 1 to 64bit.  I also used someone else's advice and swapped to making my own base template servers and more recently also my own gentoo profiles and this means I can very quickly spin up a new server, binary packages used almost everywhere and the custom profiles ensure it's fast to install a consistent suite of software across all similar types of server

Very pleased with the end result

Good luck

Ed W