[CentOS-virt] i386 VM on x86_64 host in Xen

Tue Dec 11 15:53:26 UTC 2007
Scott Dowdle <dowdle at montanalinux.org>


----- "Christopher G. Stach II" <cgs at ldsys.net> wrote:
> It would really suck to have 3795 "virtual machines" die all at the
> same time from a single kernel panic.

Yes, absolutely it would.  I use the OpenVZ kernels that are based on the RHEL4 and RHEL5 kernels and I haven't had any problems with them... just like I haven't had any problems with the stock RHEL4 and RHEL5 kernels... nor CentOS kernels.

I usually end up rebooting host node machines because of kernel upgrades... so my machines don't get a chance to have longish uptimes... but on one remote colocation machine I have for hobby stuff... it currently has an uptime of 106 days.  It has 7 VPSes on it and they are fairly fat as they all run a full set of services.  I know I've been running that machine for close to 2 years now... and if I remember correctly it started out with CentOS 4.0.  I've upgraded to each release (on the host node and the VPSes) and am currently at CentOS 4.5.  I look foward forward to 4.6.

Here's what they look like (ip addresses and hostnames obscured):

[root at hn ~]# vzlist
      VEID      NPROC   STATUS     IP_ADDR         HOSTNAME
       101         53        running    xx.xx.xx.xx    vps101.localdomain
       102         44        running    xx.xx.xx.xx    vps102.localdomain
       103         44        running    xx.xx.xx.xx    vps103.localdomain
       104         32        running    xx.xx.xx.xx    vps104.localdomain
       105        322       running    xx.xx.xx.xx    vps105.localdomain
       106         32        running    xx.xx.xx.xx    vps106.localdomain
       107         29        running    xx.xx.xx.xx    vps107.localdomain

Looking at the number of processes, can you tell which VPS is running Zimbra? :)

6 of the 7 VPSes are CentOS and the remaining 1 is Debian.

Speaking of uptimes, I have a "legacy" machine at work running Linux-VServer on a 2.4.x series kernel.  It had the longest uptime of any machine I've had... and was well over 400 days... when a power outage that outlasted its UPS took it down.  That particular machine runs three VPSes that are mail relay/frontends and they get pounded... so that uptime is notable.

So, my experience has been that physical failures and power failures (although pretty rare) are more common that kernel panics that take down all of my virtual machines.

Scott Dowdle
704 Church Street
Belgrade, MT 59714
(406)388-0827 [home]
(406)994-3931 [work]