[vbox-dev] Linux Host VM Cap?

[Knut St. Osmundsen]

Hi Zak!

The VMM imposes a limit of 1023 VMs on 64-bit hosts and 127 VMs on 32-bit hosts.  See:
	http://www.virtualbox.org/browser/trunk/src/VBox/VMM/VMMR0/GVMMR0.cpp#L121

Seeing you have 2TB of memory and 128 cores, I would assume you're running 64-bit Ubuntu. So, it is probably some other limit that you're hitting. It could be SysV semaphores, it could be memory available below 4GB, ... Could you please provide some more details regarding what happens when you are unable to launch more VMs? For instance, does a new VBox.log file get created for the VM? If it does, please zip it up and send it to me (or Klaus) per private mail and we'll work it out.


On Apr 29, 2011, at 7:43 PM, Zak Perschon wrote:

> Ah, sorry forgot to include the original support thread. The limit I hit was 128 active VMs at once. Once I hit that number, I was unable to launch any more unless I stopped one that was already running. My original thread can be found here (though there is little information contained in it): http://forums.virtualbox.org/viewtopic.php?f=7&t=40955
> 
> -Zak
> 
> > Date: Fri, 29 Apr 2011 16:25:44 +0200
> > From: klaus.espenlaub at oracle.com
> > To: vbox-dev at virtualbox.org
> > Subject: Re: [vbox-dev] Linux Host VM Cap?
> > 
> > On 25.04.2011 18:00, Zak Perschon wrote:
> > >
> > > I've come across what is seemingly a hard cap for the amount of
> > > concurrent VMs I can run on a Linux based machine (after posting on the
> > > support forums, I was directed here). Apparently this same cap was
> > > encountered on a solaris host and a fix was deployed to increase the
> > > amount of VMs that were allowed to run at the same time. Was this fix
> > > supposed to be included in other OS releases? Any information on this
> > > would be greatly appreciated.
> > 
> > That's a rather vague statement, and if you could tell what number of 
> > concurrently running VMs you can achieve I might be able to infer what 
> > limit is causing trouble for you.
> > 
> > It could be the SysV semaphore count, the number of open files per 
> > process, and so on. All these defaults depend on the kernel 
> > configuration and/or distribution, so it's hard to generalize.
> > 
> > Solaris is easy compared to that, as it is very uniform compared to Linux.
> > 
> > Klaus
> > 
> > >
> > > Here is the information on the hardware/VM profiles I am using
> > >
> > > Host Machine:
> > > 128 Processor Cores (64 dual core Xenon processors running at 2.27 GHz)
> > > 2.0 TB Memory (1.8~ Usable)
> > > 1.8 TB RAID 0 (6 x 300GB HDD running at 10k RPM)
> > > 16TB SAS
> > >
> > > VM Profile
> > > Compiled TinyCore Linux 2.6
> > > Required Memory: 150~MB
> > > Required HDD Space: 50MB
> > >
> > > -Zak
> > 
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Kind regards / Mit freundlichen Gruessen / Vennlig hilsen,
 bird

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ORACLE Deutschland B.V. & Co. KG  Knut St. Osmundsen
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