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[Xen-devel] XEN 4.0 + pvops kernel : system crashes on startin

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Subject: [Xen-devel] XEN 4.0 + pvops kernel : system crashes on starting 155th domU
From: "Yuvraj Agarwal" <yuvraj@xxxxxxxxxxx>
Date: Tue, 27 Apr 2010 00:41:07 -0700 (PDT)
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Hi All,


We are setting up a system with a large number of very small VMs for a project. We worked through a number of limitations, including those imposed by blktap2 devices and the number of dynamic IRQ (set kernel config NR_CPUS) etc. After these changes we were able to get to  154 domUs (!), but as soon as we start up the 155th domU the system crashes. We edited each domU config to have one blktap2 device (the disk image) and two virtual network interfaces each.


We are using the standard XEN 4.0 (stable/release version)  with the (pvops) kernel.


Attached is the output of /var/log/daemon.log and /var/log/xen/xend.log, but as far as we can see we don’t quite know what might be going causing the system to crash (no console access anymore and system becomes unresponsive and needs to be power-cycled).  I have pasted only the relevant bits of information (the last domU that did successfully start and the next one that failed). It may be the case that all the log messages weren’t flushed before the system crashed…


Does anyone know where this limit of 155 domU is coming from and how we can fix/increase it?



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