[Xen-devel] Unable to start more than 103 VMs

["Carb, Brian A" <Brian.Carb@xxxxxxxxxx>]

Unable to start more than 103 VMs. Any ideas?

 

Running Xen Unstable (changeset 15445) on a Unisys ES7000/one on SLES10 Release, 64gb memory, 16 cpu, dom0_mem=512M, xenheap_megabytes=64. VMs are SLES10 para-virtual guests, each on their own lun on san storage.

 

We can start 103 VMs successfully. When starting the 104th, the VM times out waiting for its disk to appear:

XENBUS: Timeout connecting to device: device/vbd/2048 (state 6)
XENBUS: Timeout connecting to device: device/vif/0 (state 6)
XENBUS: Device with no driver: device/console/0
BIOS EDD facility v0.16 2004-Jun-25, 0 devices found
EDD information not available.
Freeing unused kernel memory: 172k freed
Starting udevd
Creating devices
Loading jbd
jbd: no version for "struct_module" found: kernel tainted.
Loading ext3
Loading reiserfs
Loading jbd
Loading ext3
Waiting for device /dev/sda2 to appear: ..............................not found -- exiting to /bin/sh
sh: no job control in this shell
$

 

Noteworthy:

  - domain-0 can see the lun of the failing VM correctly, and there are no errors if we run kpartx and mount the VMs root partition.

  - we can reproduce the problem on xen-3.1 as well as xen-unstable.

  - problem still occurs if we split the VMs across 2 bridges - the 104th still fails.

  - problem also occurs if we start the VMs in any order - once 103 are started, the next one fails.

  - if we comment out the "vif = " statement in the VM config files, we can start more than 103

brian carb
unisys corporation - malvern, pa

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