RE: [Xen-users] Only able to start 2 domUs

["John Anderson" <johna@xxxxxxxxxx>]

I had similar problems when using file backed VBDs.  The problem was I
was fresh out of loopback devices.  The solution was to pass
max_loop=<n> to the dom0 kernel at boot time.  Or you can pass
max_loop=<n> to the loop kernel module when it is loaded.  

If you are using an initrd with each domU, then you may be running out
of ram devices.  If you only have two /dev/loop* or two /dev/ram*
devices, then you may need to edit your kernel config to specify more
devices, or pass the options at boot time.


-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Eric E
Sent: Friday, June 16, 2006 1:52 PM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Only able to start 2 domUs

Hi,
    I've been running Xen 2.0.7 successfully on Suse 9.3 for some time.

Recently I installed Xen 3.0 on SLES9, and have been able to get domains

running just fine.  I've recently run into a problem: I can only launch 
2 domains at once.  When I attempt to launch the third domain, I get:
Error: Device 2049 (vbd) could not be connected. Backend device not
found.
Taking one down allows me to start a different domain, so each works 
when only one other is up.

I'm running this on a Dell PowerEdge 2850 with 6GB of RAM and two NICs, 
respectively called eth0 and eth1.  I've assigned random, made-up MAC 
addresses to each, and no files or partitions are being re-used.  We had

to assign eth1 to a bridge xenbr1 in order to get xenbr0 to work, but we

do not use eth1 or xenbr1 at the moment.  Xend-log output follows

Does anyone have any idea why a third domain won't boot?

Thanks,

Eric



[2006-06-16 20:43:48 xend] INFO (image:135) buildDomain os=linux dom=24 
vcpus=1
[2006-06-16 20:43:48 xend] DEBUG (image:173) dom            = 24
[2006-06-16 20:43:48 xend] DEBUG (image:174) image          = 
/boot/vmlinuz-2.6-xen
[2006-06-16 20:43:48 xend] DEBUG (image:175) store_evtchn   = 1
[2006-06-16 20:43:48 xend] DEBUG (image:176) console_evtchn = 2
[2006-06-16 20:43:48 xend] DEBUG (image:177) cmdline        =  
root=/dev/sda1 rw 3
[2006-06-16 20:43:48 xend] DEBUG (image:178) ramdisk        = 
/boot/initrd-xen
[2006-06-16 20:43:48 xend] DEBUG (image:179) vcpus          = 1
[2006-06-16 20:43:48 xend] DEBUG (image:180) features       =
[2006-06-16 20:43:48 xend] DEBUG (DevController:103) DevController: 
writing {'virtual-device': '2049', 'backend-id': '0', 'state': '1', 
'backend': '/local/domain/0/backend/vbd/24/2049'} to 
/local/domain/24/device/vbd/2049.
[2006-06-16 20:43:48 xend] DEBUG (DevController:105) DevController: 
writing {'domain': 'limsdev', 'frontend': 
'/local/domain/24/device/vbd/2049', 'dev': 'sda1', 'state': '1', 
'params': '/mnt/images/limsdev_pgsql_xen.img', 'mode': 'w', 
'frontend-id': '24', 'type': 'file'} to
/local/domain/0/backend/vbd/24/2049.
[2006-06-16 20:43:48 xend] DEBUG (DevController:103) DevController: 
writing {'virtual-device': '2050', 'backend-id': '0', 'state': '1', 
'backend': '/local/domain/0/backend/vbd/24/2050'} to 
/local/domain/24/device/vbd/2050.
[2006-06-16 20:43:48 xend] DEBUG (DevController:105) DevController: 
writing {'domain': 'limsdev', 'frontend': 
'/local/domain/24/device/vbd/2050', 'dev': 'sda2', 'state': '1', 
'params': '/dev/system_lvm/limsdev_data', 'mode': 'w', 'frontend-id': 
'24', 'type': 'phy'} to /local/domain/0/backend/vbd/24/2050.
[2006-06-16 20:43:48 xend] DEBUG (DevController:103) DevController: 
writing {'backend-id': '0', 'mac': '00:16:3e:aa:06:21', 'handle': '0', 
'state': '1', 'backend': '/local/domain/0/backend/vif/24/0'} to 
/local/domain/24/device/vif/0.
[2006-06-16 20:43:48 xend] DEBUG (DevController:105) DevController: 
writing {'bridge': 'xenbr0', 'domain': 'limsdev', 'handle': '0', 
'script': '/etc/xen/scripts/vif-bridge', 'state': '1', 'frontend': 
'/local/domain/24/device/vif/0', 'mac': '00:16:3e:aa:06:21', 
'frontend-id': '24'} to /local/domain/0/backend/vif/24/0.
[2006-06-16 20:43:48 xend.XendDomainInfo] DEBUG (XendDomainInfo:671) 
Storing VM details: {'ssidref': '0', 'uuid': 
'e832ec8c-9eb7-d851-234b-4cd81c279d06', 'on_reboot': 'restart', 
'start_time': '1150505028.48', 'on_poweroff': 'destroy', 'name': 
'limsdev', 'vcpus': '1', 'vcpu_avail': '1', 'memory': '400', 'on_crash':

'restart', 'image': "(linux (kernel /boot/vmlinuz-2.6-xen) (ramdisk 
/boot/initrd-xen) (root '/dev/sda1 rw') (args 3))", 'maxmem': '400'}
[2006-06-16 20:43:48 xend.XendDomainInfo] DEBUG (XendDomainInfo:696) 
Storing domain details: {'console/ring-ref': '209107', 'console/port': 
'2', 'name': 'limsdev', 'console/limit': '1048576', 'vm': 
'/vm/e832ec8c-9eb7-d851-234b-4cd81c279d06', 'domid': '24', 
'cpu/0/availability': 'online', 'memory/target': '409600', 
'store/ring-ref': '209108', 'store/port': '1'}
[2006-06-16 20:43:48 xend.XendDomainInfo] DEBUG (XendDomainInfo:877) 
XendDomainInfo.handleShutdownWatch
[2006-06-16 20:43:48 xend] DEBUG (DevController:132) Waiting for devices

vif.
[2006-06-16 20:43:48 xend] DEBUG (DevController:138) Waiting for 0.
[2006-06-16 20:43:48 xend] DEBUG (DevController:403) 
hotplugStatusCallback /local/domain/0/backend/vif/24/0/hotplug-status.
[2006-06-16 20:43:54 xend] DEBUG (DevController:403) 
hotplugStatusCallback /local/domain/0/backend/vif/24/0/hotplug-status.
[2006-06-16 20:43:54 xend] DEBUG (DevController:417) 
hotplugStatusCallback 1.
[2006-06-16 20:43:54 xend] DEBUG (DevController:132) Waiting for devices

usb.
[2006-06-16 20:43:54 xend] DEBUG (DevController:132) Waiting for devices

vbd.
[2006-06-16 20:43:54 xend] DEBUG (DevController:138) Waiting for 2049.
[2006-06-16 20:43:54 xend] DEBUG (DevController:403) 
hotplugStatusCallback
/local/domain/0/backend/vbd/24/2049/hotplug-status.
[2006-06-16 20:43:54 xend] DEBUG (DevController:417) 
hotplugStatusCallback 2.
[2006-06-16 20:43:54 xend.XendDomainInfo] DEBUG (XendDomainInfo:1327) 
XendDomainInfo.destroy: domid=24
[2006-06-16 20:43:54 xend.XendDomainInfo] DEBUG (XendDomainInfo:1335) 
XendDomainInfo.destroyDomain(24)

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