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

[Eric E <whalesuit@xxxxxxxxx>]

Thanks to both John and Serge for the advice, but that doesn't seem to 
be the problem.  I set max_loop to 64,
and  ls -l /dev/loop* gives:
   brw-rw----  1 root disk 7,  0 May 24  2005 /dev/loop0
   brw-rw----  1 root disk 7,  1 May 24  2005 /dev/loop1
   brw-rw----  1 root disk 7, 10 May 24  2005 /dev/loop10
   brw-rw----  1 root disk 7, 11 May 24  2005 /dev/loop11
   brw-rw----  1 root disk 7, 12 May 24  2005 /dev/loop12
   brw-rw----  1 root disk 7, 13 May 24  2005 /dev/loop13
   brw-rw----  1 root disk 7, 14 May 24  2005 /dev/loop14
   brw-rw----  1 root disk 7, 15 May 24  2005 /dev/loop15
   brw-rw----  1 root disk 7,  2 May 24  2005 /dev/loop2
   brw-rw----  1 root disk 7,  3 May 24  2005 /dev/loop3
   brw-rw----  1 root disk 7,  4 May 24  2005 /dev/loop4
   brw-rw----  1 root disk 7,  5 May 24  2005 /dev/loop5
   brw-rw----  1 root disk 7,  6 May 24  2005 /dev/loop6
   brw-rw----  1 root disk 7,  7 May 24  2005 /dev/loop7
   brw-rw----  1 root disk 7,  8 May 24  2005 /dev/loop8
   brw-rw----  1 root disk 7,  9 May 24  2005 /dev/loop9

and likewise  ls -l /dev/ram*  gives:
   lrwxrwxrwx  1 root root    4 Jun 12 04:03 /dev/ram -> ram0
   brw-rw----  1 root disk 1, 0 May 24  2005 /dev/ram0
   brw-rw----  1 root disk 1, 1 May 24  2005 /dev/ram1
   brw-rw----  1 root disk 1, 2 May 24  2005 /dev/ram2
   brw-rw----  1 root disk 1, 3 May 24  2005 /dev/ram3
   brw-rw----  1 root disk 1, 4 May 24  2005 /dev/ram4
   brw-rw----  1 root disk 1, 5 May 24  2005 /dev/ram5
   brw-rw----  1 root disk 1, 6 May 24  2005 /dev/ram6
   brw-rw----  1 root disk 1, 7 May 24  2005 /dev/ram7
   lrwxrwxrwx  1 root root    4 Jun 12 04:03 /dev/ramdisk -> ram0

when I'm running two domains,  losetup -a gives me:
/dev/loop0: [0805]:5 (/mnt/images/dom1.img)
/dev/loop1: [0805]:6 (/mnt/images/dom2.img)

I've also been able to mount about 10 iso images directly within dom0 
with no problems.
Any other ideas?

Thanks,

Eric

John Anderson wrote:
> 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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