Martin Tröster
2009-Jan-20 15:22 UTC
[Xen-users] Xen 3.3.0 - QEMU COW disk image with sparse backing file - VM fails to start
Hi, I upgraded my Xen 3.2-based test system to Xen 3.3. With this installation, I am no longer able to start images with COW disk images based on qcow sparse files. Starting the DomU via xm create gives success status (with "Startig Domain test" message printed to console), but xm list directly afterwards shows no entry for the VM. The image structure is: Base File A.img (sparse QCOW2 file) COW File B.img (QCOW2 file with A.img as backing file) used as disk in Xen config file (see VM config file below) I am running a CentOS 5.2 server with the pre-build packages at http://www.gitco.de/repro and can repro this behaviour on both 3.3.0 and 3.3.1RC1_pre (no 3.3.1 final version available, no time yet to do a build on my own). In detail, I see the following behaviour: -> RAW image with disk using file:/ - works -> QCOW sparse image using tap:qcow - works -> QCOW image based on RAW image using tap:qcow - works -> QCOW image based on QCOW sparse image using tap:qcow - fails. Logs of failing case: ============================/var/log/xen/xend.log shows that the domain immediately terminates, but no ERROR indication: [2009-01-20 09:13:55 20596] DEBUG (XendDomainInfo:1443) XendDomainInfo.handleShutdownWatch [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices vif. [2009-01-20 09:13:55 20596] DEBUG (DevController:160) Waiting for 0. [2009-01-20 09:13:55 20596] DEBUG (DevController:645) hotplugStatusCallback /local/domain/0/backend/vif/8/0/hotplug-status. [2009-01-20 09:13:55 20596] DEBUG (DevController:645) hotplugStatusCallback /local/domain/0/backend/vif/8/0/hotplug-status. [2009-01-20 09:13:55 20596] DEBUG (DevController:659) hotplugStatusCallback 1. [2009-01-20 09:13:55 20596] DEBUG (DevController:160) Waiting for 1. [2009-01-20 09:13:55 20596] DEBUG (DevController:645) hotplugStatusCallback /local/domain/0/backend/vif/8/1/hotplug-status. [2009-01-20 09:13:55 20596] DEBUG (DevController:659) hotplugStatusCallback 1. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices vscsi. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices vbd. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices irq. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices vkbd. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices vfb. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices console. [2009-01-20 09:13:55 20596] DEBUG (DevController:160) Waiting for 0. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices pci. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices ioports. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices tap. [2009-01-20 09:13:55 20596] DEBUG (DevController:160) Waiting for 51712. [2009-01-20 09:13:55 20596] DEBUG (DevController:645) hotplugStatusCallback /local/domain/0/backend/tap/8/51712/hotplug-status. [2009-01-20 09:13:55 20596] DEBUG (DevController:659) hotplugStatusCallback 1. [2009-01-20 09:13:55 20596] DEBUG (DevController:155) Waiting for devices vtpm. [2009-01-20 09:13:55 20596] INFO (XendDomain:1172) Domain test (8) unpaused. [2009-01-20 09:13:57 20596] INFO (XendDomainInfo:1634) Domain has shutdown: name=test id=8 reason=poweroff. [2009-01-20 09:13:57 20596] DEBUG (XendDomainInfo:2389) XendDomainInfo.destroy: domid=8 [2009-01-20 09:13:57 20596] DEBUG (XendDomainInfo:2406) XendDomainInfo.destroyDomain(8) [2009-01-20 09:13:57 20596] DEBUG (XendDomainInfo:1939) Destroying device model [2009-01-20 09:13:57 20596] DEBUG (XendDomainInfo:1946) Releasing devices [2009-01-20 09:13:57 20596] WARNING (image:472) domain test: device model failure: no longer running; see /var/log/xen/qemu-dm-test.log /var/log/xen/qemu-dm-test.log shows nothing spectacular at all (at least for me): domid: 8 qemu: the number of cpus is 1 config qemu network with xen bridge for tap8.0 xenbr0 config qemu network with xen bridge for tap8.1 eth0 Using xvda for guest''s hda Strip off blktap sub-type prefix to /path/to/test.img (drv ''qcow'') Watching /local/domain/0/device-model/8/logdirty/next-active Watching /local/domain/0/device-model/8/command qemu_map_cache_init nr_buckets = 10000 size 3145728 shared page at pfn 3fffe buffered io page at pfn 3fffc Time offset set 0 Register xen platform. Done register platform. /var/log/messages also shows nothing remarkable. Interesting entries never seen before are: Jan 19 17:50:02 test kernel: tapdisk[21929] general protection rip:40b315 rsp:42900108 error:0 but they occur all the time on Xen 3.3 and Xen 3.3.1 using qcow images (but seem to be recovered) VM config file: ------------------------------------------------------------------------------------------ name = "test" device_model = ''/usr/lib64/xen/bin/qemu-dm'' builder = "hvm" kernel = "/usr/lib/xen/boot/hvmloader" # hardware memory = "1024" disk = [ ''tap:qcow:/path/to/B.img,ioemu:xvda,w'' ] vcpus=1 # network vif = [ ''type=ioemu,mac=02:00:00:00:00:01'',''type=ioemu,bridge=eth0,mac=02:00:00:00:01:98'' ] dhcp = "dhcp" # visualization sdl = 0 vnc = 1 vncviewer = 0 ------------------------------------------------------------------------------------------ Any help is appreciated. Thanks! Cheers, Martin ____________________________________________________________________ Psssst! 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