Created attachment 1423686 [details]
Description of problem:
Basic backup restore API scenario of VM start while it has a snapshot disk attached, resides on an iSCSI domain, fails with libvirtError.
Version-Release number of selected component (if applicable):
Red Hat Enterprise Linux Server 7.5 (Maipo)
Can't re-test this as the PPC env we have in RHV QE is not available for the time being. Will re-execute the test case once the env is back.
Steps to Reproduce:
1. Create VM (source VM) with disk attached on iscsi domain
2. Create a snapshot for the source VM
3. Create a second VM (backup VM)
4. Attach the backup disk snapshot of source VM to the backup VM (via REST)
5. Start backup VM
Start VM fails:
2018-04-17 19:11:03,926+0300 ERROR (vm/9165385b) [virt.vm] (vmId='9165385b-f28b-4474-990b-4391f0be2b47') The vm start process failed (vm:943)
Traceback (most recent call last):
File "/usr/lib/python2.7/site-packages/vdsm/virt/vm.py", line 872, in _startUnderlyingVm
File "/usr/lib/python2.7/site-packages/vdsm/virt/vm.py", line 2872, in _run
File "/usr/lib/python2.7/site-packages/vdsm/common/libvirtconnection.py", line 130, in wrapper
ret = f(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/vdsm/common/function.py", line 92, in wrapper
return func(inst, *args, **kwargs)
File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1099, in createWithFlags
if ret == -1: raise libvirtError ('virDomainCreateWithFlags() failed', dom=self)
libvirtError: unsupported configuration: native I/O needs either no disk cache or directsync cache mode, QEMU will fallback to aio=threads
2018-04-17 19:11:03,926+0300 INFO (vm/9165385b) [virt.vm] (vmId='9165385b-f28b-4474-990b-4391f0be2b47') Changed state to Down: unsupported configuration: native I/O needs either no disk cache or directsync cache mode, QEMU will fallback to aio=threads (code=1) (vm:1683)
VM should start
2018-04-17 19:11:06,116+03 ERROR [org.ovirt.engine.core.dal.dbbroker.auditloghandling.AuditLogDirector] (ForkJoinPool-1-worker-15)  EVENT_ID: VM_DOWN_ERROR(119), VM backup_vm_TestCase6183_1719104052 is down with error. Exit message: unsupported configuration: native I/O needs either no disk cache or directsync cache mode, QEMU will fallback to aio=threads.
Marked regression as this test has passed with rhv-4.2.2-10 on RHV automation tier1 from April 8.
likely fixed by https://gerrit.ovirt.org/#/c/90287/, please retest with 4.2.3-2
Not specific to PPC, reproduced also on x86_64.
Michal, indeed, in 4.2.3-2 the bug does not occur.
Please add the gerrit external tracker and can move to ON_QA, I'll verify.
Start VM, with snapshot disk attached, succeeds on all storage types - tested with iscsi, fcp, nfs and gluster.
This bugzilla is included in oVirt 4.2.3 release, published on May 4th 2018.
Since the problem described in this bug report should be
resolved in oVirt 4.2.3 release, it has been closed with a resolution of CURRENT RELEASE.
If the solution does not work for you, please open a new bug report.