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Bug 729714 - libvirt managedsave incompatible with transient domains
Summary: libvirt managedsave incompatible with transient domains
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: libvirt
Version: 6.2
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Eric Blake
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-08-10 15:35 UTC by Eric Blake
Modified: 2011-12-06 11:26 UTC (History)
6 users (show)

Fixed In Version: libvirt-0.9.4-3.el6
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2011-12-06 11:26:05 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2011:1513 0 normal SHIPPED_LIVE libvirt bug fix and enhancement update 2011-12-06 01:23:30 UTC

Description Eric Blake 2011-08-10 15:35:01 UTC 
Description of problem:
The fix to bug 697742 made it impossible to undefine a domain if managed save state still exists, since otherwise, the existing managedsave data can interfere with a new domain created by the same name.  However, this overlooked one aspect - transient domains cannot be undefined, but cease to exist once the qemu process stops; yet the managedsave process causes the qemu process to stop.  Thus, attempts to use managedsave on a transient domain will create stale state files that can interfere with the creation of new domains.

Version-Release number of selected component (if applicable):
libvirt-0.9.4-2.el6

How reproducible:
found by code inspection, but I suspect it is possible to write a test case with 100% reproduction

Steps to Reproduce (untested, based on steps in bug 697742):
1. create a transient domain "dom"
2. virsh managedsave dom
3. note that 'virsh start dom' won't work, since dom no longer exists
4. define a new persistent domain named dom but with a different uuid
5. virsh start dom
  
Actual results:
since step 2 succeeded, step 5 ends up trying to revive the managedsave associated with the old transient 'dom', instead of booting the new persistent 'dom' from scratch, and fails due to uuid collision.

Expected results:
step 2 should be rejected - managedsave of a transient domain does not make sense

Additional info:
Patch proposed upstream, awaiting feedback on whether rejection is right, or whether the patch should be rewritten to permit managedsave on transient domains by temporarily making the domain persistent.
https://www.redhat.com/archives/libvir-list/2011-August/msg00339.html
Comment 1 Daniel Veillard 2011-08-11 03:06:44 UTC 
I ACK'ed the patch upstream as I think that by definition transient domains
are to be managed by the application on top of libvirt. That's a design choice
and I think the API is consistent with this, in that case really it's a missing
check from my POV,

Daniel
Comment 2 Daniel Veillard 2011-08-15 02:43:10 UTC 
Commited upstream as 0de75e855b0c37a7ef25370b19cabad34e679ce6
Comment 4 dyuan 2011-08-16 08:02:10 UTC 
Reproduce this issue with libvirt-0.9.4-2.el6.

# virsh create dom.xml 
Domain dom-create created from dom.xml

# virsh list --all
 Id Name                 State
----------------------------------
  8 dom-create           running

# virsh managedsave dom-create
Domain dom-create state saved by libvirt

# virsh list --all
 Id Name                 State
----------------------------------

# virsh define dom.xml 
Domain dom-create defined from dom.xml

# virsh start dom-create
error: Failed to start domain dom-create
error: operation failed: cannot restore domain 'dom-create' uuid a89394e5-d6d5-e87b-a270-8246ecbb3a98 from a file which belongs to domain 'dom-create' uuid 4d662f3b-99ff-4b31-60cb-7b7fa1f922be


Verified PASS with libvirt-0.9.4-4.el6.

# virsh create dom.xml 
Domain dom-create created from dom.xml

# virsh list --all
 Id Name                 State
----------------------------------
  8 dom-create           running

# virsh managedsave dom-create
error: Failed to save domain dom-create state
error: Requested operation is not valid: cannot do managed save for transient domain

# virsh list --all
 Id Name                 State
----------------------------------
  8 dom-create           running
Comment 5 errata-xmlrpc 2011-12-06 11:26:05 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2011-1513.html
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