Red Hat Bugzilla – Bug 1316287
Possible QEMU deadlock after creating image snapshots
Last modified: 2017-07-30 11:35:50 EDT
Description of problem:
Creating a snapshot out-of-band (e.g. rbd snap create image@snap) on an image with active IO might result in all IO hanging within the QEMU process. This only occurs when the RBD cache is enabled.
Version-Release number of selected component (if applicable):
Requires that the RBD cache have pending writeback IO when a snapshot is created.
Steps to Reproduce:
1. Start a write-intensive operation within a VM
2. Create a snapshot of the RBD image
QEMU IO will hang
QEMU IO continues without issue
This issue only affects 1.3.x -- it doesn't affect 2.0. Resetting the flags to account for the change.
Fixed in v0.94.7 upstream. We'll take this BZ as part of the rebase (bz 1335269).
Verified in ceph version:
ceph version 0.94.9-1.el7cp
1. enable rbd caching.
2. attach a RBD image to a KVM instance.
3. start IO on the RBD image from the VM.
4. Take snapshots of the RBD image.
5. clone a snapshot.
No imapct to IO.
Moving this to Verified.
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.