[Bug 1431406] Re: Stale iSCSI sessions when detaching a volume from Windows VM while online
James Page
james.page at ubuntu.com
Thu Sep 8 11:48:38 UTC 2016
** Changed in: cinder (Ubuntu)
Importance: Undecided => Medium
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https://bugs.launchpad.net/bugs/1431406
Title:
Stale iSCSI sessions when detaching a volume from Windows VM while
online
Status in Cinder:
New
Status in cinder package in Ubuntu:
New
Bug description:
We are regularly encountering this situation when deleting stacks
managed by Heat. It can be reproduced without heat, however, just
using Nova and Cinder:
1. Create a Windows guest VM, for example using CloudBase's image
windows_server_2012_r2_standard_eval_kvm_20140607.
2. Create a Volume (50 GB) and attach volume to the instance.
3. Log into instance. Start Computer Mangement -> Disk Management.
4. Online the disk. Initialize and format the volume, assign drive
letter D. Create some small garbage data on D:.
5. In Nova detach volume from instance. (Without shutting down the
instance first. This is apparently what Heat does when deleting a
stack.)
On the compute node you will now see dmesg and syslog being flooded
with messages like
[768938.979494] connection18:0: detected conn error (1020)
about once per second. On the compute node
iscsiadm --mode session --print=1
displays the iSCSI initiatior session still logged in, while on the
Cinder storage node
tgtadm --lld iscsi --op show --mode target
shows that the iSCSI target is gone. The recurring connection errors
on the compute node persist until manually logging off the iSCSI
session. You may argue that performing the detachment while the volume
is online and in use is unclean, therefore the issue being Heat's
responsibility. However, even if that was the case, such an operation
should not result in stale iSCSI sessions accumulating until manual
intervention via root shell on the compute node.
Additional information:
- We couldn't reproduce this problem with Linux quest instances. Even
when detaching a volume while mounted and in use by the instance,
iSCSI session are cleaned up gracefully.
- We can reproduce this problem with both Icehouse and Juno.
- We can reproduce the problem with both single and multi node
OpenStack configurations, the latter using separate hosts for compute
and storage.
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