Red Hat Bugzilla – Bug 430542
If write back cache used scsi layer is not sending sync cache to disk
Last modified: 2012-06-27 05:27:15 EDT
Description of problem:
SCSI layer should be sending sync cache to disk when removing or shutting down
disk if write cache is enabled.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. echo 1 > /sys/block/sdX/device/delete
Do not see a sync cache command being sent by the scsi layer.
Should see a "Synchronizing SCSI cache" message in the log, and a sync cache
command in a trace.
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release. Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products. This request is not yet committed for inclusion in an Update
(In reply to comment #0)
> Steps to Reproduce:
> 1. echo 1 > /sys/block/sdX/device/delete
Bad test example. This does not seem to work on 5.1 either.
If you reboot or shutdown the system though, the sync cache would get sent in
5.1 and RHEL4, but does not in 5.2.
It looks like there is a reordering of some driver model or scsi device teardown
This bugzilla has Keywords: Regression.
Since no regressions are allowed between releases,
it is also being proposed as a blocker for this release.
Please resolve ASAP.
For 5.2, we just do not print out the cache sync message during reboot/shutdown.
It still gets sent and executed.
For all RHEL5 kernels, we do not send the cache sync when manually removing a
device like with "echo 1 > /sys/block/sdX/device/delete".
So there is no regression.
We should send the cache sync during manual removal, but it is too late to fix
this, so I am putting this bug up for 5.3.
This did not make 5.3, due to a lack of resources. Proposing for 5.4.
Updating PM score.