Created attachment 1427604 [details]
Description of problem:
The error msg is not clear when blkdeviotune a cdrom without media for a running guest
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1.add a cdrom without media to guest xml:
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='hda' bus='ide'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
2.#virsh start 02test
3.# virsh blkdeviotune 02test hda
error: Unable to get block I/O throttle parameters
error: internal error: block_io_throttle inserted entry was not in expected format
1. In step3,executed # virsh blkdeviotune 02test hda ,report unclear error.
2. The error behaves differently with a shutoff scenario, refer to addtional info.
The error should show its specific reason(empty disk or sth), to distinguish with other potential issues such as bz872582.
1. when guest shutoff, it gives an output:
# virsh shutdown 02test
# virsh blkdeviotune 02test hda
read_bytes_sec : 0
total_iops_sec : 0
read_iops_sec : 0
write_iops_sec : 0
size_iops_sec : 0
2. when guest running with a media in cdrom, it works well.
The IO tuning stuff will be completely refactored when doing blockdev implementation, so that may actually fix it.
(In reply to Peter Krempa from comment #2)
Any possibility that it would fix Bug 1377648, Bug 1344897 and Bug 1344897 as well? Feel free to take all those BZ if you think it might. You'll also know how it might be tied together in the code after the refactor.
This bug was closed deferred as a result of bug triage.
Please reopen if you disagree and provide justification why this bug should
get enough priority. Most important would be information about impact on
customer or layered product. Please indicate requested target release.