Disk attach and detach

[zhanglidonga]

problem

This situation often occurs during disk operations

versions

4.19

The steps to reproduce the bug

1. Create VM
2. Add a disk
3. Mount the disk
4. Disassemble the disk
5. Repeated operations such as taking a snapshot, restoring the snapshot, and deleting the snapshot will result in issues

What to do about it?

Upon checking the logs, it was found that the instruction may have been sent to the agent but could not be sent. However, upon examining the code, the specific reason cannot be determined as it will recover shortly and may occur at any time thereafter, with the possibility of self repair.

[DaanHoogland]

@zhanglidonga ,
Did you try to detach a disk while a snapshot of the vm with that disk attached is present? This is known to can cause problems.
Also, do I understand correctly that the issue is intermittently present and not present?

[DaanHoogland]

@zhanglidonga can you also add information on what type of hypervisor/storage and what versions?

[zhanglidonga]

@zhanglidonga , Did you try to detach a disk while a snapshot of the vm with that disk attached is present? This is known to can cause problems. Also, do I understand correctly that the issue is intermittently present and not present?

Yes, sometimes good and sometimes bad. Regarding the issue of snapshots, the current version of snapshots used is disk based and does not have virtual machine snapshots.

[zhanglidonga]

can you also add information on what type of hypervisor/storage and what versions?

Is this the type?

[DaanHoogland]

can you also add information on what type of hypervisor/storage and what versions?

@zhanglidonga I meant, are you using KVM/Xen/Vmware and what version of those.

[zhanglidonga]

can you also add information on what type of hypervisor/storage and what versions?

@zhanglidonga I meant, are you using KVM/Xen/Vmware and what version of those.

I used KVM for virtualization and did not use any other methods

[DaanHoogland]

@zhanglidonga two things to check

1. are qemu and libvirt compatible?
2. is the disk being used in the OS of the client?

[zhanglidonga]

• are qemu and libvirt compatible?
• is the disk being used in the OS of the client?

1. Very compatible, no other issues . Or you can tell me which specific versions to use.
2. After connecting to the virtual machine, the disk was formatted first, and then the files were copied. As for whether you were referring to uninstalling during the copying process? I don't usually intentionally create this situation, so I can test it for this scenario.

[DaanHoogland]

ok, the versions look good to me. I am not the expert on which versions will work or not.
As for testing, your scenarios seem valid and should fail imho. Especially detaching a busy device. so umount in the OS first and then detach should succeed, otherwise not.