[ovirt-users] oVirt 4.2 - Removed disk remains in VM OS with hooks?

[Yaniv Kaul]

On Jan 22, 2018 5:32 PM, "Zip" <plord at intricatenetworks.com> wrote:


I am having an issue where when I use the REST API to connect a snapshot
> from another VM to a Backup-Appliance-VM, after the clone when I remove the
> Disk and delete the Snapshot, the disk remains in the Backup-Appliance-VM
> as /dev/sdb ot /dev/vdb.
>
> If I reboot the Bakup-Applicance-VM the disk disappears.
>
> If I manually remove the disk by "echo 1 > /sys/block/sdb/device/delete”
> the disk will disappear, but if I rescan the scsi bus, it is found and
> shows up again in the VM OS, but the oVirt WebGUI does NOT show it as
> connected.
>

-- The first part is expected - the 2nd isn't.

What are you referring to as the first and second part?


I understand why the disk is seen after it was detached (stale device), not
why it comes back after rescan, which seems to suggest it is not detached
properly.




>
> I am also not able to attach any other disks as it complains of :
>
> HotPlugDiskVDS failed: internal error: unable to execute QEMU command
> '__com.redhat_drive_add': Duplicate ID 'drive-scsi0-0-0-2' for drive
>
> I did see that others in the past have gotten around this issue by
> rebooting the Backup-Appliance-VM and then continuing on with the next VM
> backup and looping through backup-reboot-backup-reboot-etc.
>
> Anyone have an idea on how to solve this issue and remove the hooks from
> the guest OS?
>
> Steps to reproduce this issue:
>
>
>    1. Create a backup appliance VM to be used for the backup script
>    execution
>    2. Currently I have the Vms set to virtio with threaded I/O enabled.
>    Also tried virtio_scsi with same result.
>    3. Using REST API – make snapshot of target VM
>    4. Using REST API – fetch vm metadata
>    5. Using REST API – attach the snapshot/disk to the Backup-Appliance-VM
>    6. dd the drive to backup folder
>    7. Using REST API – remove the disk from the Backup-Appliance-VM
>    8. Using REST API – delete the snapshot
>    9. ** Check the guest OS of the Backup-Appliance-VM and the mounted
>    drive from the backup above still appears and behaves as mentioned in
>    comments above.
>
>
>
— There are many details missing, including versions of everything used,
but logs would be most helpful here.

Versions for oVirt are all the most recent. This is a fresh install of the
Hosted Engine. I will just script the backup to cycle through sdb, sdc,
sdd, …. Szzzz, just seems odd that once a disk is detached and a snapshot
deleted, that the Backup_appliance-VM can still access the drive/snapshot?


Unrelated note - do NOT use /dev/sdX to enumerate them. Especially on SCSI
bus, probing is done in parallel and they may have a different name next
time. Use /dev/disk/by-id paths.



A second issue is that the above wont work when I have the Vms running on
> MPIO iSCSI storage, so for testing I have moved to NFS4. Anyone have ideas
> about either issue, I’d love to hear ;)
>

— Same - logs would be helpful here.

I will continue to dig through this issue and will post logs if stuck. I
just wanted to know if there was anything obvious that I should be doing
differently with iSCSI vs NFS with mounting disks/snapshots.


Nope.
Y.


Zip

— Y.


>
> Thanks
>
> Irc.oftc.net #ovirt
> zipur
>
>
>
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