On Jan 22, 2018 5:32 PM, "Zip" <plord@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

zipur



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