Known Issues

iSCSI multipath and Cinder backup issue

Affected versions

  • NexentaStor 5+
  • OpenStack Mitaka+

Description

Openstack Nova provides the ability to use iSCSI Multipath, but Cinder Backup does not supports iSCSI Multipath. Therefore Cinder Backup can fail in some conditions. For example in case of backup attached Cinder iSCSI volume on the Nova Compute host.

Rate-limit volume copy bandwidth and NFS backend

Affected versions

  • NexentaStor 4+ and NexentaStor 5+
  • OpenStack Juno+

Description

When OpenStack administrator create a new volume from an image or an existing volume, or when OpenStack administrator upload a volume image to the Image service, large data copy may stress disk and network bandwidth. To mitigate slow down of data access from the instances, OpenStack Block Storage supports rate-limiting of volume data copy bandwidth. This feature requires libcgroup to set up blkio cgroup for disk I/O bandwidth limit. The libcgroup is provided by the cgroup-bin package in Debian and Ubuntu, or by the libcgroup-tools package in Fedora, Red Hat Enterprise Linux, CentOS, openSUSE, and SUSE Linux Enterprise. But some backends which use remote file systems such as NFS are not supported by this feature.

Generic volume migration and cloned volumes

Affected versions

  • NexentaStor 4+ and NexentaStor 5+
  • Openstack Newton and previous

Description

Steps:

  • Create a new Cinder volume from an existing Cinder volume
  • Or create a new Cinder volume from an existing Cinder snapshot
  • Try to migrate or retype the created Cinder volume to another volume host

During generic volume retype/migration, Cinder attempts to create a new temporary volume at the destination backend as a clone from a nonexistent snapshot and the operation fails.

Workaround

Reset source volume/snapshot ID for the migrated volume before migrate or retype operation:

$ mysql cinder
mysql> update volumes set snapshot_id=NULL where id="${Volume_ID}";
mysql> update volumes set source_volid=NULL where id="${Volume_ID}";