Thursday, January 16, 2014

How to map a snapshot of a LUN to another server for backup

You would like to map the Data OnTap snapshot of a LUN to another server as a LUN to be used for daily/weekly backups to tape over Fiber Channel or iSCSI.  This scenario is commonly referred to as off-host backup.

To obtain a consistent snapshot you must use the SnapDrive or SnapManager products from Netapp to create the snapshot of the desired LUN.  Then on the off-host backup server you can use SnapDrive to mount the snapshot as a LUN.

SnapDrive mounts the snapshot of the LUN as a Read/Write Clone LUN, not as Read Only, but changes to the snapshot LUN are deleted once the LUN is deleted.

As an alternative you can create an inconsistent snapshot on the Netapp Controller use that snapshot as the foundation of a LUN Clone.

Here are the commands to run on the Netapp Controller to take any existing snapshot and create a LUN Clone

1)      Optional, create a new snap to be used as the basis of the LUN clone
snap create volume snap_name

2)      Create the lun clone, in the same volume as existing lun, using existing snap
lun clone create /vol/volume/clone01 -b /vol/volume/lun01 snap_name

a.       If you get the following error lun clone create: No space left on device use the following syntax
lun clone create /vol/volume/clone01 -o noreserve -b /vol/volume/lun01 snap_name

3)      Mount the clone to the off-host backup server.
lun map /vol/volume/clone01 backup_igroup #

backup_igroup = the initiator group associated with the backup server.
# = the LUN ID to mount the LUN as

a.       You could use SnapDrive to mount the LUN to the off-host backup server, as an alternative.
4)      On the backup server rescan your drives
5)      Bring the new volume on-line
6)      Perform the backup
7)      Take the volume off-line
8)      Remove the clone from the off-host backup server
lun unmap /vol/volume/clone01 backup_igroup

backup_igroup = the initiator group associated with the backup server

9)      Remove the clone
lun destroy /vol/volume/clone01

No comments:

Post a Comment