After you create your LUNs, you can manage them in a number of different ways. For example, you can control LUN availability, unmap a LUN from an igroup, delete a LUN, and rename a LUN.
You can use the command-line interface (CLI) to manage LUNs.
Controlling LUN availability
You can use the lun online and lun offline commands to control the availability of LUNs while preserving the LUN mappings.
Moving LUNs
You can use the lun move command to rename or move a LUN.
Modifying LUN descriptions
You may have added a LUN description when creating the LUN. You can use the lun comment command to modify that description or add a new one.
How LUN reservations work
When reservations are enabled for one or more LUNs, Data ONTAP reserves enough space in the volume so that writes to those LUNs do not fail because of a lack of disk space.
Accessing LUNs with NAS protocols
When you create a LUN, you can only access it with the iSCSI, FC, or FCoE protocol by default. However, you can use NAS protocols to make a LUN available to a host if the NAS protocols are licensed and enabled on the storage system.
Displaying LUN serial numbers
A LUN serial number is a unique, 12-byte, ASCII string generated by the storage system. Many multipathing software packages use this serial number to identify redundant paths to the same LUN.
Displaying LUN statistics
You can use the lun stats command to display the number of read and write operations and the number of operations per second for LUNs.
Displaying LUN mapping information
You can use the lun show -m command to display a list of LUNs and the hosts to which they are mapped.
Displaying detailed LUN information
You can use the lun show -v command to show additional LUN details, such as the serial number, ostype (multiprotocol type), and maps.
Displaying hidden staging area LUNs
You can use the lun show staging command to obtain a list of all the hidden staging area LUNs. If you want to destroy an igroup to which the staging LUN is mapped, the lun show staging command indicates the reason for not being able to destroy an igroup.
LUN alignment in virtual environments
LUN alignment problems, which can lead to lower performance for your storage system, are common in virtualized server environments. To avoid LUN alignment problems, it is essential to follow best practices for proper LUN alignment.
Removing LUNs
You can use the lun destroy command to remove one or more LUNs.
Misaligned I/O can occur on properly aligned LUNs
Data ONTAP can report alignment problems with properly aligned LUNs. A certain amount of misaligned I/O occurs on properly aligned LUNs and can be harmless.