Methods of creating LUNs

About creating LUNs

There are several ways to create a LUN, but whichever method you choose, you create a LUN by specifying the following attributes:

The path name of the LUN
The path name must be at the root level of a qtree or a volume that specifies where the LUN is located. Example: /vol/vol1/lun1.

Note
You might find it useful to provide a meaningful path name, one that describes how the LUN is used, such as the name of an application or the kind of data that is stored in the LUN, or the user's name who has exclusive or primary use of the data stored in the LUN.
The type of operating system running on the host that accesses the LUN
- The values are default, solaris, and windows.
  default indicates that the contents of the LUN are not specified.
  
  solaris indicates that the LUN stores a Solaris raw disk in a single-slice partition.
  
  windows indicates that the LUN stores a raw disk device in a single-partition Windows disk.
  
  linux indicates that the LUN stores a Linux raw disk with no partition table. The linux os type uses the "solaris" style geometry, and there is no prefix or suffix. So if you intend to create a LUN from a file or access the data on the LUN using NAS, you cannot put a partition table on a LUN with the "linux" os type. For more information about creating LUNs for Linux access, see the approriate Host Attach Kit for Linux.
The size of the LUN
When you create a LUN, you specify its size as raw disk space, depending on the filer and the host. The usable space in the LUN is dependent on host or application overhead requirements. For example, partition tables and host file system metadata reduce usable space for applications. The minimum and maximum sizes for LUNs are as follows:

Operating System	Minimum	Maximum
Solaris	4MB	1023GB
Windows: Basic disk	31.5MB	2TB
Windows: Dynamic disk		1TB
Data ONTAP		2TB

You specify the size, in bytes (default), or by using the following multiplier suffixes.

Multiplier suffix	Size
c	bytes
w	words or double bytes
b	512-byte blocks
k	kilobytes
m	megabytes
g	gigabytes
t	terabytes

A brief description of the LUN (optional)
The name of the initiator group that is allowed access to the LUN
Note
You can create initiator groups that specify which initiators have access to the LUNs either before or after you create LUNs, but initiator groups must be created before you can map a LUN to an initiator group.
The LUN ID number that the initiator uses to identify and access the LUN
Whether space reservation is enabled

Methods of creating LUNs

You create LUNs using one of the following methods:

Entering the lun setup command, which prompts you through the sequence of creating a LUN, creating an initiator group, and mapping the LUN to the initiator group
Using FilerView
Entering a series of individual commands (such as lun create, igroup create, and lun map)
Note
You can create as many LUNs as Data ONTAP supports using the lun create command before mapping them to LUN IDs seen by initiator groups.
Using SnapDrive 2.0 or later for Windows
SnapDrive furnishes a user-friendly interface to manage LUNs on a filer. This product provides online storage configuration, LUN expansion, and streamlined storage management. Integrated with NetApp Snapshot functionality, it creates point-in-time images of data stored in LUNs that are connected to the filer, for backup, archiving, recovery, and asynchronous mirroring. For more information, see the appropriate SnapDrive Installation and Administration Guide for the license you purchased.

Note
If you choose to use SnapDrive, all LUN management functions must be performed using the SnapDrive interface.

Guidelines for creating LUNs

Use the following guidelines when creating LUNs:

Do not put LUNs in the /vol/vol0 root volume.
Create LUNs at the root of a qtree in a volume or at the root of the volume. You can use a naming convention to help you identify where LUNs are located, such as prepending the name of the LUNs with lun. For example: /vol/vol1/lun_host1.
Distribute LUNs across the filer cluster.