Managing LUNs and LUN maps
Tasks to manage LUNs and LUN maps
You can use the command-line interface or FilerView to
- Control block protocol access
- Unmap a LUN from an igroup
- Rename a LUN
- Modify the LUN description
- Modify a LUN's serial number
- Enable or disable space reservations
- Remove a LUN
- Access a LUN with NAS protocols
Controlling block protocol access
The lun online and lun offline commands enable and disable block protocol accesses while preserving mappings.
Bringing a LUN online
To bring one or more LUNs online, complete the following step.
Step
|
Action
|
|---|
|
1 |
Enter the following command:
lun online lun-path [lun-path ...]
Example
lun online /vol/vol1/lun0
|
Taking a LUN offline
Taking a LUN offline makes it unavailable for block protocol access; however, you can write to an offline LUN using NAS protocols. To take a LUN offline, complete the following step.
Step
|
Action
|
|---|
|
1 |
Enter the following command:
lun offline lun-path [lun-path ...]
Example
lun offline /vol/vol1/lun0
|
Unmapping a LUN from an igroup
To remove the mapping of a LUN from an igroup, complete the following steps.
Step
|
Action
|
|---|
|
1 |
Enter the following command:
lun offline lun-path
Example
lun offline /vol/vol1/lun1
|
|
2 |
Enter the following command:
lun unmap lun-path igroup LUN_ID
Example
lun unmap /vol/vol1/lun1 solaris-igroup0 0
|
Renaming a LUN
To rename a LUN, completing the following step.
Step
|
Action
|
|---|
|
1 |
Enter the following command:
lun move lun_path new_lun_path
Example
lun move /vol/vol1/mylun /vol/vol1/mynewlun
Note
The existing lun_path and the new lun_path must be in the same qtree. |
Resizing a LUN
You can increase or decrease the size of a LUN; however, the host operating system must be able to recognize changes to its disk partitions.
Restrictions on resizing a LUN
The following restrictions apply:
- On Windows, resizing is only supported on basic disks. Resizing is not supported on dynamic disks.
- On Solaris, decreasing the LUN size is not supported. Only increasing the LUN size is supported.
On Solaris, if you are running VxVM, resizing LUNs is not supported.
If you want to increase the size of the LUN, the SCSI disk geometry imposes an upper limit for how large a LUN can be resized, and Data ONTAP imposes a maximum increase of 2 TB, in 1 MB increments.
To change the size a LUN, complete the following steps.
Caution
Before resizing a LUN, ensure that this feature is compatible with the host operating system.
Step
|
Action
|
|---|
|
1 |
Take a LUN offline before resizing it by entering the following command:
lun offline lun-path
Example
lun offline /vol/vol1/qtree/lun2
|
|
2 |
Change the size of the LUN by entering the following command:
lun resize [-f] lun-path new-size
-f overrides warnings when decreasing the size of the LUN.
Example
(Assuming that lun2 is 5 GB and you are increasing it to 10 GB
lun resize /vol/vol1/qtree1/lun2 10g
|
|
3 |
From the host, rescan or rediscover the LUN so that the new size is recognized.
Example
For Solaris hosts, use Solaris commands to erase the disk label and create a new one, and then use the Solaris mkfs command to increase the file system on the disk slice to fill the newly enlarged slice.
|
Modifying the LUN description
To modify the LUN description, complete the following step.
Step
|
Action
|
|---|
|
1 |
Enter the following command:
lun comment lun-path [comment]
Example
lun comment /vol/vol1/lun2 "10GB for payroll records"
Note
If you use spaces in the comment, enclose the comment in quotation marks. |
Modifying a LUN's serial number
To modify a LUN's serial number, complete the following steps.
Step
|
Action
|
|---|
|
1 |
Take the LUN offline by entering the following command:
lun offline lun-path
Example
lun offline /vol/vol1/qtree1/lun2
|
|
2 |
Modify the LUN's serial number by entering the following command:
lun serial lun-path new-serial-number
Example
lun serial /vol/vol1/qtree1/lun2 OcmePIdQxjcH
|
Enabling or disabling space reservations for LUNs
To enable or disable space reservations for a LUN, complete the following step.
Caution
If you disable space reservations, you might experience write failures due to insufficient disk space. When this occurs, Data ONTAP displays system messages (one message per file) on the console, or sends these messages to log files and other remote systems, as specified by its /etc/syslog.conf configuration file.
Step
|
Action
|
|---|
|
1 |
Enter the following command:
lun set reservation lun_path [enable|disable]
lun_path is the LUN in which space reservations are to be set. This must be an existing LUN.
Note
Enabling space reservation on a LUN fails if there is not enough free space in the volume for the new reservation. |
Removing a LUN
To remove one or more LUNs, complete the following step.
Step
|
Action
|
|---|
|
1 |
Remove one or more LUNs by entering the following command:
lun destroy [-f] lun-path [lun-path ...]
-f forces the lun destroy command to execute even if the LUNs specified by one or more lun-paths are mapped or are online.
Without the -f parameter, you must first take the LUN offline and unmap it, and then enter the lun destroy command.
|
Accessing a LUN with NAS protocols
When you create a LUN, it can only be accessed with the iSCSI protocol by default. However, you can make a LUN available to a host using NAS protocols if NAS protocols are licensed and enabled on the filer. The usefulness of accessing a LUN over NAS protocols is host application-dependent.
Note
A LUN cannot be extended or truncated using NFS or CIFS protocols.
If you want to write to a LUN over NAS protocols, you must take the LUN offline or unmap it to prevent overwriting data in the LUN using the iSCSI protocol. To make a LUN accessible to a host using a NAS protocol, complete the following steps.
Step
|
Action
|
|---|
|
1 |
Determine whether you want to read or write to the LUN over the NAS protocol and take appropriate action:
- If you want read access, the LUN can remain online.
- If you want write access, ensure that the LUN is offline or unmapped.
|
|
2 |
Enter the following command:
lun share lun-path {none|read|write|all}
Example
lun share /vol/vol1/qtree1/lun2 read
Result
The LUN is now readable over NAS.
|
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reserved.
Part No. 210-00571
File: c3lun-i2.htm
Last updated: 11/21/03 17:05:22