Modifying the RAID type for a volume

Changing the RAID group type

You can change the type of RAID protection configured for a volume. When you change a volume's RAID type, Data ONTAP reconfigures all the existing RAID groups to the new type and applies the new type to all subsequently created RAID groups in that volume.

Changing from RAID 4 to RAID DP protection

When you change a volume's RAID protection from RAID 4 to RAID DP, you first need to ensure that hot spare disks of sufficient number and size exist on that volume's filer, because during the conversion, Data ONTAP adds an additional disk to each existing RAID group from the filer's hot spare disk pool and assigns the new disk the dParity disk function for the RAID DP group. In addition, the volume's raidsize option, which controls the size of new RAID groups that might be created in the volume, is modified to RAID DP defaults on this appliance.

To change an existing volume's RAID protection from RAID 4 to RAID DP, complete the following steps.

Step	Action
1	Determine the number of RAID groups and the size of their parity disks in the volume in question by issuing the following command. *vol status volname* -r**
2	Issue the following command to make sure that a hot spare disk exists on the filer for each RAID group listed for the volume in question, and make sure that these hot spare disks match the size and checksum type of the existing parity disks in those RAID groups. vol status -s If necessary, add hot spare disks of the appropriate number of appropriate number and size and checksum type to the filer. See Adding new disks to the filer.
3	Enter the following command: vol options vol-name raidtype raid_dp vol-name is the volume whose RAID type you are changing. Example The following command changes the RAID type of the volume thisvol to RAID DP: vol options thisvol raidtype raid_dp

Step

Action

Determine the number of RAID groups and the size of their parity disks in the volume in question by issuing the following command.

vol status volname -r

Issue the following command to make sure that a hot spare disk exists on the filer for each RAID group listed for the volume in question, and make sure that these hot spare disks match the size and checksum type of the existing parity disks in those RAID groups.

vol status -s

If necessary, add hot spare disks of the appropriate number of appropriate number and size and checksum type to the filer. See Adding new disks to the filer.

Enter the following command:

vol options vol-name raidtype raid_dp

vol-name is the volume whose RAID type you are changing.

Example

The following command changes the RAID type of the volume thisvol to RAID DP:

vol options thisvol raidtype raid_dp

Associated RAID group size changes

When you change the RAID protection of an existing volume from RAID 4 to RAID DP, the following associated RAID group size changes take place:

A second parity disk (dParity) is automatically added to each existing RAID group from the hot spare disk pool, thus increasing the size of each existing RAID group by one.
Note
If hot spare disks of insufficient number or size to support the RAID type conversion are available on the filer, Data ONTAP will issue a warning before executing the vol options volname raidtype raid_dp command. If you continue the operation, RAID DP protection will be implemented on the volume in question, but some of its RAID groups for which no second parity disk was available will remain degraded. The protection will be no improvement over RAID 4, and no hot spare disks will be available in case of disk failure since all were reassigned as dParity disks.
The volume's raidsize option, which sets the size for any new RAID groups created in this volume, is automatically reset to one of the following RAID DP defaults: on all non-NearStore appliances, 16; on an R100 appliance, 12; on an R150 platform, 14.
Note
After the vol options volname raidtype raid_dp operation is complete, you can manually change the raidsize option through the vol options volname raidsize command. See Changing the size of the most recent and future RAID groups.

Changing from RAID DP to RAID 4 protection

To change the an existing volume's RAID protection from RAID DP to RAID 4, complete the following step.

Step	Action
1	Enter the following command: vol options vol-name raidtype raid4 vol-name is the volume whose RAID type you are changing. Example The following command changes the RAID type of the volume thatvol to RAID 4: vol options thatvol raidtype raid4

Associated RAID group size changes

When you change the RAID protection of an existing volume from RAID DP to RAID 4, Data ONTAP automatically carries out the following associated RAID group size changes:

In each of the volume's existing RAID groups, the RAID DP second parity disk (dParity) is removed and placed in the hot spare disk pool, thus reducing each RAID group's size by one.
On NearStore appliances, Data ONTAP changes the volume's raidsize option, which determines the size of any new RAID group created in this volume, to the RAID 4 default size on the NearStore R100 (8) or R150 (6) platforms.
On non-NearStore appliances, Data ONTAP usually changes the setting for the volume's raidsize option, which determines the size of any new RAID group created in this volume, to the size of the largest RAID group in the volume.
Exceptions are the following cases: if the volume's largest RAID group is larger than the maximum RAID 4 group size on non-NearStore platforms (14), then the volume's raidsize option will be set to 14; if the volume's largest RAID group is smaller than the default RAID 4 group size on non-NearStore platforms (8), then the volume's raidsize option will be set to 8.

Note
After the vol options volname raidtype raid_dp operation is complete, you can change the raidsize setting through the vol options volname raidsize command. See Changing the size of the most recent and future RAID groups.

Verifying the RAID type

To verify the RAID type of a volume, enter the vol options vol_name or vol status vol_name command.