How to Create a LUN

Use this procedure to create a logical unit number (LUN) from unassigned disk drives or remaining capacity. For information about LUN administration, see the Sun StorEdge RAID Manager Release Notes.

This product supports the use of hardware RAID and host-based software RAID. For host-based software RAID, this product supports RAID levels 0+1 and 1+0.

You must use hardware RAID for Oracle RAC data stored on the storage array. Do not place RAC data under volume management control. You must place all non-RAC data that is stored on the storage arrays under volume management control. Use either hardware RAID, host-based software RAID, or both types of RAID to manage your non-RAC data.

Hardware RAID uses the storage array's or storage system's hardware redundancy to ensure that independent hardware failures do not impact data availability. If you mirror across separate storage arrays, host-based software RAID ensures that independent hardware failures do not impact data availability when an entire storage array is offline. Although you can use hardware RAID and host-based software RAID concurrently, you need only one RAID solution to maintain a high degree of data availability.

When you use host-based software RAID with hardware RAID, the hardware RAID levels you use affect hardware maintenance. If you use hardware RAID level 1, 3, or 5, you can perform most maintenance procedures without volume management disruptions. If you use hardware RAID level 0, some maintenance procedures require additional volume management administration because the availability of the LUNs is impacted.

Before You Begin

This procedure provides the long forms of the Sun Cluster commands. Most commands also have short forms. Except for the forms of the command names, the commands are identical. For a list of the commands and their short forms, see Appendix A, Sun Cluster Object-Oriented Commands, in Sun Cluster 3.1 - 3.2 Hardware Administration Manual for Solaris OS.

To perform this procedure, become superuser or assume a role that provides solaris.cluster.read and solaris.cluster.modify RBAC authorization.

1. With all nodes booted and attached to the storage array or storage system, create the LUN on one node.

   After the LUN formatting completes, a logical name for the new LUN appears in /dev/rdsk on all nodes. These nodes are attached to the storage array or storage system.

   If the following SCSI warning is displayed, ignore the message. Continue with the next step.

   ... corrupt label - wrong magic number

   For the procedure about how to create a LUN, refer to your storage device's documentation. Use the format(1M) command to verify Solaris logical device names.

2. Copy the /etc/raid/rdac_address file from the node on which you created the LUN to the other node. If you copy this file to the other node, you ensure consistency across both nodes.

3. Ensure that the new logical name for the LUN that you created appears in the /dev/rdsk directory on both nodes.

   # /etc/raid/bin/hot_add

4. On one node, update the global device namespace.

   • If you are using Sun Cluster 3.2, use the following command:

     # cldevice populate

   • If you are using Sun Cluster 3.1, use the following command:

     # scgdevs

5. Ensure that the device ID numbers for the LUNs are the same on both nodes. In the sample output that follows, the device ID numbers are different.

   For an example of output indicating that the ID numbers have not been properly updated, see Example 1–1.

   • If you are using Sun Cluster 3.2, use the following command:

     # cldevice show

   • If you are using Sun Cluster 3.1, use the following command:

     # scdidadm -L

6. If the device ID numbers that you received from running the cldevice show or scdidadm command in Step 5 are the same for both nodes, proceed to Step 8.

7. If the device ID numbers that you received from running the cldevice show or scdidadm command are different, perform the procedure in How to Correct Mismatched Device ID Numbers before you proceed to Step 8 of this procedure.

8. (A1000 Only) If you want a volume manager to manage the new LUN, incorporate the new LUN into a diskset or disk group.

   For more information, see your Solaris Volume Manager or Veritas Volume Manager documentation.

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   Note –

   The StorEdge A3500 system does not support using LUNs as quorum devices.

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Example 1–1 Verifying the Device IDs

Step 5 in the preceding procedure directs you to verify that the device ID numbers for the LUNs are the same on both nodes. In the sample output that follows, the device ID numbers are different.

# cldevice show 
... 
DID Device Name:                            /dev/did/rdsk/d3
  Full Device Path:                            phys-schost-2:/dev/rdsk/c1t3d0
  Full Device Path:                            phys-schost-1:/dev/rdsk/c1t3d1
  Replication:                                 none
  default_fencing:                             global