Creating Disksets

A diskset is a set of multihost disk drives containing Solstice DiskSuite objects that can be accessed exclusively (but not concurrently) by multiple hosts. To create a diskset, root must be a member of Group 14.

When creating your disksets, use the following rules to ensure correct operation of the cluster in the event of disk enclosure failure:

1. If exactly two "strings" are being used, the diskset should have the same number of physical disks on the two strings.

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   Note -

   For the two-string configuration, mediators are required. Refer to the Sun Cluster 2.2 System Administration Guide for details on setting up mediators.

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2. If more than two strings are being used, for example three strings, then you must ensure that for any two strings S1 and S2, the sum of the number of disks on those strings exceeds the number of disks on the third string S3. This is expressed as the following formula: count(S1) + count(S2) > count(S3).

How to Create a Diskset

Perform this procedure for each diskset in the cluster. All nodes in the cluster must be up. Creating a diskset involves assigning hosts and disk drives to the diskset.

1. Make sure the local metadevice state database replicas exist.

   If necessary, refer to the procedure "How to Create Local Metadevice State Database Replicas".

2. As root, create the disksets by running the metaset(1M) command from one of the cluster nodes.

   For example, this command creates two disksets, hahost1 and hahost2, consisting of nodes phys-hahost1 and phys-hahost2.

   phys-hahost1# metaset -s hahost1 -a -h phys-hahost1 phys-hahost2 phys-hahost1# metaset -s hahost2 -a -h phys-hahost1 phys-hahost2

3. Check the status of the new disksets by running the metaset(1M) command.

   phys-hahost1# metaset

   You are now ready to add drives to the diskset, as explained in the procedure "How to Add Drives to a Diskset".

How to Add Drives to a Diskset

When a drive is added to a diskset, Solstice DiskSuite repartitions it as follows so that the metadevice state database for the diskset can be placed on the drive.

• A small portion of each drive is reserved in Slice 7 for use by Solstice DiskSuite. The remainder of the space on each drive is placed into Slice 0.

• Drives are repartitioned when they are added to the diskset only if Slice 7 is not set up correctly.

• Any existing data on the disks is lost by the repartitioning.

• If Slice 7 starts at Cylinder 0, and the disk is large enough to contain a state database replica, the disk is not repartitioned.

After adding a drive to a diskset, you may repartition it as necessary, with the exception that Slice 7 is not altered in any way. Refer to "How to Repartition Drives in a Diskset", and to Chapter 2, Planning the Configuration, for recommendations on how to set up your multihost disk partitions.

If you repartition a disk manually, create a Partition 7 starting at Cylinder 0 that is large enough to hold a state database replica (approximately 2 Mbytes). The Flag field in Slice 7 must have V_UNMT (unmountable) set and must not be set to read-only. Slice 7 must not overlap with any other slice on the disk. Do this to prevent the metaset(1M) command from repartitioning the disk.

Use this procedure to add drives to a diskset.

1. Make sure you have prepared the configuration to use the DID driver, and that the disksets have been created.

   If necessary, refer to "How to Prepare the Configuration to Use the DID Driver" and "How to Create a Diskset".

2. As root, use the metaset(1M) command to add the drives to the diskset.

   Use the DID driver name for the disk drives rather than the character device name. For example:

   phys-hahost1# metaset -s hahost1 -a /dev/did/dsk/d1 /dev/did/dsk/d2 phys-hahost1# metaset -s hahost2 -a /dev/did/dsk/d3 /dev/did/dsk/d4

3. Use the metaset(1M) command to verify the status of the disksets and drives.

   phys-hahost1# metaset -s hahost1 phys-hahost1# metaset -s hahost2

4. (Optional) Refer to "Planning and Layout of Disks", to optimize multihost disk slices.