How to Create an md.tab File

Create an /etc/lvm/md.tab file for each node in the cluster.

When using Solstice DiskSuite software, ensure that local metadevices have names that are distinct from the device ID (DID) names used to form disksets. For example, if the DID name /dev/did/dsk/d3 is used in a diskset, do not use the name /dev/md/dsk/d3 in configuring local metadevices.

1. Become superuser on the cluster node.

2. List the DID mappings for reference when creating your md.tab file.

   Use the full DID pseudo-driver names in the md.tab file in place of the lower-level device names (cNtXdY).

   # scdidadm -L

   In the following example, the first column of output is the DID instance number, the second column is the full path (physical path), and the third column is the full DID pseudo-driver name (pseudo path).

   1       phys-schost-1:/dev/rdsk/c0t0d0 /dev/did/rdsk/d1 2       phys-schost-1:/dev/rdsk/c1t1d0 /dev/did/rdsk/d2 2       phys-schost-2:/dev/rdsk/c1t1d0 /dev/did/rdsk/d2 3       phys-schost-1:/dev/rdsk/c1t2d0 /dev/did/rdsk/d3 3       phys-schost-2:/dev/rdsk/c1t2d0 /dev/did/rdsk/d3 ...

3. Create an /etc/lvm/md.tab file and edit it by hand with your preferred text editor.

Refer to the Solstice DiskSuite documentation for details on creating an md.tab file.

Example--Sample md.tab File

The following sample md.tab file defines the metadevices for the diskset named dg-schost-1. The ordering of lines in the md.tab file is not important.

dg-schost-1/d0 -t dg-schost-1/d1 dg-schost-1/d4
    dg-schost-1/d1 -m dg-schost-1/d2
        dg-schost-1/d2 1 1 /dev/did/rdsk/d1s4
        dg-schost-1/d3 1 1 /dev/did/rdsk/d55s4
    dg-schost-1/d4 -m dg-schost-1/d5
        dg-schost-1/d5 1 1 /dev/did/rdsk/d3s5
        dg-schost-1/d6 1 1 /dev/did/rdsk/d57s5

The sample md.tab file is constructed as follows.

• The first line defines the trans metadevice d0 to consist of a master (UFS) metadevice d1 and a log device d4. The -t signifies this is a trans metadevice. The master and log devices are specified by their position after the -t flag.

  dg-schost-1/d0 -t dg-schost-1/d1 dg-schost-1/d4

• The second line defines the master device as a mirror of the metadevices. The -m in this definition signifies a mirror device, and one of the submirrors, d2, is associated with the mirror device, d1.

  dg-schost-1/d1 -m dg-schost-1/d2

• The fifth line similarly defines the log device, d4, as a mirror of metadevices.

  dg-schost-1/d4 -m dg-schost-1/d5

• The third line defines the first submirror of the master device, d2, as a one-way stripe.

  dg-schost-1/d2 1 1 /dev/did/rdsk/d1s4

• The fourth line defines the second submirror of the master device, d3.

  dg-schost-1/d3 1 1 /dev/did/rdsk/d55s4

• Finally, the log device submirrors, d5 and d6, are defined. In this example, simple metadevices for each submirror are created.

  dg-schost-1/d5 1 1 /dev/did/rdsk/d3s5 dg-schost-1/d6 1 1 /dev/did/rdsk/d57s5

If you have existing data on the disks that will be used for the submirrors, you must back up the data before metadevice setup and restore it onto the mirror.

Where to Go From Here

To activate the metadevices defined in the md.tab files, go to "How to Activate Metadevices".