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Additional mirroring considerations

The larger private region size that was introduced in VxVM 3.2 (1MB) and VxVM 5.0 (32MB) may create one of the following mirroring scenarios under which vxdiskadm fails:

• Mirroring a full root disk to a target disk which is exactly the same size as the source disk. A full disk means a disk that has no free cylinders.
• Mirroring a disk created using an earlier version of Veritas Volume Manager to a target disk which is exactly the same size as the source disk. You only need to use this step if mirroring using vxdiskadm fails.
• Mirroring a full Veritas Volume Manager disk (not a root disk) that was encapsulated in VxVM 3.5 to a target disk that is the same size as the source disk. You only need to use this step if mirroring using vxdiskadm fails.

  See the vxdiskadm(1M) manual page.

 To create a mirror under any of these scenarios

1. Determine the size of the source disk's private region, using either of the following methods:
   • If the source disk is a root disk, obtain its private region length by running this command:

     # vxprint -l rootdisk

     The disk media name of the root disk is typically rootdisk.

     In the output, find the privlen value. In this example, the value is 3071:

     devinfo: publen=39846240 privlen=3071

   • If the source disk is not a root disk, obtain its private region length by running this command:

     # vxdisk list diskname

     where diskname is the disk media name of the source disk.

     In the displayed output, note the len value for the private field. In this example, the value of this field is 3071:

     private: slice=4 offset=1 len=3071

2. Use the vxdisksetup program to initialize the target disk:

   # /usr/lib/vxvm/bin/vxdisksetup -i c#t#d# privoffset=0 \

     privlen=XXXX publen=YYYY

   where XXXX is the size of the source disk's private region, and YYYY is the size of its public region.

   If your system is configured to use enclosure-based naming instead of OS-based naming, replace the c#t#d# name with the enclosure-based name for the disk.

3. Add the newly initialized target disk to the source disk group:

   '# vxdg -g diskgroup adddisk medianame=c#t#d#

4. Use the vxdiskadm command and choose item 6 (Mirror volumes on a disk) to create the mirror. Specify the disk media names of the source disk (rootdisk) and the target disk (medianame).