HP-UX System Administrator's Guide: Routine Management Tasks

Adding a Mirror to an Existing Logical Volume Using Strict Mirroring
For detailed discussion of mirroring and allocation policies see “Creating and Modifying
Mirrored Logical Volumes” in the HP-UX System Administrator’s Guide: Logical Volume
Management. The following example uses HP SMH.
HP recommends that you use strict mirroring because it keeps the “mirror” data on a
separate disk from the original data. This free space must be on a disk or disks not
currently used by the file system you want to mirror. If you enable the “enforce strict
mirroring “ feature, a mirror copy will not be created unless this condition can be met.
Mirroring allocation policy can be set during the logical volume creation process or by
modifying the allocation setting of an existing logical volume.
1. Decide how many mirror copies you want. For the purposes of this example, we’ll
assume you want one mirror and the size of the volume is 500MB. There will be
two copies of the data, the original and a mirror copy.
2. Access the HP SMH Homepage.
3. Select Tools, Disks and File Systems, Logical Volumes. A list of logical volumes
will be displayed.
4. Select the logical volume you want to mirror. This will display detailed information
about the selected logical volume at the bottom of the page. Make sure the
Properties tab of the Detailed View display is selected. Check to see that the
Allocation State is set to the desired strict selection.
5. Enter the number of mirrored data images desired (in this example one), and
desired options. Since you are using strict mirroring you can let the HP SMH select
the location for the mirror data. You can place the mirrored Logical Volume on a
different physical drive by clicking on Select PV(s)... This will display available
drives. Click Add.
6. If you need to change the allocation setting, click on the Modify LV ... action on
the right side of the page, and select the desired allocation policy.
7. If the allocation setting is correct, click on the Add Mirror(s) ... action on the right
side of the page. This will display the Add Mirror(s) page.
8. Enter the number of mirrors desired (in this example, one) and select whether you
want HP SMH to make the physical volume allocation or you want to manually
select the physical volume. If you want to select the physical volume, click on the
Select PV(s) button to view available devices and make a manual selection. After
making a selection the Add Mirror(s) page is again displayed.
9. Click on the Add button. If all of the conditions specified (additional disks, free
memory, etc.) can be met, the new mirror will be created. If not, the process will
terminate with an error message.
110 Managing Systems