Dynamic Multi-Pathing 7.4.1 Administrator's Guide - AIX

To configure DMP support for booting over a SAN

1. Verify that each path to the root device has the same physical volume identifier (PVID) and the same volume group. Use the lspv command for the root volume group to verify that the PVID and volume group entries are set correctly. The PVID and volume group entries in the second and third columns of the output should be identical for all the paths.

   In this example, the LVM root disk is multi-pathed with four paths. The output from the lspv command for the root volume group (rootvg) is as follows:

   # lspv | grep rootvg
   hdisk374 00cbf5ce56def54d rootvg active
   hdisk375 00cbf5ce56def54d rootvg active
   hdisk376 00cbf5ce56def54d rootvg active
   hdisk377 00cbf5ce56def54d rootvg active

2. If the PVID and volume group entries are not set correctly on any of the paths, use the chdev command to set the correct value.

   For example, the following output shows that the hdisk377 path is not set correctly:

   # lspv
   hdisk374 00cbf5ce56def54d rootvg active
   hdisk375 00cbf5ce56def54d rootvg active
   hdisk376 00cbf5ce56def54d rootvg active
   hdisk377 none             None

   To set the PVID for the path, use the following command:

   # chdev -l hdisk377 -a pv=yes
   hdisk377 changed

   The output of the lspv command now shows the correct values:

   # lspv | grep rootvg
   hdisk374 00cbf5ce56def54d rootvg active
   hdisk375 00cbf5ce56def54d rootvg active
   hdisk376 00cbf5ce56def54d rootvg active
   hdisk377 00cbf5ce56def54d rootvg active

3. If any path to the target disk has SCSI reserve ODM attribute set, then change the attributes to release the SCSI reservation from the paths, on a restart.

   • If a path has the reserve_policy attribute set, change thereserve_policy attribute to no_reserve for all the paths.

     # lsattr -E1 hdisk557 | grep res

     reserve_policy single_path

     Reserve Policy True

     # chdev -l hdisk557 -a reserve_policy=no_reserve -P

     hdisk557 changed

   • If a path has the reserve_lock attribute set, change the reserve_lockattribute to no.

     #  lsattr -E1 hdisk558 | grep reserve_lock

     reserve_lock yes

     Reserve Device on open True

     # chdev -l hdisk558 -a reserve_lock=no -P

     hdisk558 changed

4. Set the boot list to include all the paths of current boot disk.

   # bootlist -m normal hdisk374 hdisk375 hdisk376 hdisk377 blv=hd5

   Verify that the boot list includes all paths and that each path shows the default boot volume hd5:

   # bootlist -m normal -o
   hdisk374 blv=hd5
   hdisk375 blv=hd5
   hdisk376 blv=hd5
   hdisk377 blv=hd5

5. If the blv option is not set for a path to the disk, use the bootlist command to set it. For example:

   # bootlist -m normal hdisk374 hdisk375 hdisk376 hdisk377 blv=hd5

6. Run one of the following commands to configure DMP on the root disk:

   • The recommended method is to turn on DMP support for LVM volumes, including the root volume.

     # vxdmpadm settune dmp_native_support=on

   • The following command enables DMP support for LVM volumes only for the root disk.

     # vxdmpadm native enable vgname=rootvg

7. Reboot the system. DMP takes control of the SAN boot device to perform load balancing and failover.
8. Verify whether DMP controls the root disk.

   # vxdmpadm native list vgname=rootvg
   PATH           DMPNODENAME
   ===========================
   hdisk374       ams_wms0_491
   hdisk375       ams_wms0_491
   hdisk376       ams_wms0_491
   hdisk377       ams_wms0_491

   # lspv | grep rootvg
   hdisk374 00cbf5ce56def54d rootvg active
   hdisk375 00cbf5ce56def54d rootvg active
   hdisk376 00cbf5ce56def54d rootvg active
   hdisk377 00cbf5ce56def54d rootvg active