A separate paging device is required for each LPAR that uses shared memory. One of the following device types can be used as a paging device:

• • logical volume
  • local disk
  • SAN LUN
  • iSCSI LUN

If two redundant paging virtual I/O servers are used, the paging devices must be SAN LUNs.

On our virtual I/O server ms03-vio1, the following physical volumes exist:

$ vios lspv ms03-vio1
PVNAME  PVID              VGNAME  PVSTATE
hdisk0  0000000000cafe00  None    -
hdisk1  0000000000cafe01  rootvg  active
hdisk2  0000000000cafe02  rootvg  active
hdisk3  0000000000cafe03  None    -
hdisk4  0000000000cafe04  None    -
$

The physical volumes hdisk3 and hdisk4 are each SAN LUNs, as the “vios lsdev” command shows:

$ vios lsdev ms03-vio1 hdisk3
NAME    STATUS     PHYSLOC                                          PARENT  DESCRIPTION
hdisk3  Available  U78AA.001.VYRGU0Q-P1-C5-T1-W500507680130A1C4-L0  fscsi4  MPIO IBM 2145 FC Disk
$
$ vios lsdev ms03-vio1 hdisk4
NAME    STATUS     PHYSLOC                                          PARENT  DESCRIPTION
hdisk3  Available  U78AA.001.VYRGU0Q-P1-C5-T1-W50050768013098BC-L0  fscsi4  MPIO IBM 2145 FC Disk
$

These SAN LUNs have not yet been used and are therefore perfect candidates as paging devices. There are 2 different but equivalent commands to add a paging device to a shared memory pool. Either the command “ms addpgdev” (add paging device) can be used:

$ ms addpgdev ms03 ms03-vio1 hdisk3
$

In addition to the managed system, the paging virtual I/O server and the paging device must be specified as arguments.

Alternatively, the somewhat shorter command “vios addpgdev” can be used:

$ vios addpgdev ms03-vio1 hdisk4
$

In which case only the paging virtual I/O server and the paging device have to be specified.

The shared memory pool now has the first two paging devices, as the command “ms lspgdev“ shows:

$ ms lspgdev ms03
                                                                REDUNDANT                                    
MS_NAME  DEVICE_NAME  PAGING_VIOS_NAME  STATE     DEVICE_NAME  PAGING_VIOS_NAME  STATE  SIZE   TYPE  LPAR_ID
ms03     hdisk3       ms03-vio1         Inactive  -            -                 -      51200  phys  none
ms03     hdisk4       ms03-vio1         Inactive  -            -                 -      51200  phys  none
$