Managing System Dump Devices on AIX ( lg_dumplv )

http://www-01.ibm.com/support/docview.wss?uid=isg3T1000169

How to create a dedicated dump device

1. View an estimate of the dump size, enter:

   sysdumpdev -e
   

   You should see information similar to the following:
   

   0453-041 Estimated dump size in bytes: 25103360
   

2. View the PP size, enter:

   lsvg rootvg
   

   You should see information similar to the following:
   

   VOLUME GROUP:   rootvg          VG IDENTIFIER:  0000003173650c77
   VG STATE:       active          PP SIZE:        4 megabyte(s)
   VG PERMISSION:  read/write      TOTAL PPs:      479 (1916 megabytes)
   MAX LVs:        256         FREE PPs:       258 (1032 megabytes)
   LVs:            11  USED PPs:       221 (884 megabytes)
   OPEN LVs:       10  QUORUM:         2
   TOTAL PVs:      1  VG DESCRIPTORS: 2
   STALE PVs:      0  STALE PPs       0
   ACTIVE PVs:     1  AUTO ON:        yes
   

3. Determine necessary number of PPs (physical partitions). Divide the estimated size (sysdumpdev -e), by the PP size to estimate the proper number of PPs that the dump logical volume should have.
4. Determine where you have free PPs, enter:

   lsvg -p rootvg
   

   You should see information similar to the following:
   

   rootvg:
   PV_NAME           PV STATE    TOTAL PPs   FREE PPs    FREE DISTRIBUTION
   hdisk1             active       479         258       78..02..00..82..96
   hdisk2             active       159          0        00..00..00..00..00
   hdisk3             active        75          8        00..00..00..00..08
   

   NOTE: You should use the hdisk with the highest number of free PPs (in this example hdisk1).
   
5. Create a LV, enter:

   mklv -y dumplv -t sysdump rootvg 7 hdisk1 
   

6. Set LV as the dump device, enter:

   sysdumpdev -Pp /dev/dumplv
   

   You should see information similar to the following:
   

   primary              /dev/dumplv
   secondary            /dev/sysdumpnull
   copy directory       /var/adm/ras
   forced copy flag     TRUE
   always allow dump    FALSE
   

7. Change always allow dump to TRUE, enter:

   sysdumpdev -K
   

8. Verify that the flag has been changed, enter:

   sysdumpdev -l
   

   You should see information similar to the following:
   

   primary              /dev/dumplv
   secondary            /dev/sysdumpnull
   copy directory       /var/adm/ras
   forced copy flag     TRUE
   always allow dump    TRUE