Extend dump devices in AIX

If you see a message in AIX like this:

LABEL:          DMPCHK_TOOSMALL
IDENTIFIER:     E87EF1BE

Date/Time:       Sun Jun  1 12:00:00 GMT+00:00 2012
Sequence Number: 182200
Machine Id:      XXXXXXXXXXXX
Node Id:         db03
Class:           O
Type:            PEND
WPAR:            Global
Resource Name:   dumpcheck

Description
The largest dump device is too small.

Then you need to resize your dump devices. First check the devices which are used as dump devices:

# sysdumpdev -l
primary              /dev/lg_dumplv
secondary            /dev/lg_dumplv2
copy directory       /var/adm/ras
forced copy flag     TRUE
always allow dump    FALSE
dump compression     ON
type of dump         traditional

The above output shows /dev/lg_dumplv and /dev/lg_dumplv2 as dump devices. Next check the estimated dump size which is needed:

# sysdumpdev -e
0453-041 Estimated dump size in bytes: 9665773568

Dividing 9665773568 bytes three time by 1024 shows the correct size in GB:

# echo 9665773568/1024/1024/1024 | bc -l
9.00195312500000000000

According to the above output 9GB is needed. To resize the dump devices you need the size of your PP's:

# lsvg rootvg
...
VG STATE:        active                PP SIZE:     512 megabyte(s)
...

512MB per PP, keep that value in mind. Now begin to resize the dump devices. First check the current size for your dump devices:

# lsvg -l rootvg
rootvg:
LV NAME             TYPE       LPs     PPs     PVs  LV STATE      MOUNT POINT
...
lg_dumplv           sysdump    8       8       1    open/syncd    N/A
lg_dumplv2          sysdump    8       8       1    open/syncd    N/A
...

Each dump device is 8 PP's in size, that means 8PP's multiplied by 512MB equals 4096MB (or 4GB), but 9GB are needed. In this case 5GB are needed - or at least 10 PP's. To extend the dump devices use extendlv:

# extendlv lg_dumplv 12
# extendlv lg_dumplv2 12

I used 12 PP's instead of only 10 PP's to have a little space left. Now check the sizes of the dump devices again:

# lsvg -l rootvg | grep lg_dumplv
lg_dumplv           sysdump    20      20      1    open/syncd    N/A
lg_dumplv2          sysdump    20      20      2    open/syncd    N/A

20PP's multiplied by 512MB equals 10GB which is enough for 9GB.