Dump Area Information

[Filosofo]

Hello,
my question is:
What's happen when the system panic?
I would know information about dump area.
I have system whit install HP-UX 11.00 with 6 GB of memory and two logical volume utilized for swap.
I write below the output of lvlnboot command.

Boot Definitions for Volume Group /dev/vg00:
Physical Volumes belonging in Root Volume Group:
/dev/dsk/c1t6d0 (0/0/2/0.6.0) -- Boot Disk
/dev/dsk/c2t6d0 (0/0/2/1.6.0) -- Boot Disk
Boot: lvol1 on: /dev/dsk/c1t6d0
/dev/dsk/c2t6d0
Root: lvol3 on: /dev/dsk/c1t6d0
/dev/dsk/c2t6d0
Swap: lvol2 on: /dev/dsk/c1t6d0
/dev/dsk/c2t6d0
Dump: lvol2 on: /dev/dsk/c1t6d0, 0


Can you give me some advice about dump configuration?

Thanks

Filosofo

[Armin Feller · Accepted solution]

Hi,

if a system panics, it will dump the whole memory and the currently running kernel to the dump-device (lvol2 + secondary swap/dump if configured). After reboot the system will write the dump informations from the raw-device into the filesystem to /var/adm/crash (thats the default). You can configure the system dumping in /etc/rc.config.d/crashconf. For more details, refer to the HP-UX 11.0 System Crash Dump white paper, available online in /usr/share/doc/sys_crash.txt.

Hope that helps.

Regards ...
Armin

[Dietmar Konermann]

Hi, Filosofo!

Have a look at the Crash Dump Chapter 10 of the Software Recovery Handbook. It's usually a good starting point to understand the concepts.

http://www1.itrc.hp.com/service/iv/node.do?node=prod%2FWW_Start%2FN1%7C16
http://www4.itrc.hp.com/service/iv/node.do?node=prod%2FWW_Start%2FN1%7C16

Regards...
Dietmar.

[James Murtagh]

Hi Filosofo,

When the system panics the memory configured to be dumped is written to the swap areas from the end --> start (end means the end of the last configured dump area down to primary swap/dump on lvol2). This helps when the system boots and the swap area is utlised that hopefully the dump is not overwritten. When booting the system will then write this dump to a filesystem as specified in /etc/rc.config.d/savecrash.

To check what pages are included in the dump and how much will be dumped run:

# crashconf -v

The "pages included in dump" is the number of 4k pages to be included. This should be checked when all processes/applications are running and the filesystem area sized accordingly.

When analysing a dump we are not really interested in unused pages etc, hence at 11.00 we can now leave these out the dump to enable a faster boot/dump. One thing that should be changed from the default though - KCODE pages should be included. This can be configured in /etc/rc.config.d/crashconf. You can also turn this on immediately using crashconf.

Regards,

James.

[Filosofo]

Thanks for your importan answer.
What's happen if I execute lvlnboot -d /dev/vg00/lv_swap on my system?
It's dangerous?
I think to execute this comand because I have 6 GB of memory, and only one of dump(lvol2).
What do you think about this?
Thanks For ALL helps.

Filosofo

[Steve Steel]

Hi

see

http://www.docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B3782-90716/B3782-90716_top.html&con=/hpux/onlinedocs/B3782-90716/00/00/30-con.html&toc=/hpux/onlinedocs/B3782-90716/00/00/30-toc.html&searchterms=savecore%7cdumpfs&queryid=20030204-035026


This url explains well


Steve Steel

[James Murtagh]

Hi Filosofo,

No, its not dangerous! :-)

I'm being lazy here so will just paste what I did but it will show you the steps and what happens:

# lvlnboot -v
Boot Definitions for Volume Group /dev/vg00:
Physical Volumes belonging in Root Volume Group:
/dev/dsk/c0t6d0 (8/0/19/0.6.0) -- Boot Disk
Boot: lvol1 on: /dev/dsk/c0t6d0
Root: lvol3 on: /dev/dsk/c0t6d0
Swap: lvol2 on: /dev/dsk/c0t6d0
Dump: lvol2 on: /dev/dsk/c0t6d0, 0
# vxdisk list
DEVICE TYPE DISK GROUP STATUS
c0t6d0 simple - - LVM
c1t0d0 simple disk01 rootdg online
c1t2d0 simple disk02 oracledg online
c1t4d0 simple - - LVM
# pvcreate -f /dev/rdsk/c1t4d0
Physical volume "/dev/rdsk/c1t4d0" has been successfully created.
# vgextend vg00 /dev/dsk/c1t4d0
Volume group "vg00" has been successfully extended.
Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf
# lvcreate -l 100 -C y -r N vg00
Logical volume "/dev/vg00/lvol10" has been successfully created with
character device "/dev/vg00/rlvol10".
Logical volume "/dev/vg00/lvol10" has been successfully extended.
Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf
# lvlnboot -d /dev/vg00/lvol10
Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf
# lvlnboot -v
Boot Definitions for Volume Group /dev/vg00:
Physical Volumes belonging in Root Volume Group:
/dev/dsk/c0t6d0 (8/0/19/0.6.0) -- Boot Disk
/dev/dsk/c1t4d0 (8/16/5.4.0)
Boot: lvol1 on: /dev/dsk/c0t6d0
Root: lvol3 on: /dev/dsk/c0t6d0
Swap: lvol2 on: /dev/dsk/c0t6d0
Dump: lvol2 on: /dev/dsk/c0t6d0, 0
Dump: lvol10 on: /dev/dsk/c1t4d0, 1

So there you go, another dump dev. You can also do this another way by putting the entry in /etc/fstab as a dump device. Also, remember to increase the filesytem you have specified to write the dump to.

Regards,

James.

[T G Manikandan]

If you are going to configure a dump volume the volume should be contiguous in space

you can use
crashconf -v
to check the amount of space that will be needed for dump.

lvlnboot -d /dev/vg00/lv_swap

This command will make this volume as dump volume from the next reboot.
Make sure that the volume is contiguous.

THanks