Dump area configuration

[Roberto Volsa]

Hello,
my dump area is too small to contain a full memory dump.
I can find space only into an external disk.
Can i configure a lvol on this external disk as dump area? Is it supported?
Have i to delete vg00/lvol2 as dump area?
Thanks a lot

[Donald Kok]

dumparea can be on another disk, but must be hfs and not vxfs. there can only be one dump area, but you should not 'delete' /vg00/lvol2 as it still is swapspace.

[Roberto Volsa]

Thanks for your reply.
i don't want to delete lvol2, i want to know if i must set only external lvol as dump area and thus set vg00/lvol2 not as dump area.

[Paula J Frazer-Campbell]

Hi

You can change the crash area in :-

/etc/rc.congig.d/savecrash


i.e.

SAVECRASH_DIR=/crash/crash


HTH

Paula

[Paula J Frazer-Campbell]

Hi

that should be


/etc/rc.config.d/savecrash


Paula

[Roberto Volsa]

Hello Paula,
are you saying that changing the value of SAVECRASH_DIR=/crash/crash in /etc/rc.congig.d/savecrash is the same as:
- lvlnboot -r -d /dev/vg00/lvol2
- lvlnboot -d /dev/vg01/lvol1
I recall you that vg01/lvol1 is setted on an externale disk and i don't know if this volume group is activated at boot time before saving crahs dumps.
Thanks

Roberto

[Frank Slootweg]

An extra dump area can be configured on an extra disk, but that disk must be in the root Volume Group (vg00). See the lvlnboot(1M) manual page on the requirements for and limitations of dump (and swap and root and boot) logical volumes.

[MANOJ SRIVASTAVA · Accepted solution]

Hi Roberto


Here is something for the docs :

How Much Dump Space Do I Need?

For selective dumps, use crashconf(1M) to find out how much space would be needed for a selective dump of your machine. (Use the -v flag, and run it while your system is under its normal or higher than normal workload.) The space needed will vary depending on the workload of the machine, so add another 25% or so to be safe. The total dump space should meet or exceed this amount.

For machines that are relatively stable and don't expect to dump often, this is enough. If a full dump is needed from such a machine, additional space can be configured for it on the fly, anyway. This space can also be used for swap unless reboot times are critical.

For machines on which full dumps are required, the full size of physical memory, plus a little bit for dump headers and tables, should be configured as dump space. At least the amount needed for a selective dump should be configured on a device that is not used for swap activity.

For example, the size of a selective dump for a 1GB RAM system typically ranges from 100MB to 200MB (10% to 20%). Extrapolating this to a 64GB system, a dump could be as large as 12GB.

Whenever you have dump devices that are not also used for swap activity, make sure that they are configured last. This will cause them to be used first (dump goes from the end backward), which will minimize the chance of writing into an area shared by swap. Writing into swap space is undesirable because it will slow down your reboot processing; see Post-Reboot Dump Processing, for details.


You amy like to look at this page too :


http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/sysdmp-62001/sysdmp-62001_top.html&con=/hpux/onlinedocs/sysdmp-62001/00/00/6-con.html&toc=/hpux/onlinedocs/sysdmp-62001/00/00/6-toc.html&searchterms=partition%7cdump&queryid=20020716-073748


Manoj Srivastava