topic Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems? in Operating System - HP-UX

Cab be dump and swap on the same lvol? is it correct and not pottential problems?

MQ'ski — Wed, 14 Aug 2002 09:58:06 GMT

see swapinfo
Kb Kb Kb PCT START/ Kb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 790528 0 790528 0% 0 - 1 /dev/vg00/lvol2
dev 4096 0 4096 0% 0 - 1 /dev/vg00/lvol9
reserve - 794620 -794620
memory 1683580 687516 996064 41%

see fstab file
dev/vg00/lvol3 / hfs defaults 0 1
/dev/vg00/lvol1 /stand hfs defaults 0 1
/dev/vg00/lvol4 /home hfs defaults 0 2
/dev/vg00/lvol5 /opt hfs defaults 0 2
/dev/vg00/lvol6 /tmp hfs defaults 0 2
/dev/vg00/lvol7 /usr hfs defaults 0 2
/dev/vg00/lvol8 /var hfs defaults 0 2
/dev/vg00/lvol9 / dump defaults 0 0
/dev/vg01/lvol1 /var/opt/HP-AIN/cores hfs defaults 0 2
/dev/vg01/lvol2 /var/opt/HP-AIN hfs defaults 0 2
/dev/vg01/lvol3 /var/opt/HP-AIN/cpeun/checkpoint hfs defaults 0 2
/dev/vg02/lvol1 /var/opt/HP-AIN/cpeun hfs defaults 0 2
/dev/vg00/lvol9 ... swap pri=1 0 0

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

Pete Randall — Wed, 14 Aug 2002 10:00:50 GMT

No, it shouldn't be a problem.

Pete

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

MQ'ski — Wed, 14 Aug 2002 10:02:24 GMT

Thanks...
I will aplicate it

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

Pete Randall — Wed, 14 Aug 2002 10:17:17 GMT

Marcin,

Actually, opinions vary on this subject. I think it's OK but see Bill McNamara's response in this thread:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x48d8f715edc6d5118ff10090279cd0f9,00.html

Pete

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

Ceesjan van Hattum — Wed, 14 Aug 2002 10:28:40 GMT

Default swap and dump on lvol2. No problem!
Only on mirrored disks, the dump is cannot and will not be mirrored.
See 'lvlnboot -v'.

Regards,
Ceesjan

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

Bill Hassell — Wed, 14 Aug 2002 10:29:12 GMT

Swap and dump are mutually exclusive. If you are swapping then HP-UX is running. If your machine crashes then the swap area is meaningless and the OS writes the crash dump to this dual purpose area.

Now there is an advantage to having a separate dump area. If you have plenty of disk space, you can allocate about 25% of the size of your RAM to dedicated dump area(s). Then, if the machine crashes, when it comes back up, you can have the savecrash configuration set to LOG_ONLY=1 and SAVECRASH=0. This will speed up the reboot process significantly after a crash (saving a 24Gb crash dump takes a *LONG* time).

Since swap is on separate volumes, you can manualy run savecrash at a later time once things are back to normal. You can also run savecrash out to a tape rather than to /var/adm/crash. The tape image is a series of files in tar format.

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

MQ'ski — Wed, 14 Aug 2002 10:41:45 GMT

Ok. But I understand that it is possible to have mentioned my configuration
.....
/dev/vg00/lvol9 / dump defaults 0 0
....
dev/vg00/lvol9 ... swap pri=1 0 0

I have not too much choise.
I cannot tune kernel parameters because (I suppose it need reboot).
I can only choise free lvol.

As I understand. If system works it lvol9 will be used as swap area...
If sth happen swap area is not needen anymore and lvol9 will be used as dump.
Am I right.
So can I use this configuration?

Re: Cab be dump and swap on the same lvol? is it correct and not pottential problems?

MQ'ski — Wed, 14 Aug 2002 10:44:05 GMT

beside... after that I will have
swap on
/dev/vg00/lvol2 and /dev/vg00/lvol9
and
dump on /dev/vg00/lvol9