topic Re: swap......need advice!!!!! in Operating System - HP-UX

swap......need advice!!!!!

Steve_3 — Thu, 18 Jan 2001 22:34:24 GMT

output of swapinfo -tm

Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 1024 156 868 15% 0 - 1 /dev/vg00/lvol2
reserve - 868 -868
memory 2993 2700 293 90%
total 4017 3724 293 93% - 0 -

my current swap area is 1 Gig on lvol2
how does the system set how much is reserve? 868?

my resource is pretty low..should i add another swap area of 1 Gig?
is there are kernel that need to be change is added?

help,
steve

Re: swap......need advice!!!!!

James R. Ferguson — Thu, 18 Jan 2001 23:20:40 GMT

Hi Steve:

This thread should provide your answers!

http://my1.itrc.hp.com/cm/QuestionAnswer/1,1150,0x53a08b55dfd6d4118fef0090279cd0f9!1,00.html

...JRF...

Re: swap......need advice!!!!!

Steve_3 — Thu, 18 Jan 2001 23:31:53 GMT

If I configure the swap through SAM, is there a reboot??

Thanks,
steve

Re: swap......need advice!!!!!

James R. Ferguson — Thu, 18 Jan 2001 23:54:56 GMT

Hi Steve:

If you ADD swap there is no reboot necessary. If you want to delete swap, then you must reboot.

The "HP-UX System Administration Tasks" manual has a very good chapter on managing swap:

http://docs.hp.com/hpux/onlinedocs/B2355-90672/B2355-90672.html

...JRF...
...JRF...

Re: swap......need advice!!!!!

Shannon Petry — Fri, 19 Jan 2001 03:56:59 GMT

James, your not correct. There are two reasons you may have to reboot.
1. If there are not enough swapchuncks available, then you have to build the kernel and boot the new kernel into place. If adding swap in sam, you will be told whether or knot you have enough swap chuncks for the current config. Sam will do a pretty good job of telling you how to estimate swap chunks. Press F1 for help at the pop-up where you would modify the kernel parameter.
2. If you change swap priority on the booted swap, you will have to reboot to change the priority.
NOTE: If two swap areas are set to priority 0 for both then it is treated as 0 for first area, 1 for second. To have syncronous writing, both swap chunks must need to be priority 1 or higher. Default is to make swap2 priority 1, which means your first area will be used alone until full, then it would use your next swap.
If you have 4 swap chunks, and wanted syncronous writes in two segments
swap1 PRI 1
swap2 PRI 1
swap3 PRI 2
swap4 PRI 2
This would use syncronous writing to swap1 and swap2 until full, at which point it would use syncronous writes to swap3 and swap4.
Pretty cool eh!

Best regards,
Shannon

Most people who have done this for a while add extra at first build, but then again......

Regards,
Shannon