memory question

[Chris Nelson 72]

I'm looking for help to get a better understanding of memory on our HP-UX 9000 series server running 11i v1. PA-RISC, 4 proc, 6Gb. Running 1 instance of IDS 9.4 with roughly 140 users.

The output of "# dmesg | grep Physical" shows we have 6 GB of physical RAM installed:
Physical: 6291456 Kbytes, lockable: 4735068 Kbytes, available: 5453328 Kbytes

Therefore at bootup, I'm assuming 0.8Gb for the kernel:
"Physical memory"="Available memory"+"/stand/vmunix"
6Gb=5.2Gb+0.8Gb

When I run vmstat I'm expecting to see all 5.2Gb of avail RAM, however in the memory section it only shows:

avm=731129
free=114167

I believe these are in pages. "# dmesg | grep physical" shows our HP-UX has 4kb/page, so thats roughly 2.79 GB active vm, 446 Mb free, correct?

Why isnt vmstat showing all the "available memory"? Is the kernel just using 0.8Gb at startup and growing to roughly 3Gb?

Also, I thought HP defined VM as: all available memory + swap space? Then I would expect to see the 5.2GB available memory + 4096Mb dev swap + 4633Mb memory swap (pseudo) in vmstat. Is this incorrect thinking?

We dont have glance. I have yet to play with sar. Mainly using top, vmstat and swapinfo at this time.

I'm trying to digest the memory management white paper, the system&network admin I book we have as well as posts on this forum that I have read and connect the dots.

Thanks

[Dennis Handly]

It would be interesting to see your "swapinfo -tam" output.

Is there a specific problem you are trying to solve? Are you doing capacity planning?

[Javed Khan_1]

Hi,

You can try with glance evaluation version.

Also here is the doc for HP-UX memory Management

http://docs.hp.com/en/1218/mem_mgt.html


Javed

[Jaime Bolanos Rojas.]

Chris,

This document should help you on your quest to understand memory management better:

ftp://eh:spear9@hprc.external.hp.com/memory.htm

Regards,

Jaime.

[Chris Nelson 72]

Here is my vmstat and swapinfo -tam output.

# vmstat
procs
r b w
1 1 0

memory
avm free
651369 7458

page
re at pi po fr de sr
113 37 0 0 0 0 6

faults
in sy cs
1280 12540 715

cpu
us sy id
6 2 92


# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 4096 783 3313 19% 0 - 1 /dev/vx/dsk/rootdg/swapvol
reserve - 1958 -1958
memory 4633 3323 1310 72%
total 8729 6064 2665 69% - 0 -

[Chris Nelson 72]

Dennis-

Yeah, mainly looking at this from a capacity planning point of view. We will most likely be upgrading the server hardware in the next 6 - 12 months and I wanted a good understanding of where we are at resource wise now. Having 6 physical gigs and only seeing 3 in vmstat is confusing.

Jaime-

Thanks for the link, I will give that a read soon as time allows.

Jared-

Thanks for the tip on the eval version. I would like to become proficient with native utilities first though. I did read the white paper you linked already. I was able to absorb what I was ready for at this time. My questions will hopefully help me get a better understanding of the topic.

thanks all,
Chris

[Chris Nelson 72]

Can anyone help further explain the output of the vmstat and swapinfo utils?

vmstat output:
active 651,369 pages (2.48 GB)
free 7,458 pages (29.1 MB)

Given the vmstat numbers, to get the total amount of Virtual Memory, do you add active+free=total vm?
2.48GB+29.1MB=2.51GB


I have 5.2GB "active memory" (6.0GB physical)
I have 4GB of device swap.
I have 4.52GB of pseudo swap.

Given those numbers, shouldnt total VM be:
VM="active memory"+"all swap"? (13.72GB)


The 2.51GB total VM vmstat reports on isnt close to the 13.72GB total VM I *think* I should have. So what am I missing?

[Dennis Handly]

>to get the total amount of Virtual Memory,

You simply look at the total line for "swapinfo -tam".

>Given those numbers, shouldn't total VM be:
>VM="active memory"+"all swap"? (13.72GB)

You are adding some up twice. "active memory" is RAM, swap is swap.