[hobbit] Important ! HP-UX and the memory utilisation

[lars ebeling]

From: <thomas.seglard.enata at cnp.fr>
To: <hobbit at hswn.dk>
Sent: Tuesday, July 25, 2006 2:34 PM
Subject: [hobbit] Important ! HP-UX and the memory utilisation


> Hello,
>
> I got some troubles with HPUX and memory values. With Hobbit, in my memory
> test, I got this :
>
> Memory              Used       Total  Percentage
> Physical          16156M      16372M         98%
> Swap              22117M      40372M         54%
>
> Everything seems normal but for me, these numbers are high 'cause this
> server does nothing during the day. So, I connected to the server and ran
> this command to see the available memory :
>
> psd216:~# swapinfo -atm
>             Mb      Mb      Mb   PCT  START/      Mb
> TYPE      AVAIL    USED    FREE  USED   LIMIT RESERVE  PRI  NAME
> dev       24000    5474   18526   23%       0       -    1 /dev/vg00/lvol2
> reserve       -   11550  -11550
> memory    16372    4754   11618   29%
> total     40372   21778   18594   54%       -       0    -
>
> This output clearly shows an error in the Hobbit display. If you look, my
> total swap memory is equal to 24000M not 40372M as shown in Hobbit and
> only 23% is used !! Apparently, the values for the swap memory test are
> taken from the last line and that's not correct !
> Then I tried to execute the binary called "hpux-meminfo" in the client
> "bin" directory and I get this :
>

The 24000M is not swapmemory it is swapdisk, ie diskdevice configured to be 
used for swap.

The 16372 is swapmemory or pseudo-swap as HP name it. It is a part of memory 
that could be used used for swapping (or as I prefer paging). If you have a 
lot of memory it is more efficient to use memory for paging. When a process 
is started in HP-UX swapdisk is reserved for the process (reserve above). If 
that swap isn't used, it's is waste of diskresources.

It is a try to explain.

Regards
Lars Ebeling