Hello,
with your help I'm beginning to understand !! It's very difficult to determine the true memory usage on hpux...
I'm confusing with the fact that every process on hpux will reserve a maximum space of memory on "swapdisk". So, it's normal on hpux to have a high percentage of swap space used even when server have a very little amount of applications running. But, it's a problem when disk is swapping continuously (you can see that with the "pi" and "po" metrics on vmstat output, right ?).
The other point is the weird behaviour of the system memory ( = main memory = physical memory = RAM ?). This memory is used as a part of the swap space if you activate an operating-system parameter : swapmem_on (by defautl is set to 1). At this time, the part of the system memory embedded in the swap space is called "pseudo-swap". In the HP documentation, I read that only three-quarters of the system memory could be used into swap space. Thus, I don't understand why I'm getting 16372M available on the "memory" line from my "swapinfo" output ?! From what HP says I would only have 12G available for the pseudo-swap ! My system has 16Go of physical memory or RAM.
As I wrote before, the main problem is the amount of "reserved" memory because it's a max value ! So, the values indicated by "swapinfo" are bigger than the actual memory used by the system. Look at this new output :
psd216:~# swapinfo -tm Mb Mb Mb PCT START/ Mb TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME dev 24000 973 23027 4% 0 - 1 /dev/vg00/lvol2 reserve - 9876 -9876 memory 16372 4764 11608 29% total 40372 15613 24759 39% - 0 -
In fact, only 5737M (4764+973) of swap space is actually used. That corresponds to 14% of the total swap space. In case of troubles or necessity, processes COULD require a maximum value of 9876M taken from the reserved memory. In this case, you will have a swap space full at 39%... Am I right on this point ?
I'm so sorry to make such troubles for nothing but I want to understand how memory management works on hpux !! Thanks again for all your patience and help ! Best regards,
Thomas
Here is some very useful documentation :
http://www.docs.hp.com/en/5965-4641/ch01s09.html#d0e4274
http://unix.ittoolbox.com/groups/technical-functional/hp-ux-l/swap-511113#
http://www.math.ntnu.no/~perhov/public/unix/memory.html
"lars ebeling" <lars.ebeling at leopg9.no-ip.org> a écrit sur 28/07/2006 07:16:42 :
Hi,
From hpux-meminfo you get the 95% = (Total-Free)/Total . When you start > HP-UX memory is used for "swapping" (up to 75%) and that is included in > (Total-Free). This is called pseudo-swap. This is controlled by the kernelparameter swapmem_on. By default it's on (=1).
Memory used by processes should be 16372 - 212 - 4770
29% of your memory is used for pseudo-swap. 30% of your swapdisk is used.
Everytime when a process is started space on you swapdisk is reserved, so that the process won't run out of swapspace when it's needed.
Total Available swap = Available memory + Available swapdevice Total Used swap = Used memoryswap + Used deviceswap + Reserved deviceswap
More confused now???
Regards Lars Ebeling
----- Original Message ----- From: <thomas.seglard.enata at cnp.fr> To: <hobbit at hswn.dk> Sent: Thursday, July 27, 2006 2:46 PM Subject: Re: [hobbit] Important ! HP-UX and the memory utilisation
Hello,
Thanks for your explanation ! I'm sorry to insist but it's a bit hard to understand. I think the true problem is the "reserved" memory. It's a maximum value and may not be used totally. For me, the real information is on the first line and given by the swapdisk. In my example, I got a total of 24G for swapping (also called paging by HP) and only 23% is used. Moreover, to determine the total physical memory used, a little script called "hpux_memory" is launched. I got very different results between this script and "swapinfo -Mm" :
bash-3.00$ ./hpux-meminfo Total:16372 Free:212
So, on my hobbit display I got percentage of memory utilisation > 95% whereas I got 29% with the other command !! Where is the truth ?!
bash-3.00$ /usr/sbin/swapinfo -Mm Mb Mb Mb PCT TYPE AVAIL USED FREE USED memory 16372 4770 11602 29%
For the swap or paging memory, "swapinfo -dm" :
bash-3.00$ /usr/sbin/swapinfo -dm Mb Mb Mb PCT Mb TYPE AVAIL USED FREE USED START RESERVE PRI NAME dev 24000 7264 16736 30% 0 - 1 /dev/vg00/lvol2
I got several servers with two or more swapdisks, so this command may be launched :
psu106:/# /usr/sbin/swapinfo -dtm Mb Mb Mb PCT Mb TYPE AVAIL USED FREE USED START RESERVE PRI NAME dev 8192 4906 3286 60% 0 - 1 /dev/vg00/lvol2 dev 8192 4908 3284 60% 0 - 1 /dev/vg00/lvol3 dev 6144 5735 409 93% 0 - 0 /dev/vg_swap/lv_swap01 total 22528 15549 6979 69% - 0 -
If you can explain me where I'm wrong I would greatly appreciate ! Thanks again ! Sincerly,
Thomas
"lars ebeling" <lars.ebeling at leopg9.no-ip.org> a écrit sur 25/07/2006 18:05:31 :
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
To unsubscribe from the hobbit list, send an e-mail to hobbit-unsubscribe at hswn.dk
Ce message (et toutes ses pieces jointes eventuelles) est confidentiel et etabli a l'intention exclusive de ses destinataires. Toute utilisation de ce message non conforme a sa destination, toute diffusion ou toute publication, totale ou partielle, est interdite, sauf autorisation expresse. L'internet ne permettant pas d'assurer l'integrite de ce message, CNP Assurances et ses filiales declinent toute responsabilite au titre de ce message, s'il a ete altere, deforme ou falsifie.
This message and any attachments (the "message") are confidential and intended solely for the addressees. Any unauthorised use or dissemination is prohibited. E-mails are susceptible to alteration. Neither CNP Assurances nor any of its subsidiaries or affiliates shall be liable for the message if altered, changed or falsified.
To unsubscribe from the hobbit list, send an e-mail to hobbit-unsubscribe at hswn.dk
To unsubscribe from the hobbit list, send an e-mail to hobbit-unsubscribe at hswn.dk
Ce message (et toutes ses pieces jointes eventuelles) est confidentiel et etabli a l'intention exclusive de ses destinataires. Toute utilisation de ce message non conforme a sa destination, toute diffusion ou toute publication, totale ou partielle, est interdite, sauf autorisation expresse. L'internet ne permettant pas d'assurer l'integrite de ce message, CNP Assurances et ses filiales declinent toute responsabilite au titre de ce message, s'il a ete altere, deforme ou falsifie.
This message and any attachments (the "message") are confidential and intended solely for the addressees. Any unauthorised use or dissemination is prohibited. E-mails are susceptible to alteration. Neither CNP Assurances nor any of its subsidiaries or affiliates shall be liable for the message if altered, changed or falsified.