Sessions limitation.

[Jeffrey F. Goldsmith]

We are having a login problem with our L2000 server. It has HP-UX 11.0 and we use the WQR software to connect to the server. It appears that the number of users allowed on at one time is being limited. Last week we were able to get 52 sessions to log-in. This morning we were able to get 57 sessions to log-in with out problems. Once the 58 session was started the user got an error and the telnet session failed.
Our license says that we have unlimited users so that cant be the problem. Does anyone know what could be the session limit? What do I need to do to correct the problem?

[Sanjay_6 · Accepted solution]

Hi,

Try

kmtune -S /stand/vmunix |grep nstrtel

This value is probably set to its default which i think is 60.

Increase this value and you should be able to have more telnet logins.

Try this link below,

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000072193096

The itrc doc id is KBRC00013957.

Hope this helps.

Regds

[Mel Burslan]

58 users for an L-Class, assumming all of them are connecting in for a reason and doing something, taking up some resources, is a tad bit high.

I would suggest checking your syslog and dmesg output to see if these is any complaint about it is out of some table space like file table is full or anything like that ? More than likely, you will need to bump up some kernel parameters.

[Navin Bhat_2]

Increase nproc, maxusers and also maxuprc for per user simultaneous procs.

[Navin Bhat_2]

Also increase npty

[Bill Hassell]

You don't have enough pty device files for all the connections. The default from HP is 60, usually fine for a small workstation but for an L-class, you can certainly have thousands, even tens of thousands of users logged in at the same time. There must be a set of device files for each connection. Change the three kernel parameters:

npty
nstrpty
nstrtel

Bump them all up to 200 and then adjust nproc and nfile. nproc should start at 2000 and nfile should be about 8000. When you use SAM to set these values, it will automatically create the required pty device files. Then monitor files and processes with sar -v 1 and adjust as necessary. Always have 20% unused so sudden growth will not require an immediate chaneg and reboot.

[Jeffrey F. Goldsmith]

Bill, here are the current settings:

npty = 200
nstrpty = 60
nstrtel = 60

nproc = 4096
nfile = 114548

I am waiting to see if i can boot my server at noon to make the changes to nstrpty & nstrtel as you suggested.

[Jeffrey F. Goldsmith]

Navin, here are the setting sizes that you recomended changing.

maxusers = 64
maxuprc = 528


Bill, here is the sar info:

root: /usr/sbin ==> sar -v 1

HP-UX diomede B.11.00 U 9000/800 05/17/04

11:52:18 text-sz ov proc-sz ov inod-sz ov file-sz ov
11:52:19 N/A N/A 332/4096 0 1729/8192 0 1270/114558 0

[Navin Bhat_2]

Bump up these tunables and you should be ok.

nstrpty nstrtel maxusers

[Robert-Jan Goossens]

Hi Jeff,

The guys above gave you all the info you need, use sam and change the kernel parameters you need. Start with maxusers, maxusers is used in the formula off other parameters

http://www.docs.hp.com/hpux/onlinedocs/939/KCParms/KCparam.MiscParamsOverview.html

Hope this helps,
Robert-Jan

[Bill Hassell]

Your nproc and nfile params are fine, barely used so there's lots of room for growth. npty is 200 but the streams-based pty values for pty and telnet are too small. Make all of them 200 or maybe 500 for some growth.

maxusers is a 'formula adjuster' so it isn't a real parameter. It makes a lot of assumptions which sometimes work OK, mostly not. And once you change a formula to a fixed value, changing maxuser no longer changes that value. I would move away from formula values and get to know the real value for your parameters, then monitor the corresponding resource (files, user connections, etc) and adjust as needed. Make sure adjustments are significant so you aren't constantly rebooting.