npty limits nstrpty?

[Dan Weiner_1]

Is npty an effective upper bound on nstrpty? That is, if npty=100 and nstrpty=400, is nstrpty effectively limited to 100?

Thanks!

[Pete Randall · Accepted solution]

Dan,

Here's what SAM says about nstrpty:

"This parameter should be set to a value that is equal to or greater than the number of PTY devices on the system that will be using streams-based I/O pipes. Using a parameter value significantly larger than the number of PTYs is not recommended. nstrpty is used when creating data structures in the kernel to support those streams-based PTYs, and an excessively large value wastes kernel memory space."

So, the answer to your question would be no.


Pete

[Dan Weiner_1]

Thanks, Pete.

My next question is, what determines whether I am assigned a pty or a STREAM pty? Is it different for telnet and SSH connections? Thanks again!

[Armin Kunaschik]

Telnet connections use their "own" kernel parameter nstrtel.
If you increase the kernel parameters remember to create the apropriate device files like
insf -d ptym -n 100
insf -d ptys -n 100
insf -d pts -s 400
and for telnet devices
insf -d tels -s 512

My 2 cents,
Armin

[Bill Hassell]

No, NPTY limits the maximum number of classic PTY connections, while NSTRPTY limits the number of streams-based PTY connections (and NSTRTEL limits telnet streams). HP-UX has been migrating various network stacks from classic to streams-based code over several years, so depending on which version(s) and patch levels of HP-UX you are using (9.00...11.31), the service may use classic PTYs or streams-based. Since I have found no official list of services versus PTY class, make all THREE the same value:

NPTY = NSTRTEL = NSTRPTY = 500

These parameters just reserve space for connection tables. Making all 3 a lot larger than you currently need is a good idea -- they occupy very little space.

As mentioned, you must set the kernel parameters, but then run insf to create the device files. The device files must match the kernel parameters. If you use SAM, this is all automatic.