Solaris 9 error - "Unable to allocate a master pty."

When adding or reseting serial printers in on Solaris 9 system, we use the following command (as an example):

/usr/opt/annex/rtelnet -broaP 7002 /dev/bm015

This seems to work fine most of the time, but occasionally an error such as the following will appear:

ERR :10512:20041027204139: Unable to allocate a master pty.

When this error occurs, the only way around it is to do a reboot; which is not very convenient.  Please let us know what is causing this error and provide a way around it outside of having to reboot the system.

Shannon Adams
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Brian UtterbackPrinciple Software EngineerCommented:
Verify that the daemons syseventd and devfsadmd are running. Check /var/adm/messages for any messages from either of them.
If they are running, run "ls -l /dev/pts" and verify that there are only the devices in there that are files with only digits as names.
You system might reach the max number of rtelnet sessions limit. (for olderr Solaris is 60, for new one is 45)!

You can try to modify /etc/system to set pt_cnt and nautopush to see if it can help (need a reconfigure boot).

The following example increases the number of ptys to 128:
set pt_cnt=128
set npty=128
set sadcnt=256
set nautopush=128

see the following doc to learn more:

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Brian UtterbackPrinciple Software EngineerCommented:
Unfortunately (or fortunately depending on how you look at it) the document that yuzh gave is for Solaris 2.6. Starting
in Solaris 8 the system used to allocate ptys was made dynamic. In general the number of ptys allocated
is only limited by the amount of memory you have available. You should not have to tune anything unless there is
something going wrong with the daemons that control it.
You can try to apply the Solaris 9 latest patchs to the system to see if it can help.

or modify /etc/system as I mentioned in my aerly comment to force it to

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