topic Re: Re-use template device numbers (e.g. RTA1) in Operating System - OpenVMS

Re-use template device numbers (e.g. RTA1)

Steve Reece_3 — Fri, 16 Jul 2010 15:11:20 GMT

Hiya,

I seem to recall in my dim and distant past that there was a SYSGEN parameter which determined whether a template device should allocate a new number to a device like RTA or whether it would reuse device numbers.

so, if I connected via SET HOST FRED, logged out, then did SET HOST FRED again, the same RTA device number wasn't reused - the system allocated RTA1: the first time, RTA2: the second, then carried on allocating new device numbers until the wrap around of 9999 was reached and then restarted at 1.

Was I dreaming this? If not, what SYSGEN parameter controlled it please?

Thanks in advance.

Steve

Re: Re-use template device numbers (e.g. RTA1)

RBrown_1 — Fri, 16 Jul 2010 16:05:37 GMT

>>>>
so, if I connected via SET HOST FRED, logged out, then did SET HOST FRED again, the same RTA device number wasn't reused - the system allocated RTA1: the first time, RTA2: the second, then carried on allocating new device numbers until the wrap around of 9999 was reached and then restarted at 1.
<<<<

That is the behaviour I remembered and expected, without having to do any special settings.

I am on VMS 7.1 on alpha.

This is what I found when I actually tried it:

o with RT, it reused the unit number --- I logged into RTA1 twice in a row.

o with TN (telnet), it incremented the unit number each time --- logged in to TNA44, disconnected and logged in again, this time I was on TNA45.

o with LT, it double-incremented the unit number --- first I logged in to LTA5009, next to LTA5011, and then to LTA5013!

Once again, it seems, "it depends".

Re: Re-use template device numbers (e.g. RTA1)

Phil.Howell — Sun, 18 Jul 2010 01:54:34 GMT

It could be the DEVICE_NAMING parameter, but documentation on its values seems hard to find.
Phil

Also see
http://forums13.itrc.hp.com/service/forums/questionanswer.do?&threadId=1074590

Re: Re-use template device numbers (e.g. RTA1)

Jur van der Burg — Sun, 18 Jul 2010 07:06:30 GMT

There's no such parameter. Decnet is not using a template device (it's handled differently) so you will see a re-use of unit numbers.

Other devices like LAT and TELNET use a template device (there's a unit 0). It is used by assigning a channel to LTA0 for example, and in return a new device is created from that unit with a new unitnumber which is taken from a seed value in the template device's ucb. Normally you will get an increasing unit number, but drivers can play tricks to get the desired unit (LDdriver uses that trick).

Jur.

Re: Re-use template device numbers (e.g. RTA1)

Steve Reece_3 — Sun, 18 Jul 2010 10:13:28 GMT

Thanks Jur. That's what I feared but hoped wasn't the case.

Re: Re-use template device numbers (e.g. RTA1)

Steve Reece_3 — Sun, 18 Jul 2010 10:14:19 GMT

Jur provided the answer on this so closing the thread.
Thanks Jur.