30 May
2020
30 May
'20
7:14 p.m.
Good afternoon everyone,
What are you guys doing to get something like OPC$CRASH invoked when a UPS signals it is
on battery?
I have serial connectivity to TTAx ports on a Microvax 3100-80 running OVMS 7.3.
Recommendations on a UPS?
Generally how do you get a VAX to shut down immediately on UPS going on battery?
Thanks in advance
Supratim
---
Supratim Sanyal, W1XMT
39.19151 N, 77.23432 W
QCOCAL::SANYAL via HECnet
31 May
31 May
8:30 p.m.
Can anybody elaborate more on what the VMS power failure options are??
OPC$CRASH sure looks like a crash, but what happens before the belly up?
Some time ago (at least a decade), I started looking at re-enabling the
Tops-20's power failure code with an eye towards making some changes to
the KLH10 micro-engine.? So clearly, at a minimum, I would have needed
to catch a SIGPWR and then do something useful with it, which then meant
some nosing around in APRSRV and SCHED and some other monitor code.
At one point, Tops-20 appears to actually have been able to save what it
was doing and cleanly resume on power up; in other words, not crash.?
Some hardware was able to detect a power fail and cause an APR generated
PI.? Any running process was dismissed, the front end was notified and
any disk I/O was completed.? The caches were shut off.? That leaves the
volatile structures.? Assuming you were running with core (MA20's), you
could survive the power outage.? A power on would generate an interrupt
which checked whether the power off handling was completed.? If so, away
you went.
I don't ever remember ever that working at Columbia, which stands to
reason since we were running semi-conductor memory. We only had a single
MA20 to increase the total memory of one particular system to 3.75 MW
(the rest was MF20).
However, the code itself is still there.? Fully supporting the power
fail would have then involved the 20 signaling the micro-engine (perhaps
by doing a CONO to the Idler device with a magic bit set), that it was
done.? KLH10 would then have had save about 34 MB of memory and exit.
It wasn't clear what volatile structures in the micro-engine needed to
be preserved, so I stopped there and turned to other things.? If the
host operating supported sleep, maybe not much. You can't just 'sleep'
Tops-20 because on resumption, the keep-alive counters won't have been
updated and it will immediately crash.?? It has to know the power went out.
If you don't have a UPS, you may not have a lot of time to do things.?
Depending on the power supply and capacitor usage and discharge, you
might have only milliseconds.? I would imagine that's plenty for SSD
storage, it might not be enough for rotating media.
------------------------------------------------------------------------
On 5/30/20 1:14 PM, Supratim Sanyal wrote:
Good afternoon everyone,
What are you guys doing to get something like OPC$CRASH invoked when a
UPS signals it is on battery?
I have serial connectivity to TTAx ports on a Microvax 3100-80 running
OVMS 7.3. Recommendations on a UPS?
Generally how do you get a VAX to shut down immediately on UPS going
on battery?
Thanks in advance
Supratim
---
Supratim Sanyal, W1XMT
39.19151 N, 77.23432 W
QCOCAL::SANYAL via HECnet <http://www.update.uu.se/~bqt/hecnet.html>
9:02 p.m.
On Sun, 31 May 2020 14:30:15 -0400, Thomas DeBellis wrote:
Can anybody elaborate more on what the VMS power
failure options are??
OPC$CRASH sure looks like a crash, but what happens before the belly up?
You may want to take a look at the VAX/VMS Internals and Data Structures
manuals on Bitsavers where you could find editions for V3.3, V4.4, and V5.2.
There is a whole part (VII or VIII depending on the edition) completely
devoted to the bootstrap process, initialization, shutdown, power failure
and recovery, and so on :)
See http://bitsavers.org/pdf/dec/vax/vms/training/
Quote from the V5.2 book: ?Powerfail recovery support enables a suitably
equipped VMS system to survive power fluctuations and power outages of short
duration with no loss of operation. The support is provided by hardware
features (battery backup) and VMS software routines. VMS support includes a
powerfail service routine that saves the volatile state of the machine when
the power fails, a restart routine that restores that state when the power
is restored, CPU-specific initialization code, and device-specific code
within many VMS device drivers. The VMS software also provides process
notification by means of power recovery asynchronous system traps (ASTs)?.
HTH, :)
G.
1 Jun
1 Jun
12:46 a.m.
On 2020-05-31 21:02, G. wrote:
On Sun, 31 May 2020 14:30:15 -0400, Thomas DeBellis
wrote:
Very similar story as with RSX. However, I wonder if that was kept
maintained in VMS.
It requires that all memory are either core (which don't exist for
VAXen), or battery backed. Battery backed memory certainly did exist,
but I suspect that eventually went out of fashion.
Same on RSX. Either core, or battery backed main memory. The CPU
volatile state is saved at power loss, and execution resumes when power
is restored. Device drivers and programs can get notified about a power
loss and resumption.
Dumping all of memory to permanent storage was never an option, as the
power loss means you only had something in the order of 20ms of
execution time left.
UPSes work on a very different principle. They are meant to be able to
keep the system running for a while when power is lost. And then you can
do a graceful shutdown if needed.
Not sure if VMS have any hooks in place to force a graceful shutdown.
RSX do not, that I can remember.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Can anybody elaborate more on what the VMS power
failure options are?
OPC$CRASH sure looks like a crash, but what happens before the belly up?
You may want to take a look at the VAX/VMS Internals and Data Structures
manuals on Bitsavers where you could find editions for V3.3, V4.4, and V5.2.
There is a whole part (VII or VIII depending on the edition) completely
devoted to the bootstrap process, initialization, shutdown, power failure
and recovery, and so on :)
See http://bitsavers.org/pdf/dec/vax/vms/training/
Quote from the V5.2 book: ?Powerfail recovery support enables a suitably
equipped VMS system to survive power fluctuations and power outages of short
duration with no loss of operation. The support is provided by hardware
features (battery backup) and VMS software routines. VMS support includes a
powerfail service routine that saves the volatile state of the machine when
the power fails, a restart routine that restores that state when the power
is restored, CPU-specific initialization code, and device-specific code
within many VMS device drivers. The VMS software also provides process
notification by means of power recovery asynchronous system traps (ASTs)?. 
1:22 a.m.
APC offered software to detect power failure using their UPSes for VMS but it was for the
units that predate machines with USB support. Connection was via serial port.
-Steve Davidson
SF:iP1
On May 31, 2020, at 18:46, Johnny Billquist <bqt at
softjar.se> wrote:
?On 2020-05-31 21:02, G. wrote:
Very similar story as with RSX. However, I wonder if that was kept maintained in VMS.
It requires that all memory are either core (which don't exist for VAXen), or battery
backed. Battery backed memory certainly did exist, but I suspect that eventually went out
of fashion.
Same on RSX. Either core, or battery backed main memory. The CPU volatile state is saved
at power loss, and execution resumes when power is restored. Device drivers and programs
can get notified about a power loss and resumption.
Dumping all of memory to permanent storage was never an option, as the power loss means
you only had something in the order of 20ms of execution time left.
UPSes work on a very different principle. They are meant to be able to keep the system
running for a while when power is lost. And then you can do a graceful shutdown if
needed.
Not sure if VMS have any hooks in place to force a graceful shutdown. RSX do not, that I
can remember.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
On Sun,
31 May 2020 14:30:15 -0400, Thomas DeBellis wrote:
Can anybody elaborate more on what the VMS power failure options are?
OPC$CRASH sure looks like a crash, but what happens before the belly up?
You may
want to take a look at the VAX/VMS Internals and Data Structures
manuals on Bitsavers where you could find editions for V3.3, V4.4, and V5.2.
There is a whole part (VII or VIII depending on the edition) completely
devoted to the bootstrap process, initialization, shutdown, power failure
and recovery, and so on :)
See http://bitsavers.org/pdf/dec/vax/vms/training/
Quote from the V5.2 book: ?Powerfail recovery support enables a suitably
equipped VMS system to survive power fluctuations and power outages of short
duration with no loss of operation. The support is provided by hardware
features (battery backup) and VMS software routines. VMS support includes a
powerfail service routine that saves the volatile state of the machine when
the power fails, a restart routine that restores that state when the power
is restored, CPU-specific initialization code, and device-specific code
within many VMS device drivers. The VMS software also provides process
notification by means of power recovery asynchronous system traps (ASTs)?. 
1:41 a.m.
There was a thing called "REMOTE-SHUTDOWN-LISTENER" which would wait for a
connect to a particular TCP port and then run OPC$CRASH when that happened. It was
intended for use with simh to allow the guest VMS OS to be shut down automatically when
the host OS shuts down. Not exactly what is wanted, but it shouldn't be too hard to
adapt to listen to a serial port instead.
Don't remember who wrote it, but the C source is included. I put a copy in
LEGATO::REMOTE-SHUTDOWN-LISTENER.ZIP.
Bob
31 May
31 May
9:25 p.m.
On Sat, 30 May 2020 13:14:12 -0400, Supratim Sanyal wrote:
What are you guys doing to get something like
OPC$CRASH invoked when a UPS
signals it is on battery?
I have serial connectivity to TTAx ports on a Microvax 3100-80 running OVMS
7.3. Recommendations on a UPS?
Generally how do you get a VAX to shut down immediately on UPS going on
battery?
What about a batch DCL procedure waiting for something to appear on the
serial port? If you do not want to rely on batch processing you could do the
same with a detached process running either LOGINOUT.EXE and the same DCL
procedure or some home-made HLL program performing the same actions. If you
are really tight on battery time you could just set up the relevant OPC$*
logicals and call OPC$CRASH.EXE otherwise you could just run SHUTDOWN.COM
and let it do everything it's needed.
I have some faint recollection of something ready-made but I do not remember
anymore if it was in some SPL or in the Freeware.
HTH, :)
G.
1438
days inactive
1439
days old
6 comments
6 participants
participants (6)
-
bob＠jfcl.com -
bqt＠softjar.se -
gerry77＠mail.com -
steve＠davidson.net -
supratim＠riseup.net -
tommytimesharing＠gmail.com