[HECnet] SETNOD, Part 2

Tue Jun 1 08:48:36 PDT 2021

You are correct; the Tops-20 Executor will allow you to do precisely two 
(2) things after initialization:

 1. Set the Executor to the exact same name
 2. Set the Executor to the exact same address

So, yes, this is a no-op, like on other systems.

When writing all the defensive code to not do something that the running 
monitor would disapprove of, it was easier for me to just chuck anything 
to do with either the Executor node or name as opposed to 'allowing' 
them to not change.

I may have to rethink what the right thing to do is.  At the surface, 
not allowing anything to do with the Executor in the incremental update 
list may be all that is necessary.

The full .BIN file is another matter.  If the host is being legitimately 
renumbered and the hobbyist is not paying attention, then you will pull 
the update, put it into the .BIN file, yet never update 
SYSTEM:7-1-CONFIG.CMD, where that kind of change has to go.  At the next 
reboot, the .NDINT will fail and you'll have a subset of nodes, 
depending on where the Executor change is in the .BIN file.

I could certainly auto-magically update the NODE verb in 
SYSTEM:7-1-CONFIG.CMD file, schedule a reboot and send a message.  I 
guess it would depend on the kind of behavior the system administrator 
wanted and the trust relationships.

> ------------------------------------------------------------------------
> On 6/1/21 7:01 AM, Johnny Billquist wrote:
>
> Changing the name of the executor might be objected to by most systems...
> Updating it with the same information it already have should (I hope) 
> be a no-op.
>
> With RSX, the nodename of the executor itself is special, and don't 
> sit together with all to name to number associations for other nodes. 
> So it don't really hit the executor when doing such a clear/purge. I 
> think it's similar with VMS.
>
> But my comment was mainly because the point brought up from Keith that 
> other node information, such as various parameters for DECservers, are 
> also in the database, and you don't want to delete that.
>
> But the commands are "CLEAR NODE * NAME", which means only the name is 
> deleted, not other type of information/parameters in the database. So 
> DECserver information should not be touched in the first place.
>
>
>   Johnny
>> ------------------------------------------------------------------------
>> On 2021-06-01 07:02, Thomas DeBellis wrote:
>>
>> True, but I don't believe you could do that on a Tops-20 cluster.  At 
>> best, it might not be a good idea.
>>
>> No Tops-20 node on the CI will allow a name (or address) redefinition 
>> for itself once booted.  The command would be rejected by the 
>> Executor.  You'd have the situation where nodes would have different 
>> definitions of neighbors because each neighbor's Executor would no 
>> longer have the neighbor's definition.  Or something like that...
>>
>> At Columbia, if we had to do something like that, we brought the 
>> entire cluster down.  This was **really* *frowned on.
>>> ------------------------------------------------------------------------
>>> On 5/31/21 5:17 PM, Johnny Billquist wrote:
>>>
>>> Well, the CLEAR/PURGE is only for the name, not any other 
>>> information...
>>>
>>>   Johnny
>>>
>>>> ------------------------------------------------------------------------
>>>> On 2021-05-31 23:04, Steve Davidson wrote:
>>>>
>>>> Unfortunately CLEAR/PURGE is not a good idea in clusters or nodes 
>>>> that boot DECservers.  VMS requires additional information in the 
>>>> database for those nodes/servers that would be wiped out. That is 
>>>> why I wrote NETUPDATEV2.COM. It does the update without touching 
>>>> any nodes in the local area.
>>>>
>>>> -Steve Davidson
>>>>
>>>> SF:iP1
>>>>> ------------------------------------------------------------------------
>>>>> On May 31, 2021, at 16:49, Keith Halewood 
>>>>> <Keith.Halewood at pitbulluk.org> wrote:
>>>>>
>>>>> With VMS, it's also permissible to copy 
>>>>> sys$system:netnode_remote.dat to other nodes, mainly because no 
>>>>> executor information is contained within this file.
>>>>> Dune::netupdatev3.com is a modified form of the update script 
>>>>> which does a purge/clear by individual area, except for one's own 
>>>>> area which is handled on a node by node basis, including a 
>>>>> configurable range within that area which is ignored. For example, 
>>>>> it prevents MIM:: from overriding 29.100-199 by default.
>>>>>
>>>>> Keith
>>>>>
>>>>> ------------------------------------------------------------------------
>>>>> *From*: owner-hecnet at Update.UU.SE 
>>>>> [mailto:owner-hecnet at Update.UU.SE] On Behalf Of Johnny Billquist
>>>>> *Sent*: 31 May 2021 20:48
>>>>> *To*: hecnet at Update.UU.SE
>>>>> *Subject*: Re: [HECnet] SETNOD, Part 2
>>>>>
>>>>> If there is some additional commands you'd like for me to put into 
>>>>> FIX.T20, let me know.
>>>>>
>>>>> The VMS commandfile I creates starts like this:
>>>>>
>>>>> $ MCR NCP
>>>>> PURGE NODE * NAME
>>>>> CLEAR NODE * NAME
>>>>> def nod 41.28 name 28NH
>>>>>
>>>>>     .
>>>>>     .
>>>>>     .
>>>>>
>>>>> Which means that any previous definitions are first cleared out 
>>>>> before any definitions go in.
>>>>> This is because VMS (and RSX) do not handle if you have a node 
>>>>> name that gets a different address. Clearing things out first 
>>>>> solves that.
>>>>>
>>>>> The alternate thing that can be done in VMS is that you can copy 
>>>>> nodenames from within NCP from another node, which seems to avoid 
>>>>> the problem as well (I think).
>>>>>
>>>>> In RSX, the permanent nodename database in RSX can be created by a 
>>>>> separate tool that does not at all relates to the current nodename 
>>>>> database, so in RSX it's rather easy. You download a new database, 
>>>>> and then you switch it over to the new db.
>>>>>
>>>>> With other systems I don't know at all.
>>>>>
>>>>>    Johnny
>>>>>> ------------------------------------------------------------------------
>>>>>> On 2021-05-31 20:50, Thomas DeBellis wrote:
>>>>>>
>>>>>> I was wondering if anybody would care to explain how routine node 
>>>>>> maintenance happens for DECnet on non-Tops-20 systems.  
>>>>>> Specifically, Johnny's node list on MIM:: changes more or less 
>>>>>> about once a month, sometimes more, sometimes less.
>>>>>>
>>>>>> Is anybody keeping up on this?  How?  I had a (bi-weekly) 
>>>>>> re-occurring batch job which NFT'ed the latest node file from 
>>>>>> MIM:: and simply used SETNOD to shove the whole thing into the 
>>>>>> running monitor, on the assumption that the monitor would figure 
>>>>>> out what to do.  While slapping in the whole list (with .NDINT) 
>>>>>> during timesharing did strike me as somewhat wasteful, I didn't 
>>>>>> pay much attention to the matter as it did work.
>>>>>>
>>>>>> This is mistaken.  Tops-20 will not 'make it' work, nor does it 
>>>>>> apparently detect certain situations which appear to be 
>>>>>> problematic.  It does detect and reject two situations.
>>>>>>
>>>>>>  1. You may not change either the name or address of the host
>>>>>>     (I.E., the Executor).  These can only be set once at boot
>>>>>>     up.  Do other operating systems have this restriction?
>>>>>>  2. You may not change the address of an existing node in the
>>>>>>     local area.
>>>>>>
>>>>>> A node insertion in the local area which usurps an address of 
>>>>>> another node deletes that node.  Outside of the local area, you 
>>>>>> are on your own.  It does whatever you want, which means that you 
>>>>>> can have multiple nodes with the same address.  Is that a 
>>>>>> problem?  On IP4, this would been known as 'aliasing', but I 
>>>>>> don't think DECnet allows this.
>>>>>>
>>>>>> So it would appear that the appropriate behavior is that a new 
>>>>>> node list implies a system reboot.  Unless I'm actively doing 
>>>>>> monitor development, I can't stand doing this.
>>>>>>
>>>>>> However, fixing the problem turned out to be pernicious.  Neither 
>>>>>> of the two cases above is reported to the user program; there is 
>>>>>> no way to determine what might have gone wrong.  There is no way 
>>>>>> for the user program to proactively prevent errors because, while 
>>>>>> you can ask Tops-20 to translate a DECnet address to a node name 
>>>>>> and to verify that a DECnet node name exists, there is no way to 
>>>>>> return the address for a verified DECnet node name.  Is this an 
>>>>>> oversight?  Can a user program get the address of a DECnet node 
>>>>>> name on other operating systems?
>>>>>>
>>>>>> I remediated the low level error reporting issue and implemented 
>>>>>> a new function for NODE% to return the address of an existing 
>>>>>> DECnet node (.NDVFX or Verify Node Extended).  Fixing SETNOD 
>>>>>> proved impossible.  I discovered that the actions to be performed 
>>>>>> were complex enough when automated that the dimensions of the 
>>>>>> solution were wholly beyond its capabilities.  Not that there was 
>>>>>> anything wrong with SETNOD, it just wasn't designed for this kind 
>>>>>> of heavy lift.  So I rewrote it from scratch (cleverly naming it 
>>>>>> SETND2). I'm converging on completion, but I don't work on it 
>>>>>> actively, so this will probably be a few more weeks.
>>>>>>
>>>>>> Here is some sample output; let's suppose that BOINGO needs its 
>>>>>> address changed from 2.399 to 2.400 and that this conflicts with 
>>>>>> another node (in this case, APOLLO).  To get this to work right, 
>>>>>> what you need to do is tell Tops-20 to do is delete BOINGO first, 
>>>>>> so that there is no name clash on the insertion.  Then you have 
>>>>>> to delete APOLLO, so that there is no address conflict.  Once you 
>>>>>> are done performing both these actions, it's safe to do the 
>>>>>> insertion and Tops-20 doesn't reject it or otherwise get itself 
>>>>>> confused.
>>>>>>
>>>>>> @*setnd2*
>>>>>> % Insufficient capabilities for INSERT command
>>>>>>
>>>>>> SETNODE>*vERBOSITY* (level is) *vERBOSE *
>>>>>> Verbosity level is VERBOSE
>>>>>> SETNODE>*get /sECTION-MAP /nO-ACCESS*
>>>>>> [BIN file: TOMMYT:<SYSTEM>NODE-DATA.BIN.91;RESTRICTED-JFN:13 ]
>>>>>> Mapped one section (4 pages), 1778 Words, 889 Nodes.
>>>>>> SETNODE>*recONSTRUCT /sILENT *
>>>>>> [Closed log file: NUL:]
>>>>>> SETNODE>*shoW aREA 2 uNCHANGED*
>>>>>> [Area 2]
>>>>>> A2RTR   ADAGIO  ADVENT  ADVNT5  AMAPUR APOLLO  AUG11   AUGVAX  
>>>>>> BASSET  BEAGLE  BELLS BOINGO  BOXER   BULDOG  CHARON
>>>>>> CODA    COLLIE  CONDOR  CORGI   COYOTE  CYPHER DALMTN  DIVISI  
>>>>>> DOGPAK  ELIDYR  ELITE   FOX GLDRTR  GLOVER  GRUNT
>>>>>> HERMES  HUIA    HUNTER  HUSKY   JACKAL  JENSEN KELPIE  LABRDR  
>>>>>> LAPDOG  LARGO   LEGATO  LENTO MASTIF  MENTOR  MEZZO
>>>>>> MULTIA  MUTT    NO0K    ODST    OINGO   OSIRIS PAVANE  POCO    
>>>>>> POODLE  PUG     PUGGLE  PUPPY R2X899  REACH   SPARK
>>>>>> TERIER  THEARK  TOMMYT  VENTI   WLFHND  WOLF    ZITI
>>>>>> Total nodes in area 2: 67
>>>>>> SETNODE>*shoW **uNCHANGED boiNGO*
>>>>>> BOINGO:: (2.399)
>>>>>> SETNODE>*set 2.400 boingo*
>>>>>> Set existing node BOINGO:: (2.400)
>>>>>> Node BOINGO:: (2.400)
>>>>>> % Removing node BOINGO:: (2.399) from same list to insert in the 
>>>>>> delete list
>>>>>> % Re-using key text for insertion in delete list, BOINGO (2.399)
>>>>>> % Removing BOINGO::'s previous address (2.399)
>>>>>> % Removing node APOLLO:: (2.400) from same list to insert in the 
>>>>>> delete list
>>>>>> % Re-using key text for insertion in delete list, APOLLO (2.400)
>>>>>> % Deleting APOLLO:: (2.400) to reassign its address to BOINGO::
>>>>>> % Allowing update request for node BOINGO:: (2.400) because being 
>>>>>> deleted as (2.399)
>>>>>> % Removing node BOINGO:: (2.399) from unchanged list because its 
>>>>>> address has changed to (2.400)
>>>>>> % Re-using key text for insertion in update list, BOINGO (2.400)
>>>>>> Node change request for BOINGO:: (2.400)
>>>>>> SETNODE>
>>>>>>
>>>>>>
>>>>>
>>>>> -- 
>>>>> 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
>>>
>
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