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From: art@MITRE.ARPA.UUCP
Newsgroups: comp.os.vms
Subject: Re: Changing from daylight time to standard time
Message-ID: <8710261949.AA27619@mitre.arpa>
Date: Mon, 26-Oct-87 14:49:13 EST
Article-I.D.: mitre.8710261949.AA27619
Posted: Mon Oct 26 14:49:13 1987
Date-Received: Sat, 31-Oct-87 02:40:43 EST
References: <946@nmtsun.nmt.edu>
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The MITRE Corp., Washington, D.C.
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I have changed time on a system which had accounting running.  Yes I had people
who were charged for large amounts of connect time.  I know of no one being 
charged for an hour of CPU time.  Clearly the person to receive this charge
if any one does, would be the account of the person who was executing at the
instant that the clock changed.  This would be the system manager.  However, I
understand that CPU time is billed on a clock tick basis to the person that
has the cpu at the time the clock ticks.  It only increments a counter.  It
would be two costly to take differences between the clocks at the begining
and end of the cpu usage.

The accounting package also will give a negative connect time for those
logged in during the Fall time change.  This was actually the way that we
found out about the problem.  A user received a credit for his usage for the
month after we corrected the CPU time.  A DEC CE had entered the wrong year
and we were up and running before the mistake was noticed.  Correcting the
time resulted in changing the year back by one.  This resulted in a seventeen
thousand dollar credit for everyone who was logged in.  We charge $2.00 per
hour of connect time.  Which for 365 days came to $17,520.  No one received a
CPU credit.

I will second the motion that it is best to take the system down.  Second best
is to halt accounting and restart accounting after you change the time.


 
     
*
*---Art
*
*Arthur T. McClinton Jr.     ARPA: ART@MITRE.ARPA
*Mitre Corporation MS-Z305   Phone: 703-883-6356
*1820 Dolley Madison Blvd    Internal Mitre: ART@MWVMS or M10319@MWVM
*McLean, Va. 22102           DECUS DCS: MCCLINTON
*

  =-=- This note is in response to yours which follows -=-=

In article <8710241907.AA29503@ucbvax.Berkeley.EDU>, R021JM9W@VB.CC.CMU.EDU (Ji
  m Murawski) writes:
> 
>         In most of North America, standard time starts this Sunday
>         (October 25th) at 2:00.  
>	[ much verbage deleted ]
How about the command(s) :

$ SET TIME="+01:00:00"		! In the fall
$ SET TIME="-01:00:00"		! In the spring

These work well and are much faster/easier to understand (they also work
interactively.)

	One point I'd like to get straighten out.  I've done this a few time,
and have had no problems, but I'm not sure if it is cool.  I have heard horror
stories about people getting charged for one hour of cpu time when the system
manager change the time on them.  Has this ever happened to anyone under VMS?
If so, then is there a better way of doing daylight savings stuff.  I know
this can mess up connect times, if your accounting software isn't smart enough,
but we don't charge for connect time.


				Warner Losh