From: kaike pan
Subject: Re: Delayed Slew On 54498
Date: Wed, 6 Feb 2008 11:14:00 -0700
     I want to clarify one thing here. The rebooting did not cause
any science time loss.
The MCP rebooting process took less than 1 minute and was done in the
afternoon
check out.
  As a rule, if there will be a science time loss and we are not very
sure one machine is
the cause of the problem, we will not reboot it.  However, if it will
not cause any science
time loss and one observer thinks that one machine may be the cause,
we may try to
reboot the machine in the afternoon because it's not harmful to
reboot a computer.
On average, I will say we reboot one machine every two weeks (except
for DA crates which
hang on more often, and we usually know when they need to be
rebooted). Given number
of computers we have there, this is one reboot every 5 months or so
per computer. It is fair
to state that observers applied their adjustment well so far. There
is a good number of times
that rebooting a computer made problems disappear (fixed or
coincidences?) although we
did not fully understood the problem because of the complexion of the
whole system.
   Thanks to Dan for tracking down the slew delay was due to the
delay between sop
session and the TCC.
Robert, Dan:  any further clue on this. What cause the delay between
sop and TCC?
what can be done to fix it if this happen again? Thanks!
   -kaike
On Feb 5, 2008, at 6:38 AM, Robert Lupton the Good wrote:
>>   Since the delay appeared to be between that one sop session and
>> the TCC and not between the TCC and mcp, I think the rebooting of
>> the mcp and the lack of delay since is probably just coincidence.
>
> Let me reiterate this. When I first saw the mail I was pretty sure
> that the mcp
> was innocent;  Dan did the right thing -- he investigated what
> really happened.
>
> Computers are not magic black boxes!  Please think about what might
> have
> happened, and think about how you could analyse the problems.
> Rebooting
> doesn't usually do any harm (although it takes time), but I see too
> many
> logs about rebooting machines that are CLEARLY not causing the
> problem.
>
> 					R
>
>
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