[time-nuts] Lost GPS lock or 1PPS recently?

Didier Juges shalimr9 at gmail.com
Sun Sep 9 22:41:12 EDT 2018


Not a time-nut issue but most banks that batch process will process the
debits before the credit so that they get to charge you no matter what.
They probably don't all do it but some definitely do. I had one bank even
charge me multiple overdraft fees because they processed the largest checks
first, before the smaller ones in order to get my balance negative before
processing the smaller checks in order to maximize the fees. If the
transactions had been processed in the actual order, there would have been
no overdraft fee.
When I asked, they said the debits were processed electronically
(immediately) but the deposits (which I made by cash at the front desk)
were sent to a central office across the state BY MAIL for reconciliation,
and therefore processed (and credited to my account) several days later. I
did not remain a customer very long after that.
They closed in the 90s when it was revealed they were laundering money for
major drug traffickers.

But I see your point :)


On Sep 8, 2018 9:26 AM, "jimlux" <jimlux at earthlink.net> wrote:

On 9/7/18 10:05 PM, John Reid wrote:
> Hi all,
>
>
> discussion of how to keep accurate time without access to GPS seems very
> on topic to me.
>
>
> These people involved in major catastrophe ('end of the world' as you
> put it) scenarios have a wealth of experience in other ways of keeping
> accurate time.
>


Actually, they don't necessarily have a wealth of experience, because
they may have marched themselves down a path where they have a
*requirement* for much better timing than they realize, because it is so
easy and cheap to get good time today.

Imagine this scenario - you're a bank, and you batch process checks and
deposits in one physical location, so you don't much care about when the
check was written or the deposit made.  Then you move to a distributed
system across the US, where the reconciliation is done on the basis of
the date of the transaction - still probably ok, because there are no
transactions during non-business hours, so as long as you reconcile at
1AM, if transaction time stamps are off by 5 minutes, it doesn't matter.


Now say "we're going to charge you, the customer a fee, if your balance
goes negative" and go to 24/7 operations, where transactions are
journaled immediately, rather than batch processed at night  If a
deposit that was made at 12:00 (but timestamped 12:05)  is followed by a
withdrawal made at 12:03 (but timestamped 12:00), you get unfairly
charged the overdraft fee.

For small problems, banks have ways to "unwind" errors.  But if it
becomes a systemic thing that's a problem.

So the bank sets up GPSDOs at each transaction point - problem solved.

Until GPS fails.




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