March topic(s) for BLU
John Chambers
jc at trillian.mit.edu
Sat Mar 3 14:40:02 EST 2007
Matt Shields wrote:
| Maybe since we're all linux geek we should use a unix timestamp that's UTC
Actually, that's really a "network geek" thing. Of course, there's a
big overlap. But I've often found myself setting my TZ to UTC0 just
to make network stuff simpler.
Funny story: Back in the late 80's, I worked in a lab that had the
fun of testing a package of networking stuff from 3Com. It included
what was supposed to be some high-precision clock sync tools. It
turned out that we were their first customers that had a LAN that
crossed multiple time zones. We had machines on our "internal" LAN on
both the east and west coast. We found that at random times, all the
machines on the east coast would jump to Pacific time. We'd fix that,
and a while later, all the machines on the west coast would jump to
Eastern time.
We looked at the messages with a line monitor, and found that the
clock messages were sent in ASCII, which made them easy to decode.
They were local time, with no time zone field. Oops. I sent in a bug
report suggesting that, to save the sanity of their programmers, they
shouldn't add a time zone; they should make the timestamps all UTC.
This was apparently a bit of a radical concept to some of them, but
they eventually did it. It took a few weeks though, so I suspected
that they had to learn the hard way that local time just won't work
in such tasks.
There's also the observation that back in the early 70's, before unix
escaped from Bell Labs, the guys there had already decreed that
unix's internal clock would always be GMT. A century's experience
with the phone system had taught them that that's the only sensible
clock for a system that spans time zones. It's fun to watch people
relearn this lesson over and over, as things move onto the Net.
--
_'
O
<:#/> John Chambers
+ <jc at trillian.mit.edu>
/#\ <jc1742 at gmail.com>
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