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Delays on AMSAT-BB



At 6:25 AM -0600 3/10/03, Jon Ogden wrote:
>Bruce, it's not 15 to 30 minutes.  It's more like HOURS.  This is one of the
>slowest lists that I have seen.

Bruce's number is a lot closer to the truth.

I analyzed yesterday's log file for messages delivered to AMSAT-BB 
and extracted a histogram of the delay between posting and message 
delivery. You can see the results here:

http://www.amsat.org/amsat/kb5mu/bbdelay.gif

You can see from this chart that within about 40 minutes the vast 
majority of deliveries have been completed. This is a composite of 
the 26 AMSAT-BB messages posted yesterday. Each occurrence represents 
successful delivery of one message to one host (which may support 
multiple subscribers).

The small uptick you see around one hour is caused by retries. If the 
first delivery does not succeed for one reason or another, and also 
does not fail conclusively, the second attempt is made after one hour.

The delays charted here don't include the time it takes for a message 
to get from the sender to amsat.org, or the time it takes for the 
recipient's host to make the message available in the user's mailbox. 
These delays are typically just a few seconds, but can be longer in 
some cases.

Messages can also be delayed if they trigger a filter for manual 
review. For example, a message that resembles a "subscribe" or 
"unsubscribe" request is trapped for manual review, because sending 
such a request to the mailing list is a common mistake. Manual review 
can add many hours of delay, of course.


On the non-technical side, I wish to point out that most subscribers 
probably don't sit by their computers waiting for AMSAT-BB messages 
to arrive. Most probably read messages once a day, or less. Digest 
subscribers (currently about one quarter of all subscribers) 
certainly do. That means that if you post a message that will be 
obsolete within an hour or so, most people won't see it until it's 
too late, even if the delay through the system is zero.

73  -Paul
kb5mu@amsat.org
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