words to live by
pkern
"Never underestimate the bandwidth of a
station wagon full of tapes."
- some wise words from
Dr. Warren Jackson, Director, UTCS
Rob Warnock
Reminds me of a calculation done a few years ago, on the cost-effectiveness
of 56kb lines for heavy batch transfer cross-country. My numbers may be off
a bit, but you'll get the idea:
A. One 56kb line (clean, low errors) with fairly large block sizes
(say, 90% efficiency) can move about 550 Mbytes per 24 hours,
and costs about $1.50/mi/mo (???) or (for 2000 miles) about
$3000/mo plus about $1500/end/mo for modems or about $6000/mo
or $200/day, which is about $0.37 per megabyte.
Average data rate is about 50 kbit/sec; latency for a 1 Mbyte
transfer is a little over 2.5 minutes.
B. Using 2400 foot magtapes with large blocks (say, 90% efficiency)
at 6250 bpi, you can fit about 180 Mbyte/magtape. Three (3) of
those is about 540 Mbyte [same as 56kb line per day]. You can
send a parcel of three tapes by Federal Express (or equiv.)
every day at less than $50/parcel, or $50/day, or $0.09/Mbyte.
Average data rate is 50 kbit/sec; latency (1 Mbyte) is 24 hours.
[Open question: What is the shape of the weight/cost curve?
How many pounds or cubic feet can you ship in one 24-hour parcel?
I.e., is there a better ($$$/Mbyte) size than 3 tapes/parcel?]
Adding the case of the station wagon [above], we get:
C. A medium-small station wagon (say, like my VW dasher) can hold
at least 25 cartons of a dozen tapes, or 300 tapes, or 162 Gbyte.
With a cross-country travel time of 40-48 hours (55 mph, 2 drivers,
minimal stops), running three shifts of station wagons might cost
(say) $1600/48hrs (6 salaries @ $30k + $1.50/gal @ 27mpg +
depreciation @ $0.20/mi) or about $0.01/Mbyte.
Average data rate is 15 Mbit/sec, latency (1 Mbyte) is 48 hours.
D. Use cargo vans, 10 times as many tapes, double the expense, and
get roughly $0.002/Mbyte.
Average data rate is 150 Mbit/sec, latency (1 Mbyte) is 48 hours.
So the latency/bandwidth tradeoff holds "in the large", as well. I suspect,
however, that using larger packages in a "Federal Express" mode (say, using
some of the "Second Day" delivery services) could be as cost-effective as
the station wagon, with the same latency.
Anybody got any useful (i.e., current) cost numbers on a 2000 mile T-1
circuit, for comparison? It would be interesting to compare both land lines
and satellite circuits vis-a-vis the station wagon or parcel delivery.
Lest this be considered totally a joke, though it is humorous, has anybody
thought about sending USENET traffic via magtape and FedEx? How does it
compare to your phone bill? What is the effect on latency? What is the
effect on Stargate? ;-} I mean, with traffic still under a meg a day,
and with special delivery letters at $2-3 each (depending on weight),
we could USnail FLOPPIES and still win! And you don't have to worry about
your disks filling up while you're on vacation! Your mailbox will hold WEEKS
of floppies! ;-} And you don't have to worry about rnews tying up uuxqt or
(alternatively) flooding your system with inews'es...
Hmmm... maybe that's how we handle the flood of PCs that are about to
hit the net... offer them a cost-effective netnews floppy replication
and distribution service! You receive in the mail; you send with a modem
or (cheaper) just use mail. Make copies for your friends! Or put the
floppies inside the back cover of "NET Magazine: The Weekly Digest of
the Highlights of USENET (with commentaries by noted net authors, critics,
and flamers)"!
I noticed in a bookstore the other day that at least one magazine
is already being published in floppy format. 'S truth!
Rob Warnock
Systems Architecture Consultant
UUCP: {ihnp4,ucbvax!dual}!fortune!redwood!rpw3
DDD: (415)572-2607
USPS: 510 Trinidad Lane, Foster City, CA 94404
Frank Crawford
> | "Never underestimate the bandwidth of a
> | station wagon full of tapes."
> | - some wise words from
> | Dr. Warren Jackson, Director, UTCS
> +---------------
>
> thought about sending USENET traffic via magtape and FedEx? How does it
> compare to your phone bill? What is the effect on latency? What is the
> effect on Stargate? ;-} I mean, with traffic still under a meg a day,
> and with special delivery letters at $2-3 each (depending on weight),
> we could USnail FLOPPIES and still win! And you don't have to worry about
> your disks filling up while you're on vacation! Your mailbox will hold WEEKS
> of floppies! ;-} And you don't have to worry about rnews tying up uuxqt or
> (alternatively) flooding your system with inews'es...
>
Yes, that's all sounds good, but you still haven't worked out
how to stop new being lost. I don't know what the mail system's like
in the US but in Aust. no matter how you sent it some would be lost or
at least delayed for an extended period of time.
Actually from what I have seen that's probably no different to
the current situation.
Frank Crawford
ACSnet: fr...@aaec.OZ
UUCP: ...{decvax,vax135,eagle,pesnta}!mulga!aaec.OZ!frank
(or the ACSnet address above)
byer
> | "Never underestimate the bandwidth of a
> | station wagon full of tapes."
> | - some wise words from
> | Dr. Warren Jackson, Director, UTCS
> +---------------
for multi-Mbyte X-C data transfers.
While mention was made of FedEx being one possibility, and they sure
do provide good service, it is fairly expensive. Anyone investigating
express shipments is surely aware of the other alternatives, including
USPS Express Mail. Well, there is another flavor of Express Mail
called ``Label C'' which is for Airport-to-Airport service with
shipment made on the next flight out, usualy getting point-to-point
the same day. The price is $6.15 for two pounds, $10-16 for 10 lbs.
and $17-34 for 25 lbs. (variation based on `zones').
This might provide maximum cost-effectiveness in the volume/latency/cost
matrix.
Brent Byer (harvard!wjh12!bb)
``We are the other people -- you're the other people, too.''
Barry Shein
Re: Re: Problem is Post Office lossage
You mention that you are not in the US, the US Mail is not in my
experience very bad about reliability (I know, flame flame, but really,
about 99.9% gets where it's supposed to w/in 2 or 3 days.) The
alternative exists for a dollar or two to special handling which ups
reliability considerably (again, favorite horror anecdote to /dev/null,
its rare, not rare enough, but rare.) Also, so it got lost once a year,
so you get another copy sent, this gets closer to the real problem...
WHO EXACTLY IS GOING TO SIT AND MAKE THESE FLOPPIES? The beauty of the
current scheme is that while all good children are asleep (or up
hacking) the news gets silently delivered, a phone is dialed, a phone is
answered, chug chug, done. Yes, there is maintenance involved, but I
doubt this will reduce it for the SUPPLIER sites (someone still has to
keep it coming in to get it onto floppies.)
If someone is willing to copy floppies, god bless 'em, I think tho this
is the major stumbling block to the scheme unless a data-duplication
service is involved which probably puts the price back to where you
started.
However, for example, if one site would feed a foreign site who would in
turn UUCP to local sites (eg. transatlantic) this might be made to work,
but I doubt that is what people are talking about.
-Barry Shein, Boston University
Henry Spencer
> current scheme is that while all good children are asleep (or up
> hacking) the news gets silently delivered, a phone is dialed, a phone is
Speaking as somebody whose original network connection was *manually*
dialed for about a year until we got an autodialer, Barry's got a point.
Our manual dialing ended three years ago, and I *still* break out in
smiles every time I hear the autodialer clicking away...
--
Henry Spencer @ U of Toronto Zoology
{allegra,ihnp4,linus,decvax}!utzoo!henry
jad
> Yes, that's all sounds good, but you still haven't worked out
> in the US but in Aust. no matter how you sent it some would be lost or
> at least delayed for an extended period of time.
One possibility is to have a dedicated service to do this ...
perhaps it would be cheaper to hire someone to run tapes back
and forth from city to city. (FedEx was the original
suggestion, and that's about all they do, pretty reliably, too).
But what am I saying? This seems like a huge step backwards.
Never underestimate the bandwidth of a boatload of tapes, but
think about propagation delay, and the incredible hassles
associated with loading a boatload of tapes onto tape drives.
Arrrgh. TCP/IP, on the other hand, ain't so bad ...
-- jad --