4 ms·

If it takes an hour to copy a terabyte of data to a tape, put it in a car, drive to a location and read the tape, you just transported 8796093022208 bits in 360

If it takes an hour to copy a terabyte of data to a tape, put it in a car, drive to a location and read the tape, you just transported 8796093022208 bits in 3600 seconds, or about 2443359173 bits/second. edit: I always understood the quote as "the [potential] bandwidth"- the bandwidth that can be available using the station wagon as physical infrastructure.

waqf 16y ago
Firstly, that number is a function of how far apart your particular origin and destination are, so it's not intrinsic to the station wagon. And secondly, you just measured latency there, not bandwidth.
- redthrowaway 16y ago
  Unless I'm wrong, they've measured both: Latency is 1 hour (time it takes a packet to go from source to destination), bandwidth is that number they quoted.
  - regularfry 16y ago
    Latency is greater than 1 hour, if it takes an hour to copy the data to the tapes. You've got to get them to the destination and copy them off after that.
    - redthrowaway 16y ago
      >If it takes an hour to copy a terabyte of data to a tape, put it in a car, drive to a location and read the tape That's 1 hr latency, unless I'm mistaken. Latency doesn't include disk operations on the client side, does it? Is latency time between a signal being sent and received, or between sent, received, and acknowledgement sent/received? ie, is latency time(client->SYN->server->SYNACK->client->ACK->server), or time(client->SYN->server)?
      - regularfry 16y ago
        Bah. My reading comprehension not so good.
  - waqf 16y ago
    Latency is 1 hour, but to get bandwidth you need to divide not by 1 hour but by the time between successive station wagon departures. For example if you only have one station wagon and driving back after copying the tapes takes a further 30 minutes, then the denominator is 5400 seconds and so the system bandwidth is 50% less than the number quoted.

waqf 16y ago

Firstly, that number is a function of how far apart your particular origin and destination are, so it's not intrinsic to the station wagon. And secondly, you just measured latency there, not bandwidth.

redthrowaway 16y ago
Unless I'm wrong, they've measured both: Latency is 1 hour (time it takes a packet to go from source to destination), bandwidth is that number they quoted.
- regularfry 16y ago
  Latency is greater than 1 hour, if it takes an hour to copy the data to the tapes. You've got to get them to the destination and copy them off after that.
  - redthrowaway 16y ago
    >If it takes an hour to copy a terabyte of data to a tape, put it in a car, drive to a location and read the tape That's 1 hr latency, unless I'm mistaken. Latency doesn't include disk operations on the client side, does it? Is latency time between a signal being sent and received, or between sent, received, and acknowledgement sent/received? ie, is latency time(client->SYN->server->SYNACK->client->ACK->server), or time(client->SYN->server)?
    - regularfry 16y ago
      Bah. My reading comprehension not so good.
- waqf 16y ago
  Latency is 1 hour, but to get bandwidth you need to divide not by 1 hour but by the time between successive station wagon departures. For example if you only have one station wagon and driving back after copying the tapes takes a further 30 minutes, then the denominator is 5400 seconds and so the system bandwidth is 50% less than the number quoted.