[tahoe-dev] tahoe over satellite

[zooko]

Folks:

I'm uploading lots of pictures and movies from my mom's farmhouse.   
Her Internet connection is through a geostationary satellite owned by  
a company named "WildBlue".  When we're not doing too much with it,  
we get ping times like this:

28 packets transmitted, 26 packets received, 7% packet loss
round-trip min/avg/max/stddev = 1155.724/1428.105/1756.191/169.410 ms

When I'm heavily loading it by doing many simultaneous Tahoe uploads  
and downloads as well as ssh and other web requests, we get ping  
times like this:

49 packets transmitted, 44 packets received, 10% packet loss
round-trip min/avg/max/stddev = 2740.267/3571.314/4553.213/493.893 ms

It is interesting to see how Tahoe handles these unusually large  
round trip times and unusually large packet loss.  In general, it  
handles it simply by being patient -- there are no timeouts, fail- 
overs or other mode changes that occur in response to this network  
behavior.

Here are a few statistics results from my local Tahoe node -- a  
directory update (completed), and a download in progress.

                           Mutable File Publish Status

      * Started: 11:17:32 20-Jun-2008
      * Storage Index: mmn63ajdghwqnen6o546icgvim
      * Helper?: No
      * Current Size: 1382
      * Progress: 100.0%
      * Status: Done

Retrieve Results

      * Encoding: 3 of 10
      * Sharemap:
           * 0 -> Placed on [wy7w3sls]
           * 1 -> Placed on [xiktf6ok]
           * 2 -> Placed on [trjdor3o]
           * 3 -> Placed on [fcmlx6em]
           * 4 -> Placed on [wfninubk]
           * 5 -> Placed on [ckpjhpff]
           * 6 -> Placed on [2y7ldksg]
           * 7 -> Placed on [6fyx5u4z]
           * 8 -> Placed on [q5l37rle]
           * 9 -> Placed on [sgh4c5cr]
      * Timings:
           * Total: 33.36s (41Bps)
                * Setup: 369us
                * Encrypting: 72us (19.19MBps)
                * Encoding: 87us (15.71MBps)
                * Packing Shares: 35ms (39.0kBps)
                     * RSA Signature: 33ms
                * Pushing: 33.32s (41Bps)
           * Per-Server Response Times:
                * [ckpjhpff]: 15.09s
                * [fcmlx6em]: 25.77s
                * [q5l37rle]: 20.63s
                * [sgh4c5cr]: 34ms
                * [trjdor3o]: 25.50s
                * [wfninubk]: 31.48s
                * [wy7w3sls]: 7.18s
                * [xiktf6ok]: 33.32s
                * [2y7ldksg]: 17.57s
                * [6fyx5u4z]: 24.22s
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                               File Download Status

      * Started: 11:15:24 20-Jun-2008
      * Storage Index: uv7kpwj6v4hkwfhuzlacw5jgve
      * Helper?: No
      * Total Size: 113554221
      * Progress: 5.3%
      * Status: Downloading segment 47 of 867

Download Results

      * Servers Used: [xiktf6ok], [trjdor3o], [q5l37rle]
      * Servermap:
           * [ckpjhpff] has share: #8
           * [fcmlx6em] has share: #5
           * [lwkv6cji] has share: #9
           * [q5l37rle] has share: #6
           * [trjdor3o] has share: #7
           * [uf7kq2sv] has share: #1
           * [wfninubk] has share: #0
           * [xiktf6ok] has share: #2
           * [2y7ldksg] has share: #3
           * [7tlov7eg] has share: #4
      * Timings:
           * File Size: 113554221 bytes
           * Total: ()
                * Peer Selection: 33.99s
                * UEB Fetch: 7.13s
                * Hashtree Fetch: 3.65s
                * Segment Fetch: ()
                     * Cumulative Fetching: 1395.52s (81.4kBps)
                     * Cumulative Decoding: 33ms (3429.94MBps)
                     * Cumulative Decrypting: 635ms (178.63MBps)
                * Paused by client: 0us
           * Per-Server Segment Fetch Response Times:
                * [q5l37rle]: 5.85s, 7.94s, 10.22s, 10.83s, 8.79s,  
6.11s,
                  2.94s, 6.99s, 12.19s, 18.08s, 10.55s, 9.07s,  
17.86s, 26.49s,
                  2.35s, 6.14s, 7.50s, 8.89s, 10.31s, 28.59s, 2.33s,  
3.34s,
                  7.19s, 12.86s, 10.56s, 19.14s, 1.92s, 2.37s, 8.72s,  
5.02s,
                  8.33s, 8.67s, 8.55s, 16.23s, 4.29s, 7.24s, 7.28s,  
9.68s,
                  4.21s, 2.89s, 4.24s, 13.57s, 7.23s, 3.56s, 19.65s,  
7.36s,
                  6.65s
                * [trjdor3o]: 37.12s, 35.54s, 27.57s, 27.41s, 11.26s,  
12.08s,
                  11.62s, 7.03s, 20.03s, 32.34s, 18.47s, 22.98s, 27.87s,
                  38.52s, 15.31s, 6.19s, 9.38s, 10.50s, 37.48s, 30.39s,
                  13.95s, 10.28s, 21.23s, 14.55s, 14.90s, 20.84s, 2.02s,
                  5.39s, 11.04s, 5.07s, 16.83s, 23.25s, 8.68s,  
25.65s, 17.63s,
                  22.17s, 26.57s, 44.66s, 10.80s, 33.90s, 14.72s,  
14.82s,
                  29.48s, 3.70s, 37.88s, 21.56s
                * [xiktf6ok]: 67.08s, 34.63s, 29.03s, 15.74s, 17.35s,  
15.79s,
                  31.65s, 22.71s, 31.81s, 45.63s, 14.83s, 17.14s,  
25.75s,
                  33.62s, 27.52s, 30.70s, 34.56s, 34.06s, 30.21s,  
32.83s,
                  30.59s, 31.02s, 29.23s, 38.74s, 28.72s, 23.40s,  
15.23s,
                  15.13s, 30.82s, 22.61s, 29.38s, 22.66s, 16.33s,  
40.87s,
                  32.62s, 35.30s, 36.10s, 34.96s, 12.08s, 45.91s,  
30.44s,
                  34.83s, 19.97s, 3.51s, 49.49s, 36.60s
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