[tahoe-dev] tahoe over satellite

zooko zooko at zooko.com
Fri Jun 20 20:49:09 UTC 2008


On Jun 20, 2008, at 12:12 PM, Aleksandr Milewski wrote:

> Those are precisely the sorts of network conditions we were designing
> for both at DF and later at Aspera. I'm actually very surprised things
> are working as well as they are, since TCP is mostly useless under
> those conditions.

Yeah, the throughput it terrible for large files.  The first large  
file just finished:


(more details appended)

We could improve this behavior (as well as the behavior in the more  
common case) by implementing pipelining -- ticket #392.  We can see  
that this makes a difference in the common case because the graphs of  
the upload rate for immutable files changed dramatically when we  
reduced the share size from 1 MiB to 128 KiB, in March:

http://allmydata.org/tahoe-figleaf-graph/hanford.allmydata.com- 
tahoe_speedstats_rate.html

Regards,

Zooko

tickets mentioned in this e-mail:

http://allmydata.org/trac/tahoe/ticket/392 # pipeline upload segments  
to make upload faster

                                File Upload Status

      * Started: 10:54:48 20-Jun-2008
      * Storage Index: xjnmcvpxwbe33fs5ldyqf2c76u
      * Helper?: No
      * Total Size: 27529494
      * Progress (Hash): 100.0%
      * Progress (Ciphertext): 100.0%
      * Progress (Encode+Push): 100.0%
      * Status: Done

Upload Results

      * Shares Pushed: 10
      * Shares Already Present: 0
      * Sharemap:
           * 0 -> Placed on [7tlov7eg]
           * 1 -> Placed on [trjdor3o]
           * 2 -> Placed on [lwkv6cji]
           * 3 -> Placed on [2y7ldksg]
           * 4 -> Placed on [xiktf6ok]
           * 5 -> Placed on [ivjakubr]
           * 6 -> Placed on [6fyx5u4z]
           * 7 -> Placed on [sgh4c5cr]
           * 8 -> Placed on [uf7kq2sv]
           * 9 -> Placed on [wfninubk]
      * Servermap:
           * [ivjakubr] got share: #5
           * [lwkv6cji] got share: #2
           * [sgh4c5cr] got share: #7
           * [trjdor3o] got share: #1
           * [uf7kq2sv] got share: #8
           * [wfninubk] got share: #9
           * [xiktf6ok] got share: #4
           * [2y7ldksg] got share: #3
           * [6fyx5u4z] got share: #6
           * [7tlov7eg] got share: #0
      * Timings:
           * File Size: 27529494 bytes
           * Total: 10325.49s (2.7kBps)
                * Storage Index: 462ms (59.50MBps)
                * [Contacting Helper]:
                     * [Helper Already-In-Grid Check]:
                * [Upload Ciphertext To Helper]: ()
                * Peer Selection: 25.50s
                * Encode And Push: 10299.53s (2.7kBps)
                     * Cumulative Encoding: 3.64s (7.56MBps)
                     * Cumulative Pushing: 10080.89s (2.7kBps)
                     * Send Hashes And Close: 203.30s
                * [Helper Total]:
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