tahoe-lafs/trac-2024-07-25
2
0
Issues 1.1k Wiki Activity

s/allmydata.org/tahoe-lafs.org/ 

[Imported from Trac: page ServerSelection, version 13]
zooko 2011-04-26 12:23:22 +00:00
parent b7acf6f147
commit beeec4337a
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
ServerSelection.md

@ -9,7 +9,7 @@ Different users of Tahoe-LAFS have different desires for "Which servers should I
* Some people -- I'm sorry I forget who -- have said they want to upload at least K shares to the K fastest servers.
* Jacob Appelbaum and Harold Gonzales want to specify a set of servers which collectively are guaranteed to have at least K shares -- they intend to use this to specify the ones that are running as Tor hidden services and thus are attack-resistant (but also extra slow-and-expensive to reach). Interestingly the server selection policy on *download* should be that the K servers which are Tor hidden services should be downloaded from as a last resort.
* Several people -- again I'm sorry I've forgotten specific attribution -- want to identify which servers live in which cluster or co-lo or geographical area, and then to distribute shares evenly across clusters/colos/geographical-areas instead of evenly across servers.
* Here's an example of this desire, Nathan Eisenberg asked on the mailing list for "Proximity Aware Decoding": <http://allmydata.org/pipermail/tahoe-dev/2009-December/003286.html>
* Here's an example of this desire, Nathan Eisenberg asked on the mailing list for "Proximity Aware Decoding": <http://tahoe-lafs.org/pipermail/tahoe-dev/2009-December/003286.html>
* If you have *K+1* shares stored in a single location then you can repair after a loss (such as a hard drive failure) in that location without having to transfer data from other locations. This can save bandwidth expenses (since inter-location bandwidth is typically free), and of course it also means you can recover from that hard drive failure in that one location even if all the other locations have been stomped to death by Godzilla.
As I have emphasized a few times, we really should not try to write a super-clever algorithm into Tahoe which satisfies all of these people, plus all the other crazy people that will be using Tahoe-LAFS for other things in the future. Instead, we need some sort of configuration language or plugin system so that each crazy person can customize their own crazy server selection policy. I don't know the best way to implement this yet -- a domain specific language? Implement the above-mentioned list of seven policies into Tahoe-LAFS and have an option to choose which of the seven you want for this upload? My current favorite approach is: you give me a Python function. When the time comes to upload a file, I'll call that function and then use whichever servers it said to use.