Changes between Version 2 and Version 3 of ServerSelection
- Timestamp:
- 2009-10-19T18:12:32Z (15 years ago)
Legend:
- Unmodified
- Added
- Removed
- Modified
-
ServerSelection
v2 v3 21 21 22 22 However, there are some additional properties that need to be satified by the 23 se ver-selection algorithm for it to work at all. The basic Tahoe model is23 server-selection algorithm for it to work at all. The basic Tahoe model is 24 24 that the filecap is both necessary and sufficient (given some sort of grid 25 25 membership) to recover the file. This means that the eventual 26 26 '''downloader''' needs to be able to find the same servers, or at least have 27 a sufficiently -high probability of finding "enough" servers within a27 a sufficiently high probability of finding "enough" servers within a 28 28 reasonable amount of time, using only information which is found in the 29 29 filecap. … … 38 38 39 39 Another potential goal is for the download process to be tolerant of new 40 servers, removed servers, and shares whichhave been moved (possibly as the40 servers, removed servers, and shares that have been moved (possibly as the 41 41 result of repair or "rebalancing"). Some use cases will care about this, 42 42 while others may never change the set of active servers and won't care. 43 43 44 44 It's worth pointing out the properties we were trying to get when we came up 45 with the current " tahoe2" algorithm:45 with the current "TahoeTwo" algorithm: 46 46 47 47 * for mostly static grids, download uses minimal do-you-have-share queries … … 53 53 bytes-per-second, even if serverids are not uniformly distributed 54 54 55 We picked the pseudo-random permuted serverlist to get these properties. I'd56 love to be able to get stronger diversity among hosts, racks, or data 57 centers, but I don't yet know how to get that '''and''' get the properties 58 listed above, while keeping the filecaps small.55 We picked the pseudo-random permuted serverlist [dependent on the StorageIndex] 56 to get these properties. I'd love to be able to get stronger diversity among 57 hosts, racks, or data centers, but I don't yet know how to get that '''and''' 58 get the properties listed above, while keeping the filecaps small.