tahoe-lafs/roadmap.txt

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['*' means complete]
Connection Management:
*v1: foolscap, no relay, live=connected-to-introducer, broadcast updates, fully connected topology
*v2: configurable IP address -- http://allmydata.org/trac/tahoe/ticket/22
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v3: live != connected-to-introducer, connect on demand
v4: relay?
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File Encoding:
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*v1: single-segment, no merkle trees
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*v2: multiple-segment (LFE)
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*v3: merkle tree to verify each share
*v4: merkle tree to verify each segment
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v5: merkle tree on plaintext (and crypttext?): incremental validation
v6: only retrieve the minimal number of hashes instead of all of them
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Share Encoding:
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*v1: fake it (replication)
*v2: PyRS
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*v2.5: ICodec-based codecs, but still using replication
*v3: C-based Reed-Solomon
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URI:
*v1: really big
v2: derive more information from version and filesize, to remove codec_name,
codec_params, tail_codec_params, needed_shares, total_shares, segment_size
Upload Peer Selection:
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*v1: permuted peer list, consistent hash
*v2: permute peers by verifierid and arrange around ring, intermixed with
shareids on the same range, each share goes to the
next-clockwise-available peer
v3: reliability/goodness-point counting?
v4: denver airport (chord)?
Download Peer Selection:
*v1: ask all peers
v2: permute peers and shareids as in upload, ask next-clockwise peers first
(the "A" list), if necessary ask the ones after them, etc.
v3: denver airport?
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Filetable Maintenance:
*v1: vdrive-based tree of MutableDirectoryNodes, persisted to vdrive's disk
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no accounts
v2: filetree, one space per user, plus one global mutable space
v3: maintain file manifest
v4: figure out accounts, users. Maybe implement SSKs
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Checker/Repairer:
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*v1: none
v1.5: maintain file manifest
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v2: centralized checker, repair agent
v3: nodes also check their own files
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Storage:
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*v1: no deletion, one directory per verifierid, no owners of shares,
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leases never expire
*v2: multiple shares per verifierid [zooko]
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v3: disk space limits on storage servers -- http://allmydata.org/trac/tahoe/ticket/34
v4: deletion
v5: leases expire, delete expired data on demand, multiple owners per share
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UI:
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*v1: readonly webish (nevow, URLs are filepaths)
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*v2: read/write webish, mkdir, del (files)
v2.5: del (directories)
v3: PB+CLI tool.
v3.25: XML-RPC
v3.5: XUIL?
v4: FUSE -- http://allmydata.org/trac/tahoe/ticket/36
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Operations/Deployment/Doc/Free Software/Community:
- move this file into the wiki ?
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back pocket ideas:
when nodes are unable to reach storage servers, make a note of it, inform
verifier/checker eventually. verifier/checker then puts server under
observation or otherwise looks for differences between their self-reported
availability and the experiences of others
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store filetable URI in the first 10 peers that appear after your own nodeid
each entry has a sequence number, maybe a timestamp
on recovery, find the newest
multiple categories of leases:
1: committed leases -- we will not delete these in any case, but will instead
tell an uploader that we are full
1a: active leases
1b: in-progress leases (partially filled, not closed, pb connection is
currently open)
2: uncommitted leases -- we will delete these in order to make room for new
lease requests
2a: interrupted leases (partially filled, not closed, pb connection is
currently not open, but they might come back)
2b: expired leases
(I'm not sure about the precedence of these last two. Probably deleting
expired leases instead of deleting interrupted leases would be okay.)
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big questions:
convergence?
peer list maintenance: lots of entries
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