Changes between Version 83 and Version 84 of FAQ


Ignore:
Timestamp:
2013-01-28T22:42:18Z (11 years ago)
Author:
zooko
Comment:

added Q15.1 dedupe dangers

Legend:

Unmodified
Added
Removed
Modified
  • FAQ

    v83 v84  
    110110'''[=#Q15_same_file_same_cap Q15:] If upload the same file again and again, Tahoe-LAFS will return the same capability. How does Tahoe-LAFS identify that the client is same, when I upload files mutiple times, is it based on node ID?'''
    111111
    112 A: For immutable files this is true—the resulting capability will be the same each time you upload the same file contents.  The capability is derived from two pieces of information:  The content of the file and the "convergence secret".  By default, the convergence secret is randomly generated by the node when it first starts up, then stored and re-used after that.  So the same file content uploaded from the same node will always have the same cap string.  Uploading the file from a different node with a different convergence secret would result in a different cap string—and in a second copy of the file's contents stored on the grid. If you want files you upload to converge (also known as "deduplicate") with files uploaded by someone else, just make sure you're using the same convergence secret as they are.
     112A: For immutable files this is true—the resulting capability will be the same each time you upload the same file contents.  The capability is derived from two pieces of information:  The content of the file and the "convergence secret". By default, the convergence secret is randomly generated by the node when it first starts up, then stored in the node's base directory ({{{~/.tahoe}}}) and re-used after that. So the same file content uploaded from the same node will always have the same cap string. Uploading the file from a different node with a different convergence secret would result in a different cap string—and in a second copy of the file's contents stored on the grid. If you want files you upload to converge (also known as "deduplicate") with files uploaded by someone else, just make sure you're using the same convergence secret as they are.
     113
     114'''[=#Q15.1_dedupe_dangers Q15.1:] Isn't deduplication dangerous? Can someone figure out whether or not I have a certain file?'''
     115
     116A: to be added
    113117
    114118'''[=#Q16_move_node_to_different_machine Q16:] If I move the client node base directory to different machine and start the client there, will the node have the same node ID as on the previous machine?'''