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nncp-reass

$ nncp-reass [options] [-dryrun] [-keep] [-dump] [-stdout] FILE.nncp.meta
$ nncp-reass [options] [-dryrun] [-keep] {-all | -node NODE}

Reassemble chunked file after tossing.

When called with FILE option, this command will reassemble only it. When called with -node option, this command will try to reassemble all .nncp.meta files found in NODE’s incoming directory. When called with -all option, then cycle through all known nodes to do the same.

Reassembling process does the following:

  1. Parses .nncp.meta file.
  2. Checks existence and size of every .nncp.chunkXXX.
  3. Verifies integrity of every chunk.
  4. Concatenates all chunks, simultaneously removing them from filesystem.

That process reads the whole data twice. Be sure to have free disk space for at least one chunk. Decrypted chunk files as a rule are saved in pseudo-random order, so removing them during reassembly process will likely lead to filesystem fragmentation. Reassembly process on filesystems with deduplication capability should be rather lightweight.

If -dryrun option is specified, then only existence and integrity checking are performed.

If -keep option is specified, then no .nncp.meta/.nncp.chunkXXX files are deleted during reassembly process.

-stdout option outputs reassembled file to stdout, instead of saving to temporary file with renaming after. This could be useful for reassembling on separate filesystem to lower fragmentation effect, and/or separate storage device for higher performance.

-dump option prints meta-file contents in human-friendly form. It is useful mainly for debugging purposes. For example:

Original filename: testfile
File size: 3.8 MiB (3987795 bytes)
Chunk size: 1.0 MiB (1048576 bytes)
Number of chunks: 4
Checksums:
    0: eac60d819edf40b8ecdacd0b9a5a8c62de2d15eef3c8ca719eafa0be9b894017
    1: 013a07e659f2e353d0e4339c3375c96c7fffaa2fa00875635f440bbc4631052a
    2: f4f883975a663f2252328707a30e71b2678f933b2f3103db8475b03293e4316e
    3: 0e9e229501bf0ca42d4aa07393d19406d40b179f3922a3986ef12b41019b45a3

Do not forget about possible ZFS deduplication issues.


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