Difference between revisions of "User:StefanoZacchiroli/Content deduplication"
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Some experiments on deduplicating contents at sub-file granularity. | Some experiments on deduplicating contents at sub-file granularity. | ||
| − | == Linux kernel, Git repo == | + | == Datasets == |
| + | |||
| + | === Linux kernel, Git repo === | ||
* origin: git.kernel.org, on 2018-01-06 | * origin: git.kernel.org, on 2018-01-06 | ||
* 1.653.941 content blobs, for a total of 19 GB (compressed) | * 1.653.941 content blobs, for a total of 19 GB (compressed) | ||
| + | * original size (uncompressed): '''55.89 GB''' | ||
| + | |||
| + | === Random sample 0.1% === | ||
| + | |||
| + | * random 0.1% Bernoulli sample of Software Heritage contents, took on 2018-01-09 | ||
| + | * 4.111.582 contents blobs, for a total of 155 GB (compressed) | ||
| + | * original size (uncompressed): '''286.99 GB''' | ||
| − | == Rabin | + | == Rabin fingerprint chunking == |
| − | + | * Approach: use [https://en.wikipedia.org/wiki/Rabin_fingerprint Rabin fingerprints] as in LBFS | |
| + | * Implementation: [https://forge.softwareheritage.org/source/snippets/browse/master/zack/swh-dedup/ swh-dedup-blocks.py] | ||
=== test 1 === | === test 1 === | ||
| + | |||
| + | Dataset: linux.git | ||
| + | |||
| + | Rabin fingerprint parameters: | ||
| + | * prime: 3 | ||
| + | * window_size: 48 | ||
| + | * chunk size (min/avg/max): 2 KB / 8 KB / 64 KB | ||
| + | |||
| + | Results: | ||
| + | * average chunk size (effective): 9.37 KB | ||
| + | * dedup chunk size (uncompressed): '''19.87 GB (35.55%)''' | ||
| + | |||
| + | === test 2 === | ||
| + | |||
| + | Dataset: linux.git | ||
| + | |||
| + | Rabin fingerprint parameters: | ||
| + | * prime: 3 | ||
| + | * window_size: 48 | ||
| + | * chunk size (min/avg/max): 512 B / 2 KB / 8 KB | ||
| + | |||
| + | Results: | ||
| + | * average chunk size (effective): 2.86 KB | ||
| + | * dedup chunk size (uncompressed): '''9.09 GB (16.26%)''' | ||
| + | |||
| + | === test 3 === | ||
| + | |||
| + | Dataset: linux.git | ||
| + | |||
| + | Rabin fingerprint parameters: | ||
| + | * prime: 3 | ||
| + | * window_size: 48 | ||
| + | * chunk size (min/avg/max): 512 B / 1 KB / 8 KB | ||
| + | |||
| + | Results: | ||
| + | * average chunk size (effective): 1.72 KB | ||
| + | * dedup chunk size (uncompressed): '''6.49 GB (11.60%)''' | ||
| + | |||
| + | === test 4 === | ||
| + | |||
| + | Dataset: random sample 0.1% | ||
Rabin fingerprint parameters: | Rabin fingerprint parameters: | ||
* prime: 3 | * prime: 3 | ||
| − | * window_size: 48 | + | * window_size: 48 |
| − | * | + | * chunk size (min/avg/max): 512 B / 1 KB / 8 KB |
| − | |||
| − | |||
Results: | Results: | ||
| − | * | + | * average chunk size (effective): 1.56 KB |
| − | * dedup chunk size (uncompressed): | + | * dedup chunk size (uncompressed): '''244.09 GB (85.05%)''' |
== References == | == References == | ||
| Line 29: | Line 78: | ||
* [https://pdfs.semanticscholar.org/5231/82a9a66f96241d4bab0b92cc92e9cbda22c7.pdf DCT] | * [https://pdfs.semanticscholar.org/5231/82a9a66f96241d4bab0b92cc92e9cbda22c7.pdf DCT] | ||
* [https://github.com/nexB/scancode-toolkit/blob/ba5be09e54f57bd519239fd81746ebc4d0f9af9c/src/licensedcode/tokenize.py#L188 ScanCode tokenizer] | * [https://github.com/nexB/scancode-toolkit/blob/ba5be09e54f57bd519239fd81746ebc4d0f9af9c/src/licensedcode/tokenize.py#L188 ScanCode tokenizer] | ||
| + | * [https://moinakg.wordpress.com/2013/06/22/high-performance-content-defined-chunking/ Pcompres chunking] (linked from [http://0pointer.net/blog/casync-a-tool-for-distributing-file-system-images.html casync]) | ||
Latest revision as of 14:32, 4 May 2018
Some experiments on deduplicating contents at sub-file granularity.
Datasets
Linux kernel, Git repo
- origin: git.kernel.org, on 2018-01-06
- 1.653.941 content blobs, for a total of 19 GB (compressed)
- original size (uncompressed): 55.89 GB
Random sample 0.1%
- random 0.1% Bernoulli sample of Software Heritage contents, took on 2018-01-09
- 4.111.582 contents blobs, for a total of 155 GB (compressed)
- original size (uncompressed): 286.99 GB
Rabin fingerprint chunking
- Approach: use Rabin fingerprints as in LBFS
- Implementation: swh-dedup-blocks.py
test 1
Dataset: linux.git
Rabin fingerprint parameters:
- prime: 3
- window_size: 48
- chunk size (min/avg/max): 2 KB / 8 KB / 64 KB
Results:
- average chunk size (effective): 9.37 KB
- dedup chunk size (uncompressed): 19.87 GB (35.55%)
test 2
Dataset: linux.git
Rabin fingerprint parameters:
- prime: 3
- window_size: 48
- chunk size (min/avg/max): 512 B / 2 KB / 8 KB
Results:
- average chunk size (effective): 2.86 KB
- dedup chunk size (uncompressed): 9.09 GB (16.26%)
test 3
Dataset: linux.git
Rabin fingerprint parameters:
- prime: 3
- window_size: 48
- chunk size (min/avg/max): 512 B / 1 KB / 8 KB
Results:
- average chunk size (effective): 1.72 KB
- dedup chunk size (uncompressed): 6.49 GB (11.60%)
test 4
Dataset: random sample 0.1%
Rabin fingerprint parameters:
- prime: 3
- window_size: 48
- chunk size (min/avg/max): 512 B / 1 KB / 8 KB
Results:
- average chunk size (effective): 1.56 KB
- dedup chunk size (uncompressed): 244.09 GB (85.05%)
References
- LBFS
- Hailstorm
- DCT
- ScanCode tokenizer
- Pcompres chunking (linked from casync)