Hashsync – Deduplicate SSH streams against the receiver's files
Comments on “Hashsync – Deduplicate SSH streams against the receiver's files”
Claim-checked. Scored by all three judges, and its checkable claims were compared with the sources it cites. How far stories are checked
hashsync is an SSH wrapper that deduplicates the data streamed between two hosts against files the receiving host already holds. It finds matching 16 KiB blocks at any offset and sends references in their place, compressing what remains with zstd.
Why it ranked
No. 22 of 111 with a score of 0.61. The panel rated it highest on new information (0.93) and technical depth (0.88), lowest on audience breadth (0.42). Placed No. 22, No. 51 by score alone: the placement terms moved other stories past it.
- AI judgeJudge 2claude-haiku-5-5
- A new open-source tool with detailed technical design and benchmarks, practical for backup and transfer work, though a niche utility with self-reported measurements and limited broad significance.
- AI judgeJudge 3gpt-5.6-luna
- A technically detailed launch of a practical SSH stream deduplication tool, with protocol mechanics, security caveats, benchmarks, configuration, build instructions, and integrations. It is highly actionable for infrastructure and backup practitioners, though audience breadth is narrower than general tech.
Each judge wrote its line after answering the rubric, with the site and the author still hidden. Every answer behind this is in the table under Score.
Score
0.61total under rubric v2.3
- Significance0.49
- Reader interest0.69
- Audience breadth0.42
- Practical relevance0.74
- Substantiated0.79
- Technical depth0.88
- New information0.93
- Counts against: Promotional0.09
- Counts against: Overclaim0.12
Each judge’s answer per question (0–1), their mean and spread, and what the question adds to the score (weight × mean).
| Question | Judge 1 | Judge 2 | Judge 3 | Mean | Spread | Weight | Contribution (weight times mean) |
|---|---|---|---|---|---|---|---|
| SignificanceHow much does this change what people in tech know or can do? | 0.49 | 0.35 | 0.62 | 0.49 | 0.27 | +0.24 | +0.117 |
| Reader interestWould a well-informed senior engineer or tech founder want to read this today, and likely pass it on? | 0.58 | 0.60 | 0.90 | 0.69 | 0.32 | +0.26 | +0.180 |
| Audience breadthHow many people who build technology does it concern? | 0.44 | 0.40 | 0.42 | 0.42 | 0.04 | +0.13 | +0.055 |
| Practical relevanceHow useful is it to someone who builds software or tech products? | 0.77 | 0.60 | 0.84 | 0.74 | 0.24 | +0.22 | +0.162 |
| SubstantiatedHow well is it backed? Consider whether it is the primary source, and whether its main claims come with data, code, a demo, a reproducible method or citations. | 0.92 | 0.55 | 0.90 | 0.79 | 0.37 | +0.05 | +0.039 |
| Technical depthHow technically substantive is it? | 0.99 | 0.70 | 0.96 | 0.88 | 0.29 | +0.05 | +0.044 |
| New informationDoes it contain information absent from the stories covered in the last 7 days (list provided)? | 0.91 | 0.90 | 0.98 | 0.93 | 0.08 | +0.05 | +0.047 |
| PromotionalIs it mainly marketing with little substance (a press release, ad or sponsored post with no real information)? A launch post that carries real news is not promotional. | 0.07 | 0.15 | 0.04 | 0.09 | 0.11 | −0.19 | −0.016 |
| OverclaimDo the headline or conclusions claim more than the body supports? | 0.12 | 0.20 | 0.05 | 0.12 | 0.15 | −0.11 | −0.014 |
| Sum of contributions | +0.614 | ||||||
| Claim-check penalty | 0.000 | ||||||
| Total, as published | 0.614 | ||||||
Spread is the highest minus the lowest judge answer. marks a spread above 0.40: the judges disagree, and the story is marked contested.
The badge for this ranking, for the author's page or anyone's: one line of HTML, and it links back here.
<a href="https://rubric.hrih.si/editions/2026-10-31/22/"><img src="https://rubric.hrih.si/badge/2026-10-31/22.svg" alt="Ranked #22 on Rubric, 31 Oct 2026" width="245" height="28"></a>Claim check
Claim check: 7 no source given · 1 couldn’t check. Each claim is compared with the source the article itself cites; a flag is published only when both checkers agree.
No source givenBenchmark result
Over a 2 MiB/s link, copying the GPT-2 repository v2 took 19 minutes with rsync alone but only 4 minutes with hashsync.
The article gives no link or citation for it.
The article says “Over a 2 MiB/s link, the copy took 19 minutes with rsync alone but only 4 minutes with hashsync”
The source says No source to compare with.
No source givenNumber
In the example pull, hashsync reported a data shrinkage factor of 5.72 and saved 1.93 GiB of data transfer.
The article gives no link or citation for it.
The article says “data shrinkage factor: 5.72, saved 1.93 GiB of data transfer”
The source says No source to compare with.
No source givenDate
The benchmark used v1 and v2 of the GPT-2 repository on Hugging Face as of 2021-05-19 and 2024-02-19, with v2 adding a safetensors file and three ONNX files.
The article gives no link or citation for it.
The article says “v1 and v2 were the GPT-2 repository on Hugging Face as of 2021-05-19 and 2024-02-19; v2 adds a safetensors file and three ONNX files”
The source says No source to compare with.
No source givenCausal conclusion
rsync sends file data in pieces of at most 32 KiB, each preceded by its length, so with the default 16 KiB blocks hashsync can miss up to half of the blocks.
The article gives no link or citation for it.
The article says “hashsync can't match a block that one of these lengths splits, so with the default 16 KiB blocks, it can miss up to half of the blocks”
The source says No source to compare with.
Couldn’t checkVersion
The extras/rsync-3.5.1.patch raises rsync's data piece limit to 8 MiB.
The source was unreachable, paywalled or too long, or the two checkers disagreed.
The article says “extras/rsync-3.5.1.patch raises the limit to 8 MiB”
The source says No passage could be compared.
Source cited by the article: github.com/someplaceguy/hashsync/blob/master/extras/rsync-3.5.1.patch
No source givenVersion
hashsync runs on Linux 5.8 or later and must be installed on both hosts.
The article gives no link or citation for it.
The article says “hashsync runs on Linux 5.8 or later, and needs to be installed on both hosts”
The source says No source to compare with.
No source givenGeneralization
Because the receiver verifies block references with a strong cryptographic hash, an outdated index or concurrent file change only reduces deduplication and the output always matches the original stream byte for byte.
The article gives no link or citation for it.
The article says “if the index is outdated or a file is changed concurrently, this only results in less deduplication: the output always matches the original stream byte for byte”
The source says No source to compare with.
No source givenNumber
hashsync compresses non-deduplicated data with zstd by default at level 9, with long-distance matching and one thread per core.
The article gives no link or citation for it.
The article says “by default at level 9, with long-distance matching and one thread per core”
The source says No source to compare with.
Also covered by
No other coverage was clustered with this story.
Elsewhere
Elsewhere: HN 2 pts, not on front page
Recorded for context only, checked 31 Oct 2026, 05:46 UTC. It played no part in the ranking.