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One of the things that surprised me following last week's Jepsen report on Radix DLT (jepsen.io/analyses/radix-dlt-1) was seeing both blockchain/DLT people *and* the database community go "Hang on, 16 transactions per second can't be right"--and expecting wildly different figures.

Also, like... if y'all have questions about these results, ask! Here to help.

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#8 wasn't easy to find in the first place, which means it's hard to be *super* confident in it being fixed without a clear explanation for its cause. BDB durability might have been related, but sometimes errors like this are just masked, rather than fixed, by timing changes.

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Transaction loss in the underlying ledger system was definitely caused by github.com/radixdlt/radixdlt/c: basically the core ledger opted not to wait for data to be flushed to disk before saying "Got it!". We never figured out #8, but I wasn't able to reproduce it in 655dad3.

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Ah--a small clarification here! We found two issues in the raw Radix DLT ledger API. #8 involved transactions appearing in the raw txn log, then being immediately replaced by different txns. #10 involved nodes confirming then forgetting txns when many nodes crashed at once.
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RT @rad_guild
@JackRNewhouse @a_vaunt The transaction logging was problematic but the actual ledger was and is fine AFAICT.
twitter.com/rad_guild/status/1

For Radix DLT folks concerned about 16 vs. 50 transactions per second--I wouldn't worry about that at all. In benchmark terms those are basically the same number. As mentioned in the report, we're talking about different hardware, a different network, and different workloads. :-)

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RDX Works (the makers of Radix DLT) states that all safety issues as well as the problem with indefinite transactions have been resolved as of Radix DLT 1.1.0.

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Jepsen's latest distributed systems safety report covers Radix DLT 1.0-beta.35.1 through 1.0.2. We found stale, aborted, and intermediate reads, as well as the partial or total loss of committed transactions. Transactions could also hang indefinitely.

jepsen.io/analyses/radix-dlt-1

If the idea of writing a page cache for a pathologically lazy filesystem that loses unsynced data on command sounds like fun, I'd like like to hear from you!

jepsen.io/filesystem

RT @asatarin
Great talk by @vanlightly @hydraconference

He compares modeling and verification of a simple distributed log with and @jepsen_io Maelstrom

- overview of both
- pros and cons of those approaches
- how to move from model to implementation

Jack covers a lot in the talk twitter.com/lemmster/status/14

If you hate databases and long load times, I've got great news. Jepsen 0.2.6 is now available, and includes a new binary file format which makes working with test data much faster. github.com/jepsen-io/jepsen/re

RT @pfeodrippe
Hi, released a overhauled version of Recife, now using TLC :)

- Use Clojure and the REPL;
- Visualize the trace:
- Hillel's examples from his book:
- Also an example using @jepsen_io's Elle lib.

Made a small video about it at
youtu.be/C9WwF4RXq74.

github.com/pfeodrippe/recife

A small change to the ethics policy (jepsen.io/ethics): for environmental reasons, Jepsen no longer performs analyses of proof-of-work or proof-of-space systems.

Jepsen 0.2.4 is now available. New SSH backend options, performance improvements, and a local filesystem cache to speed up DB setup. Happy testing! github.com/jepsen-io/jepsen/re

scattered-thoughts.net/writing

"We might get outputs that are arbitrarily wrong, up to and including breaking program invariants"

"The outputs might never converge to correctness"

Giving a short talk on Jepsen at LADIS this afternoon! Our session starts at 14:45 US Eastern. ladisworkshop.org/2021/

Live stream:
youtube.com/watch?v=0cfJNFt1bW

New release! Maelstrom 0.2.0 is a workbench for learning distributed systems by writing your own, in any language. Comes with a six-chapter tutorial in writing your own toy echo, gossip, CRDT, Datomic, and Raft systems. Powered by Jepsen and Elle! github.com/jepsen-io/maelstrom

New Jepsen release: 0.2.3. Super small, just a few bugfixes and performance improvements. Enjoy! github.com/jepsen-io/jepsen/re

Howdy guys, gals, and non-binary pals! Jepsen 0.2.2 is now available, with a slew of minor bugfixes, performance improvements, and new utility functions. Look out for a change to multi-fault nemesis scheduling: github.com/jepsen-io/jepsen/re

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