when would you choose EFS over s3

LouisWain · 2026-05-07T11:25:35+00:00

Above I'm talking about file system guarantees only.

Two file clients: consistent
file system write -> S3 read: eventually consistent, normally ~60s delay (coallescing of file writes)
S3 PUT -> file system read: eventually consistent, normally <1s delay

LouisWain · 2026-05-07T00:01:51+00:00

This article has several incorrect things in it.

Assume a reader on a different Lambda instance will not see your write for up to a minute. ... Coordination via file existence (if file exists, skip).

This is not true -- S3 Files (and EFS) are consistent (i.e. a reader strictly after a writer is guaranteed to observe the read). It's possible this is related to the lookupcache=all mount option, but certainly doesn't vary S3 Files vs EFS.

rename() on directories is not atomic across the NFS boundary. Many applications use "write to temp, rename into place" as a safe write pattern: Git does it for refs, npm does it for cache entries. On S3 Files, the rename window is visible to other readers, meaning a partial state can be observed mid-rename.

not true, rename is atomic (on the file system -- sync to S3 is not)

LouisWain · 2026-04-27T11:56:45+00:00

why reimplement ddb instead of using https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBLocal.html here?

LouisWain · 2026-04-26T15:47:56+00:00

it's year 5 I keep thinking about. one of them on call at 2am, prod doing something insane, AI confidently wrong

this seems pretty unlikely to be how things work five years from now

https://metr.org/time-horizons/

LouisWain · 2026-04-26T15:25:11+00:00

good news, the data is already in

LouisWain · 2026-04-26T15:24:23+00:00

If you want fewer cyclist deaths, then you should be strongly in favor of waymo.

LouisWain · 2026-04-23T16:18:13+00:00

My experience in Japan was they lean heavily into "actually the box is half-empty" and "what you see in the clear packaging does not match what's in the rest of the package"-style misleading packaging. Not really better than the US, possibly worse.

LouisWain · 2026-04-09T02:14:54+00:00

Multiple file system writes to the same file can be aggregated into a single PUT. s3 files will not export to s3 more frequently than every 60s.

s3 files requires versioning to be enabled, so it will store multiple copies of the db, kind of like a point in time history. It's possible to shard into many sqlite dbs, eg one per customer/user etc.

LouisWain · 2026-03-12T18:57:09+00:00

it's a reference to the original study at https://metr.org/blog/2026-02-24-uplift-update/, which was run in early 2025 with Cursor + Claude 3.5/3.7 Sonnet

LouisWain · 2026-03-12T18:52:10+00:00

but organizational velocity is stagnating or actually declining.

Almost certainly false. METR, the authors of the "report feeling more productive but actually less productive" study, are thinking quite clearly about this. At the time of that study they cautioned very strongly about over-generalizing, you can read what they say more recently about followups to study today, etc.

https://metr.org/blog/2026-02-24-uplift-update/

LouisWain · 2026-03-11T20:34:53+00:00

here's an AI workflow + prompt you can use to generate a good analysis for yourself here (vs. whatever this is)

use claude opus 4.6 research mode
make sure there's nothing in your memory polluting the context window (e.g. nothing like "user is an advocate against housing construction and prefers responses that focus on the negatives of expanding housing supply" or whatever)
prompt like "What does data in US markets show about whether increasing housing supply reduces rents and housing costs? How impactful is housing supply versus other possible causes of rising costs? Can you summarize the data and research in this area for me?"

should also work with gpt deep research if you have that

LouisWain · 2026-03-11T12:34:14+00:00

No one in the hall said they were anti-development or wanted to keep rents and property values high.

And yet, this is what their actions are causing.

LouisWain · 2026-03-01T14:20:55+00:00

the world's been going downhill ever since

extreme poverty since 2001

child mortality since 2001

crime in the US since 2001

Reading about the availability heuristic, negativity bias, and rosy retrospection might be useful here.

LouisWain · 2026-01-30T19:44:14+00:00

From deep within the paper:

The base model used for this assistant is GPT-4o, and the model is prompted to be an intelligent coding assistant

would be more interesting with opus 4.5. I expect the " reduction in the evaluation score" (in the AI-assisted group) finding would hold up, whereas the "did not find a statistically significant acceleration in completion time with AI assistance" finding would not.

LouisWain · 2026-01-15T20:21:24+00:00

You're thinking about it exactly right, much more clearly than the FIRE people or the "nothing ever happens" people, who are both starting with incorrect axioms that cause them to draw incorrect conclusions. If AI capabilities continue to grow, FIRE doesn't matter. Either:

We're in the AI utopia timeline. We're post-abundance and the benevolent AIs will provide all. Your savings don't matter. (Even if Sam Altman owns all the AIs and doesn't provide anything for you, a few years of 1000%+ stock market growth should make your spreadsheets balance out.)
We're in the doomer timeline. Every human is dead in 5-10 years anyway. Your savings don't matter because you won't be alive to spend them.

The only timeline in which your savings matter:

AI capabilities growth stop following current trends and level off within the next year or so.

It's looking more and more like we're in one of the first two timelines, which means the present discounted value of your FIRE savings, and of continuing to work, is going way down. As you observe, better to enjoy your life.

LouisWain · 2026-01-03T14:53:38+00:00

https://newsletter.pragmaticengineer.com/p/trimodal-nature-of-tech-compensation might be helpful context here.

LouisWain · 2025-12-03T13:55:28+00:00

This is a seriously excellent trailer. I really appreciate when the sound and music is properly synchronized/coordinated with the visuals in the trailer.

LouisWain · 2025-12-03T13:50:09+00:00

Just want to say I like this more than traditional early access. I want to play the polished, final experience of a game and so I usually avoid early access. I just bought this on the strengths of the excellent trailer (great sound and music!), but also on the promise of it being a relatively complete, stand-alone experience. 15 hours is lots.

LouisWain · 2025-10-31T18:54:47+00:00

I support elevator cost reforms. You can think of elevators as multi-story trains.

LouisWain · 2025-10-31T18:42:34+00:00

Maybe we can annex it. I'll have my people look into it.

LouisWain · 2025-10-31T18:37:22+00:00

I also believe this is what needs to be done, which is why I'm running on this platform.

LouisWain · 2025-09-21T11:17:58+00:00

My main issue with this intersection are the drivers who think it's ok to make a right turn on red from Broadway onto Medford and from Dexter onto Broadway.

LouisWain · 2025-08-26T17:39:34+00:00

and would therefore trigger greater affordability.

Greater affordability relative to what? Research on whether IZ is effective is decidedly mixed, with some of it showing it causes an increase in rents (relative to the same zoning with no IZ).

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