By default, you get snapshots every minute for the last hour, every hour for the last day, and every day into perpetuity. This is configurable. You can set as many cadences as you wish, with the ability to configure their frequency and lifetimes.
Actually, snapshots are like btrfs volumes in many ways, meaning they can be mounted, read from, and written to as desired. This allows the filesystem root to just be another snapshot with a default backup cadence as described above.
The gefs(4) manpage [0] has more info for those interested. It's a short and sweet read. The source [1], is under 12k lines of well-written code, comments and whitespace included. The author is also extremely responsive to issues and a pleasure to talk shop with.
Anyway, given the parsimony of the OS and the small community size, I find 9front to be a really nice incubator for playing around with new ideas.
[0]:https://man.9front.org/4/gefs [1]:https://git.9front.org/plan9front/9front/front/sys/src/cmd/g...
We need more of this type of project today. It is the old Internet, still alive.
It is possible to assert the point is to identify outsiders. Or exclude. Or test to find insiders, to welcome people who chose to align, or not.
I never invested enough to feel I'd even knocked on the door, let alone incanted a phrase to be let in. However I have known IRL and online many who did and they aren't bad people. Or even really exclusive or excluding. They just have a culture. And if it excludes the dismal or the misaligned or the fame seekers and hangers on, that's probably not just a side effect.
Compsci is littered with ingroups and outsiders. The people who get invited to Tannenbaums workshops. The people who got invited once and never again. The people who don't get invites. This is normal. Not everyone gets invited to join the royal society and not everyone wants to.
Some people assert its an intelligence test but I remain a fan of the aphorism from "war games" - the only winning move is not to play.
But, I don't think the Plan 9 team ever figured out how to elegantly implement security/isolation-related primitives like secret storage with a single general mechanism. Their "canonical" way of providing secure authentication relies on a few ad-hoc capability mechanisms, built on top of 9P deeply integrated with some special-purpose kernel features. [1] If Bell Labs had more time, I think they would've ended up rethinking 9P around this issue.
[1] https://css.csail.mit.edu/6.858/2013/readings/plan9auth.pdf
I still would like to make a server with it though. Maybe that would be a good weekend project.
EDIT: website is just an inside joke and not helpful. OS is real but also not helpful. https://www.reddit.com/r/plan9/comments/1mr6cyr/comment/n8xp...
EDIT: I think some of the in-jokey, arty farty culture about it is because the rest of us didn't run with it, it's basically for hobby and personal use - so its culture now. But about any one I know who has used it enough to "grok" it kinda is like "wow if this won" because its kinda such a paradigmatically good thing whole kind of cottage industries of software may not even exist because the user would be able to write a pipe from a file that is a device to write to another one type thing.