rqlite VS fuse

Seems like you could do the same with rqlite [1], since SQLite supports JSON.

[1]: https://rqlite.io

rqlite[1] creator here, happy to answer any questions about rqlite, this latest release, and how it works.

[1] https://rqlite.io

I found simple distributed RQlite https://github.com/rqlite/rqlite based on raft and sqlite. How hard is to add it?

rqlite[1] creator here, happy to answer any questions. rqlite also supports read-only nodes, which can also help with reads at the "edge". It probably wouldn't scale to 100s of nodes, it is an option.

"rqlite supports adding read-only nodes. You can use this feature to add read scalability to the cluster if you need a high volume of reads, or want to distribute copies of the data nearer to clients – but don’t want those nodes counted towards the quorum. These types of nodes are also known as non-voting nodes."

[1] https://rqlite.io/

[2] https://rqlite.io/docs/clustering/read-only-nodes/

For this first implementation I used Go. After a reviewing some solutions I decided to use https://github.com/bazil/fuse. It seemed to be the easiest way to prototype.

Often, the SQLite database would fit in RAM, and reads would be served straight from the page cache, with no overhead.

Disclaimer: I wrote the FUSE framework LiteFS uses, https://bazil.org/fuse -- and I also have some pending performance-related work to finish, there...

I'd love to upgrade but I rely on mounting my Google Drive via /dev/fuse and rclone. There was a post yesterday saying that is broken in 13.1-RELEASE and linking to a FreeBSD bug which links to a rclone bug which links to a bazil bug which seems to have no traction. Someone mentioned a commandline utility that can interact with gdrive but this seems like a pretty bad replacement. IIUC the FreeBSD devs' theory is that a new async system call path exposed a bug in rclone and the blame is there. Anyway, I'm still on 13.0 for now, unfortunately.

This was also reported to rclone where someone pointed out that the problem is with fuse lib on FreeBSD and as such is a FreeBSD fuse lib porting problem.

> 'failed' state and the process itself leaving the accounting tables.

Once again, that cannot be done until the parent process consumes the exit status. That's what the zombie is there for. Zombies don't take up much space.

> Stuck mounts have a half solution (lazy unmounts) but even _that_ interface really also needs a timeout value after which operations on the target should be assumed to fail rather than return correctly.

These days most NFS etc mounts are "soft mounts", that is operations will eventually time out.

Lazy unmount doesn't really apply here, it makes the mountpoint disappear from the global namespace, but all existing open files remain untouched, and the mount lives as long as anything is still using it; it just removes the "entry point" to the mount.

On today's Linux, it's up to each filesystem to provide abort/timeout mechanism. For timeouts, this is the right design, as demonstrated by macOS complications with FUSE. I do wish there was a common way to make things abort.

There was a patch in circulation a long time ago, that could seamlessly switch all open FDs of any given mountpoint into a whole different filesystem named badfs. badfs would just return an error on any operation. As far as I know, that patch never got merged, probably because nobody ever got it working 100%.

That kind of a DoS would require a local attacker, and then the victim to access a mountpoint owned by the attacker. Using FUSE, you could get a lot of processes hanging like that, for sure. I guess you could trap a mail delivery agent, if you still had a system where mail was delivered to users' home directories.

However, forcibly aborting any FUSE mount is a single `echo 1 >/sys/fs/fuse/connection/NNNN/abort`, the only challenge is finding the right ID. (See https://github.com/bazil/fuse/blob/fb710f7dfd05053a3bc9516dd...)