Arch Linux

dcraig327

Member

Registered: 2021-01-27

Posts: 6

Arch on a rw tmpfs and also write to disk

Hi.
Thanks for your time.

I've a question how to load an entire fs with Arch installed on it, into RAM, but also allowing writes to a NVMe array. I've heard this was done before, but not sure if done recently. The only package I've seen that supports that doesn't support kernel 5.10+
https://en.wikipedia.org/wiki/List_of_L … n_from_RAM
https://github.com/arcmags/ramroot

I understand the risks of losing un-written data or possibly corrupting the fs if the writes aren't completed, going to setup a UPS with adequate time to flush the buffer during power loss. I imagine this would increase CPU usage a bit. The goal is to increase throughput and reduce latency when accessing files on disk. Even if it's no longer possible to do this for the kernel or for all Arch files, I would be interested in how to do this for my user's files & VM's. I'm sure there's lots on my plate to read and I'd love some pointers. Do you have any ideas or pointers on where I should start?

What I know & found out:

• I don't understand when or which files the kernel caches to RAM, or all writes it does to disk (ie: non-user requested writes).

• I sort-of get how to use tmpfs, but not how it works behind the scenes or how to put an entire fs into RAM during, say, initrd/initramfs.

• I heard someone say they could copy contents of a tmpfs to a disk using rclone .. which sounds like an awesome idea.

• I've used rclone a bit and have some scripts to automate it via cron.

Would rclone work? Any better solutions?

opensorcerer

Member

From: Germany

Registered: 2021-06-05

Posts: 14

Re: Arch on a rw tmpfs and also write to disk

This, probably: https://unix.stackexchange.com/question … x-from-ram.
If you only want programs to be quickly launched, see https://wiki.archlinux.org/title/Preload.
In general, there should be very little difference between starting from RAM and starting from a NVMe SSD. Maybe the latter is best suited for what you want to achieve?

Take care and good luck!

damjan

Member

Registered: 2006-05-30

Posts: 462

Re: Arch on a rw tmpfs and also write to disk

Hi.

What I know & found out:

• I don't understand when or which files the kernel caches to RAM, or all writes it does to disk (ie: non-user requested writes).

The kernel caches everything by itself, and is quite smart about it. Generally you shouldn't try to outsmart it