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Comment by kristopolous | Hacker News Reader

> Swap is still actively harmful if placed on an unsuitable device.

Reading that, I just realized it could be done over the network - that would be impressively glacial. Should be a good laugh.

Heck, why not over a db9 null modem slip connection? Start a compile and send it off to the Long Now Foundation - set it up next to John Cage's ASLSP organ.

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You can laugh - and maybe should laugh - but this is in fact a real thing. Swapping to NFS was... I won't say common, but not unheard of once upon a time, almost always in diskless machines. You boot from the network, you mount your root filesystem and home over the network, you swap over the network. These days it's better to use NBD (network block device) for that, at least on Linux, but the option remains. And yes, it remains a pretty niche thing, because yeah network isn't exactly ideal performance, but it's available if you need it.

IIRC nbd even explicitly supports being used as swap device (swap on some generic network FS is a bad idea because it is essentially guaranteed to deadlock the VM subsystem) and I have seen it used that way for disk-less workstations in early 00's.

That's the vision of CXL :-) To be fair, the network is very very fast.

https://en.wikipedia.org/wiki/Compute_Express_Link

Oh this is a special cluster interconnect.

Yes, those have always been impressive and usually cost as much as a luxury sports car.

Hopefully the increased demand from the AI world will help bring those prices down.

infiniband is pretty cheap now!

Apps would crash before the device got the traffic back telling it what to swap out.

swap would be fast enough on NVMe-oF for anything not a DB, no?

I'd imagine latency matters more than throughout. Complicated disk operations over my 10Gb fiber network still sucks like it did over 10baseT 30 years ago. Maybe there's smarter ways to set things up but NFS/sshfs is still bogged down for me. 1/5th - ~1/100th depending on the application.

Also I don't have fancy money. I was imagining the $20 gear on Amazon/eBay. Maybe that's my problem...

Oh, I've meant putting NVMe proto on a wire, with such drives on the other side. Not traditional network app protocols.

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