GNU Coreutils 9.0: cp Now Enables CoW By Default + Copy Offload, wc Now Uses AVX2

[phoronix]

Phoronix: GNU Coreutils 9.0: cp Now Enables CoW By Default + Copy Offload, wc Now Uses AVX2

Coreutils 9.0 is now available and it's a significant update to this collection of common open-source utilities found on effectively all Linux systems...

https://www.phoronix.com/scan.php?page=news_item&px=GNU-Coreutils-9.0

[mystiquewolf]

I bet it wouldn't get into Kubuntu 21.10, would it?

[uid313]

GNU Coreutils are great, I don't know why my Ubuntu version of netcat is the OpenBSD version which sucks, it only has short options not long options.

[pipe13]

"cp now enables copy-on-write (CoW) support by default..."

What means this? I mean, these gnus ain't stupid and don't go around gratuitously breaking things. So what happens e.g. when rsnapshot uses cp to backup files from one file system to another? And what does sync do?

[cthart]

Copy on write requires filesystem support. But if the filesystem supports it, the copy will essentially be metadata only and only changed blocks will be stored if either copy gets modified.

[sinepgib]

[common open-source utilities found on effectively all Linux systems...

Not really all of them. In embedded and not-quite-embedded it's common to just use busybox, for example.

[pal666]

What means this?

in some circumstances it will be much faster

I mean, these gnus ain't stupid and don't go around gratuitously breaking things.

of course not

So what happens e.g. when rsnapshot uses cp to backup files from one file system to another?

same as before

And what does sync do?

what sync?

[Delgarde]

What means this? I mean, these gnus ain't stupid and don't go around gratuitously breaking things. So what happens e.g. when rsnapshot uses cp to backup files from one file system to another? And what does sync do?

If you're copying between filesystems, it means absolutely nothing. But if you're copying a file within a filesystem and that filesystem supports copy-on-write, then the copy is essentially just a pointer to the same disk as the original — until either of the copies is modified, at which point the filesystem needs to deal with it. So as long as the copies remain identical, you're not using any extra space by having them.

[Rallos Zek]

GNU Coreutils are great, I don't know why my Ubuntu version of the OpenBSD version of netcat which sucks, it only has short options not long options.

Netcat is not a part of Coreutils, and iirc most of the major implementations of netcat have not been updated in 10 years or more since Netcat is relatively stable.

[Gonk]

But if you're copying a file within a filesystem and that filesystem supports copy-on-write, then the copy is essentially just a pointer to the same disk as the original — until either of the copies is modified, at which point the filesystem needs to deal with it. So as long as the copies remain identical, you're not using any extra space by having them.

So basically - for lack of a better term - preemptive dedup.