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Linus: Don't Use ZFS

realworldtech.com

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Re: Linus: Don't Use ZFS

#101

Earlier quoted context omitted.

For what? It's under the CDDL.

API Infringement.

That's not even a thing (yet).

ZFS was freely relicensed under the CDDL by Sun. Oracle can do nothing to take back any of the rights granted under the terms of the licence retrospectively. They haven't got any grounds whatsoever to curtail anyone's use or modification of the ZFS code.

Re: Linus: Don't Use ZFS

#102

"Don't use ZFS. It's that simple. It was always more of a buzzword than anything else, I feel, and the licensing issues just make it a non-starter for me." - Linus I have a strong feeling Linus has never actually used ZFS.

I once read this story about the problems trying to support ZFS - was it in the Linux kernel, though? Can't remember. Sadly, I can't seem to be able to dig it up right now, but the article walking readers through the various clashes in constraints between the different systems and implementations was bordering on the humourous.

Re: Linus: Don't Use ZFS

#103
post #91
post #28

Earlier quoted context omitted.

I agree that ZFS has a lot to offer. But the legal difficulties in merging ZFS support into the mainline kernal are understandable. It's a shame but I think he is making the right call.

Merging into the mainline kernel is not what the person he is replying to was even asking for. All they were asking is for Linux to stop putting APIs behind DRM that prevents non-GPL modules like ZFS from using them. That doesn't mean ZFS must be bundled with Linux. I think everyone is in agreement that ZFS can't be included in the mainline kernel. The question is just if users should be able to install and use it th…

Thanks, I should have read more into this.

The follow up actually clears things up pretty well. https://www.realworldtech.com/forum/?threadid=189711&curpost...

Re: Linus: Don't Use ZFS

#104

Earlier quoted context omitted.

I am also not an expert in this space - but if I understand correctly the reason the linux Nvidia driver sucks so much is that it is not GPL'd (or open source at all). There is little incentive for Nvidia to maintain a linux specific driver, but because it is closed source the community cannot improve/fix it. > Why are all drivers expected to use the GPL? I think the answer to this is: drivers are expect to use the G…

I would expect a large fraction of Nvidia's GPU sales to be from customers wanting to do machine learning. What platform do these customers typically use? Windows? How do the Linux and Windows drivers compare on matters related to CUDA?

Nvidia has a proprietary Linux driver that works just fine for GPGPU purposes. But because it's not GPLed, it will never be mainlined into the kernel, so you have to install it separately. This is in contrast to AMD GPUs, for which the driver lives in the Linux kernel itself.

Re: Linus: Don't Use ZFS

#105
post #25

As a heavy user of ZFS and Linux, what else is there that even comes close to what ZFS offers? I want cheap and reliable snapshots, export & import of file systems like ZFS datasets, simple compression, caching facilities(like SLOG and ARC) and decent performance.

Bcachefs is probably the only thing that will get there. The codebase is clean and we'll mantained, built from solid technology (bcache) and will include most of the ZFS niceties. I just wish more companies would sponsor de project and stop wasting money on BTRFS

What if the main purpose of BTRFS is to have something "good enough" so no one starts working on a project that can compete with large commercial storage offerings?

Does anyone remember the parity patches they rejected in 2014?

> Your work is very very good, it just doesn’t fit our business case.

I haven't followed it much. Does it have anything more than mirroring (that's stable) these days?

Re: Linus: Don't Use ZFS

#106

Earlier quoted context omitted.

He also feels ZFS "was always more of a buzzword than anything else". Yikes.

Honestly, I wouldn't bash him for this comment. Not everyone runs a 10+ TB array at their home for storage and backup purposes. ZFS doesn't primarily target single disks and small arrays anyway. :)

ZFS made wonders for me with very small servers (appliances) with SSDs that were forced to operate in remote areas on unstable power supply - where other file systems were dropping bytes and bricking them.

Re: Linus: Don't Use ZFS

#107
post #81
post #24

Earlier quoted context omitted.

Not sure where that belief comes from. But it might be that many benchmarks are naive and compare it against other filesystems in single-disc setups with zero tuning. Since its metadata overheads are higher, it's definitely slower in this scenario. However, put a pool onto an array of discs and tune it a little, and the performance scales up and up leaving all Linux-native filesystems, and LVM/dm/mdraid, well behind.…

Last time I used ZFS write performance was terrible compared to an ordinary RAID5. IIRC Writes in a raidz are always limited to a single disk’s performance. The only way to get better write speed is to combine multiple raidzs - which means you need a boatload if disks.

We had a bunch of Thumpers (SunFire X4200) with 48 disks at work, running ZFS on Solaris. It was dog slow and awful, tuning performance was complicated and took ages. One had to use just the right disks in just the right order in RaidZs with striping over them. Swap in a hotspare: things slow to a crawl (i.e. not even Gbit/s).

After EoL a colleague installed Linux with dmraid, LVM and xfs on the same hardware: much faster, more robust. Sorry, don't have numbers around anymore, stuff has been trashed since.

Oh, and btw., snapshots and larger numbers of filesystems (which Sun recommended instead of the missing Quota support) also slow things down to a crawl. ZFS is nice on paper and maybe nice to play with. Definitely simpler to use than anything else. But performance-wise it sucked big time, at least on Solaris.

Re: Linus: Don't Use ZFS

#108

Earlier quoted context omitted.

> If there is no "approved" method for creating Linux drivers under licenses other than the GPL, that seems like a major problem that Linux should be working to address. The problem is already addressed: if someone wants to contribute code to the project then it's licensing must be compatible with the prior work contributed to project. That's it.

But why are all drivers expected to be "part of the project"? We don't treat userspace Linux software that way. We don't consider Windows drivers part of Windows.

It's pretty simple, once they expose such an API they'd have to support it forever, hindering options for refactoring (that happens all the time). With all the drivers in the tree, they can simply update every driver at the same time to whatever new in-kernel API they're rolling out or removing. And being that the majority of drivers would arguably have to be GPL anyway, and thus open-source, the advantages of keeping all the drivers in tree are high, and the disadvantages low.

With that, they do expose a userspace filesystem driver interface, FUSE. There used to be a FUSE ZFS driver, though I believe it's mostly dead now (But I never used it, so I don't know for sure). While it's not the same as an actual kernel FS driver (performance in particular), it effectively allows what you're asking for by exposing an API you can write a filesystem driver against without it being part of the kernel code.

Re: Linus: Don't Use ZFS

#109
Honestly, at this point if I can't get ZFS in Linux I would move to FreeBSD whenever I need big filesystem. How does Linux® Binary Compatibility layer work on FreeBSD?

Re: Linus: Don't Use ZFS

#110

Earlier quoted context omitted.

ZFS is not really GPL-incompatible either, but it doesn't matter. Between FUD and Oracle's litigiousness, the end result is that there is no way to overcome the impression that it is GPL-incompatible. But it is a problem that you can't reliably have out-of-tree modules. Also, Linus is wrong: there's no reason that the ZoL project can't keep the ZFS module in working order, with some lag relative to updates to the Lin…

> But it is a problem that you can't reliably have out-of-tree modules. That is the bit I'm trying to get at. Yes it would be best if ZFS was just part of Linux, and maybe some day it can be after Oracle is dead and gone (or under a new leadership and strategy). But it's almost beside the point. Every other OS supports installing drivers that aren't "part" of the OS. I don't understand why Linux is so hostile to this…

I'm not sure Linux is especially hostile. A new OS version of, say, Windows can absolutely break drivers from a previous version.
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