Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

utcc.utoronto.ca

Post reply on HN
Print view View original

41–50 of 124 posts

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#41

Post by nabla9 »

spindle wrote: post #14
diffeomorphism wrote: post #13

Earlier quoted context omitted.

Can you comment on btrfs by comparison? Also, what is the status of the license incompatibility/integration of ZFS with distros? Canonical seems to think that shipping it with ubuntu is legal, but other distros seem less sure.

It's trivial to use ZFS on NixOS, including on the root partition. The legal position is that ZFS is open source under a copyleft license but that many people think that it's illegal to bundle it with the Linux kernel because of some (I think unintended) incompatibilities between its license and the Linux kernel's license. Canonical (and some others) disagree, and think that it's legal. It's only the bundling that's…

Even if canonical would be wrong it seems that the change that anyone having a interest to sue Canonical over unintended legal technicality is nil.

ZFS on Linux does not break the intention and spirit of the kernel licence.

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#42

Post by viraptor »

mapgrep wrote: post #40
viraptor wrote: post #17

Earlier quoted context omitted.

Btrfs has pretty much the same features listed above minus the cache drive handling. (You can still get the cache drive behaviour over bcache device) The raid has different modes, so you'll have to decide if what's available is enough for you. You can check the status of each feature here: https://btrfs.wiki.kernel.org/index.php/Status

It’s also still considered experimental and according to kernel.org wiki “under heavy development.” ZFS was released for production use 14 years ago.

https://github.com/torvalds/linux/blob/master/fs/btrfs/Kconf...

None of the options are marked experimental. (Specific features are marked unstable on the status page)

"Under heavy development" does not mean anything about stability. The kernel itself is under heavy development. ZoL is under heavy development. The disk format is stable, which is what matters.

SUSE provides commercial support for btrfs and uses it as the default. That's pretty much as non-experimental as is gets.

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#43

Post by ubercow13 »

StavrosK wrote: post #32

Has anyone noticed really slow deletes on ZFS? I have a home NAS with RAIDZ and deleting a 1 GB file takes about 30 seconds. I asked on IRC repeatedly but the disks just aren't very busy during the delete (or at all) and nobody managed to figure out why this is happening. It's been that way for years throughout various ZFS versions, and it's driving me crazy.

Is it slow if you delete a file locally on the NAS instead of via a network file system?

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#44

Post by StavrosK »

ubercow13 wrote: post #43
StavrosK wrote: post #32

Has anyone noticed really slow deletes on ZFS? I have a home NAS with RAIDZ and deleting a 1 GB file takes about 30 seconds. I asked on IRC repeatedly but the disks just aren't very busy during the delete (or at all) and nobody managed to figure out why this is happening. It's been that way for years throughout various ZFS versions, and it's driving me crazy.

Is it slow if you delete a file locally on the NAS instead of via a network file system?

Yes, "rm " locally is what's slow :/

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#45

Post by drewg123 »

louwrentius wrote: post #28
acd wrote: post #11

Insightful article. Zfs is the best file system. Ability to know that you do not have silent file corruption. Running without raid controllers. Feature to take snapshots super fast without waiting and that take little extra space. You can use Cache SSD with ZFS for read acceleration of physical disk. Transparent file compression. Good command line interface. Now you can take good actions with ZED for example sending…

I would advice people to think about what they need. ZFS is fine, but it is overkill for most home applications and it has a pitfall related to extensibility. https://louwrentius.com/what-home-nas-builders-should-unders... https://louwrentius.com/the-hidden-cost-of-using-zfs-for-you... So it really depends on your needs. Statements as "ZFS is the best filesystem" are so meaningless. P.S. SSD caching often has no tang…

The thing I never see mentioned when the pros and cons of ZFS are discussed is that ZFS is not zero-copy for things like sendfile. This is one reason why we (Netflix) use UFS for serving content rather than ZFS.

This is because ZFS is cached by the ARC, not the normal page cache. ARC is weird, and operates in 8K blocks (like sparc page size), rather than 4K pages. Zero-copy things like sendfile depend on referencing pages in the page cache, and have never been adapted to deal with ARC. So making sendfile zero-copy with ZFS is a hard project that would involve either teaching ARC to "loan" pages to sendfile, or ripping out ARC caching from ZFS and making it use the same page cache that all other filesystems use.

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#46

Post by lscotte »

StavrosK wrote: post #33
acd wrote: post #11

Insightful article. Zfs is the best file system. Ability to know that you do not have silent file corruption. Running without raid controllers. Feature to take snapshots super fast without waiting and that take little extra space. You can use Cache SSD with ZFS for read acceleration of physical disk. Transparent file compression. Good command line interface. Now you can take good actions with ZED for example sending…

I have a home NAS that has an SSD on it for the OS and four HDDs in RAIDZ. Does anyone know if/how I can use a small part/partition of the SSD for the cache? I don't need an entire SSD's worth of cache, and I'd rather not have to buy an extra one.

Yes, you can. It's called L2ARC.

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#47

Post by mapgrep »

viraptor wrote: post #42
mapgrep wrote: post #40

Earlier quoted context omitted.

It’s also still considered experimental and according to kernel.org wiki “under heavy development.” ZFS was released for production use 14 years ago.

https://github.com/torvalds/linux/blob/master/fs/btrfs/Kconf... None of the options are marked experimental. (Specific features are marked unstable on the status page) "Under heavy development" does not mean anything about stability. The kernel itself is under heavy development. ZoL is under heavy development. The disk format is stable, which is what matters. SUSE provides commercial support for btrfs and uses it as…

In the past, when data integrity issues emerged, btrfs devs have stated that it is not ready for production. Has there been an announcement to the contrary? If btrfs is production ready, is this clearly stated somewhere? Solaris has defaulted to ZFS at least since version 11 first released eight years ago.

Update - also it appears Suse enterprise uses btrfs for the root os filesystem but xfs for everything else including by default /home. To me, this seems telling? If it’s so solid why not use it for /home?

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#48

Post by luma »

nabla9 wrote: post #41
spindle wrote: post #14

Earlier quoted context omitted.

It's trivial to use ZFS on NixOS, including on the root partition. The legal position is that ZFS is open source under a copyleft license but that many people think that it's illegal to bundle it with the Linux kernel because of some (I think unintended) incompatibilities between its license and the Linux kernel's license. Canonical (and some others) disagree, and think that it's legal. It's only the bundling that's…

Even if canonical would be wrong it seems that the change that anyone having a interest to sue Canonical over unintended legal technicality is nil. ZFS on Linux does not break the intention and spirit of the kernel licence.

Relying on Oracle not to sue people for questionable reasons seems like a precarious position.

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#49

Post by StavrosK »

lscotte wrote: post #46
StavrosK wrote: post #33

Earlier quoted context omitted.

I have a home NAS that has an SSD on it for the OS and four HDDs in RAIDZ. Does anyone know if/how I can use a small part/partition of the SSD for the cache? I don't need an entire SSD's worth of cache, and I'd rather not have to buy an extra one.

Yes, you can. It's called L2ARC.

Thanks for the tip, I'll look into it and deploy it!

Re: In Praise of ZFS on Linux's ZED 'ZFS Event Daemon'

#50

Post by magnetic »

StavrosK wrote: post #34
m0zg wrote: post #29

Earlier quoted context omitted.

> ZFS is fine, but it is overkill for most home applications Yeah, not having silent data corruption is "overkill", sure. /s Why not use ZFS? It takes 15 seconds to install, and its CLI is fairly intuitive. Works fine. Costs $0. Why not, even for "home" applications? I could see how it could be unsuitable for "entreprise" applications where there are strict performance requirements etc, but for home, I wish I could u…

For one, because of the fact that you can't add an extra disk to your pool if you need to. GP is saying "plan better", no need to get snarky.

What do you mean? I've done this not so long ago on my pool.

https://unix.stackexchange.com/questions/530968/adding-disks...

Post reply on HN