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I usually find people running ZFS to run into way too many more problems than what other people run using Ext4. (Edit: I'm surprised to see how people run into

I usually find people running ZFS to run into way too many more problems than what other people run using Ext4. (Edit: I'm surprised to see how people run into issues with Btrfs) It might be good for some specific purposes but I'd reckon the majority of people using it do not fall into those. Using it "just because" is probably more trouble than worth. > ZFS really wasn't in use, ever! But at the same time, it was eating over 30% of CPU capacity! Whaaat?? Interesting bug, sounds like the best option is to not even have the module loaded then. (Not blaming the developers here, necessarily, but yeah, it's a bug)

pseudalopex 5y ago
Btrfs gave me the most trouble by far. And most people say the same in my experience. Replicating half of ZFS's features with ext4 is a whole lot of trouble too.
- usefulcat 5y ago
  We have a machine that has a large ZFS storage pool, and one smaller btrfs volume on a pair of SSDs. If I delete a large directory hierarchy on the btrfs volume and then run sync, it locks up the entire machine for 5-10 minutes. WTF. Nothing like that ever happens with ZFS or ext4.
azalemeth 5y ago
I've had a lot to learn with zfs, but it's never just flat out lost my data, unlike btrfs (in about 2017)
- teekert 5y ago
  Raid5?
  - dkh 5y ago
    Not sure if you are suggesting RAID5 as a relevant problem or solution, but it's arguably the former! :) Regardless, ZFS has configurations equivalent to most "traditional" RAID options anyway (raidz1 is their RAID5) but with the added benefits of all the other great stuff ZFS gives you, like checksums, compression, deduplication, snapshots, etc.
    - teekert 5y ago
      Indeed the read5 implementation was (is?) notorious for some time (or still), well if you Google you'll soon find the stories.
    - ncmncm 5y ago
      Probably it was a guess that you were using a RAID5 mode of Btrfs, and that it was the reason for the failure. Not using RAID5 or RAID6 modes on Btrfs is the first piece of advice people considering Btrfs get.
      - teekert 5y ago
        You are now even warned by mkfs.btrfs itself when you attempt to do it. [0] [0]: https://www.phoronix.com/scan.php?page=news_item&px=Btrfs-Warning-RAID5-RAID6 https://www.phoronix.com/scan.php?page=news_item&px=Btrfs-Wa...
      - dkh 5y ago
        Right, I failed to parse the comment as inquiring as to if that's the Btrfs issue referred to. Yes, I am familiar with Btrfs' RAID blunder. Somewhat ironic though since RAID5 is rarely the best idea regardless of the system implementing it
- daddylongstroke 5y ago
  Consider yourself lucky. There are data-corruption bugs all over the now-diverged ZFS codebase(s). Check the Solaris 11 SRU notes from the last 24 months for many examples.
isatty 5y ago
Usually in my experience whenever someone has a problem with zfs it’s solvable in one way or another and the devs are very responsive on irc and GitHub. On the other hand a lot of problems caused by btrfs is unrecoverable and a mess. Ext4 is stable but lacks the feature set that makes customers go to zfs instead (and that is fine, software should do one thing well and right).
sirius87 5y ago
For a homelab use-case, I backed out of creating a ZFS mirrored storage pool for network storage. It wasn't that the steps were too complicated or that ZFS let me down as such. Just that RAID in general and ZFS put my files in a blackbox, and that I didn't really need a significant boost in network reads. I settled for plain old ext4 and periodic rsync mirror files to another disk (I don't mind some interim data loss + writes are fast). Use SFTP or sshfs for accessing the drive.
- isatty 5y ago
  Any RAID solution that does block/bit level striping will be a “blackbox” as you describe it. That’s not a bad thing (nor is your approach) but pros and cons.
  - dkh 5y ago
    Yup, and as far as "blackbox" solutions go, if something horrible should happen to your system, you want something that works like ZFS as opposed to, say, some high-performance but proprietary hardware RAID. As someone who has a couple times needed to rip 100tb of ZFS disks out of something, put them into a different machine with a different architecture or OS in some random order, and access everything without having lost anything, it's hard for me to overstate how great it is that such a thing is even possible.
    - pdimitar 5y ago
      How exactly did you do that? I'm learning ZFS still and I'm planning to move some of the disks in my first NAS to a better machine. Which ZFS commands?
      - Filligree 5y ago
        Nothing special is necessary. All you need to do is import the pool as normal. There’s a potential problem, in that you can’t import a poll on an OS version that lacks the feature flags that are enabled on the pool. The way to solve that is to choose a common subset when creating the pool.

pseudalopex 5y ago

Btrfs gave me the most trouble by far. And most people say the same in my experience. Replicating half of ZFS's features with ext4 is a whole lot of trouble too.

usefulcat 5y ago
We have a machine that has a large ZFS storage pool, and one smaller btrfs volume on a pair of SSDs. If I delete a large directory hierarchy on the btrfs volume and then run sync, it locks up the entire machine for 5-10 minutes. WTF. Nothing like that ever happens with ZFS or ext4.

azalemeth 5y ago

I've had a lot to learn with zfs, but it's never just flat out lost my data, unlike btrfs (in about 2017)

teekert 5y ago
Raid5?
- dkh 5y ago
  Not sure if you are suggesting RAID5 as a relevant problem or solution, but it's arguably the former! :) Regardless, ZFS has configurations equivalent to most "traditional" RAID options anyway (raidz1 is their RAID5) but with the added benefits of all the other great stuff ZFS gives you, like checksums, compression, deduplication, snapshots, etc.
  - teekert 5y ago
    Indeed the read5 implementation was (is?) notorious for some time (or still), well if you Google you'll soon find the stories.
  - ncmncm 5y ago
    Probably it was a guess that you were using a RAID5 mode of Btrfs, and that it was the reason for the failure. Not using RAID5 or RAID6 modes on Btrfs is the first piece of advice people considering Btrfs get.
    - teekert 5y ago
      You are now even warned by mkfs.btrfs itself when you attempt to do it. [0] [0]: https://www.phoronix.com/scan.php?page=news_item&px=Btrfs-Warning-RAID5-RAID6 https://www.phoronix.com/scan.php?page=news_item&px=Btrfs-Wa...
    - dkh 5y ago
      Right, I failed to parse the comment as inquiring as to if that's the Btrfs issue referred to. Yes, I am familiar with Btrfs' RAID blunder. Somewhat ironic though since RAID5 is rarely the best idea regardless of the system implementing it
daddylongstroke 5y ago
Consider yourself lucky. There are data-corruption bugs all over the now-diverged ZFS codebase(s). Check the Solaris 11 SRU notes from the last 24 months for many examples.

isatty 5y ago

Usually in my experience whenever someone has a problem with zfs it’s solvable in one way or another and the devs are very responsive on irc and GitHub. On the other hand a lot of problems caused by btrfs is unrecoverable and a mess. Ext4 is stable but lacks the feature set that makes customers go to zfs instead (and that is fine, software should do one thing well and right).

sirius87 5y ago

For a homelab use-case, I backed out of creating a ZFS mirrored storage pool for network storage. It wasn't that the steps were too complicated or that ZFS let me down as such. Just that RAID in general and ZFS put my files in a blackbox, and that I didn't really need a significant boost in network reads. I settled for plain old ext4 and periodic rsync mirror files to another disk (I don't mind some interim data loss + writes are fast). Use SFTP or sshfs for accessing the drive.

isatty 5y ago
Any RAID solution that does block/bit level striping will be a “blackbox” as you describe it. That’s not a bad thing (nor is your approach) but pros and cons.
- dkh 5y ago
  Yup, and as far as "blackbox" solutions go, if something horrible should happen to your system, you want something that works like ZFS as opposed to, say, some high-performance but proprietary hardware RAID. As someone who has a couple times needed to rip 100tb of ZFS disks out of something, put them into a different machine with a different architecture or OS in some random order, and access everything without having lost anything, it's hard for me to overstate how great it is that such a thing is even possible.
  - pdimitar 5y ago
    How exactly did you do that? I'm learning ZFS still and I'm planning to move some of the disks in my first NAS to a better machine. Which ZFS commands?
    - Filligree 5y ago
      Nothing special is necessary. All you need to do is import the pool as normal. There’s a potential problem, in that you can’t import a poll on an OS version that lacks the feature flags that are enabled on the pool. The way to solve that is to choose a common subset when creating the pool.