Talk:ZFS

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Kernel config

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It should be mentioned that Kernel needs the ZLIB_DEFLATE ( https://github.com/zfsonlinux/spl/commit/42b3ce6) option enabled (which is not directly accessible). Can be enabled by selecting Zlib-compression algorithm in Cryptographic-API of menuconfig.

Feel free to mention it. This is a publicly modifiable wiki. --Maffblaster (talk) 20:01, 30 December 2016 (UTC)

TRIM support?

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Article doesn't mention anything about TRIM(aka discard) support which it appears to be unimplemented: https://github.com/zfsonlinux/zfs/pull/1016 --EmanueLczirai (talk) 13:25, 6 February 2015 (UTC)

If it's not implemented in ZFS, then the article probably doesn't need to mention it... --Maffblaster (talk) 20:01, 30 December 2016 (UTC)

Caveats

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This discussion is done as of 2022-02-22.

Gonna check in with the Gentoo ZFS maintainers, as I think the bugs referenced in the Caveats section have all been closed, although whether the underlying issues are fully resolved remains another matter!! -- veremit (talk) 19:41, 29 June 2017 (UTC)

ZFS 0.8.0

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This discussion is done as of 2022-02-23.

I've had issues recently building after following the guidance here for Installing into the kernel directory (for static installs). The latest version of zfs in the ZFSonLinux GIT repository is 0.8.0-rc1. This version does not appear to need a separate build of spl or zfs-kmod prior to building, and I've successfully built a new kernel today without having to emerge spl or zfs-kmod. This section could be edited to include advice specific to builds incoporating >=zfs-0.8.0. I'll draft some revised guidance, but would appreciate someone reviewing this when I'm done. -- Sdp.williams (talk) 17:39, 10 September 2018 (UTC)

Hmm. Sounds interesting. Haven't recompiled for awhile but looking to do so nowish anyway (testing some EXPERIMENTAL drivers for various wifi chipsets operating in AP mode for an embedded project) so I will take a look and review your text when I get around to it in the next few days. Walter (talk) 23:53, 10 September 2018 (UTC)
Whilst indeed spl has been merged into zfs-kmod and is therefore no longer a zfs dependency, zfs-kmod is still part of the ZoL project and provides the ZFS kernel module. It is therefore intriguing that you have ZFS support without it! Perhaps it is only required if running a ZFS root partition? Diem (talk) 21:16, 1 May 2021 (UTC)

Installing into the kernel directory (for static installs)

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It seens a mistake in the commands, it should copy-buildin the sys-kernel/spl first, and I edit it.--Harleylg (talk)

spl still needed for 0.7.x

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a recent edit says that after 0.7.11 that spl is no longer needed, this is incorrect, the cutoff is at 0.8.0, which is still in release candidate phase. Bunder (talk) 08:47, 11 February 2019 (UTC)

Advise that zfs needs to be emerged before kernel

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Otherwise if building kernel before zfs, then genkernel will complain about missing /sbin/mount.zfs at the initramfs build stage.

Russelld (talk) 09:08, 11 February 2019 (UTC)

Is the disabling of these hardened kernel configs still necessary?

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KERNEL
General Architecture Dependent Options --->
  GCC plug ins  --->  
    [ ]   Randomize layout of sensitive kernel structures 
Security options  ---> 
  [ ] Harden common str/mem functions against buffer overflows

I notice that the only kernel config that is checked for in sys-fs/zfs (both 0.8.5 & 2.0.0_rc6, as of this writing) is BLK_DEV_LOOP if you have test-suite enabled.
sys-fs/zfs-kmod checks for !DEBUG_LOCK_ALLOC, EFI_PARTITION, MODULES, !PAX_KERNEXEC_PLUGIN_METHOD_OR, !TRIM_UNUSED_KSYMS, ZLIB_DEFLATE and ZLIB_INFLATE.
Further, if you have debug set, it also looks for FRAME_POINTER, DEBUG_INFO and !DEBUG_INFO_REDUCED.
Lastly, if you have rootfs set, it wants BLK_DEV_INITRD and DEVTMPFS.
So, no mention of !GCC_PLUGIN_RANDSTRUCT or !FORTIFY_SOURCE.

ShadowCat8 (talk) 22:38, 21 December 2020 (UTC)

Given the text immediately preceding the menuconfig snippet, the intention is to show that ZLIB_DEFLATE must be enabled rather than those two hardening features must be disabled; the snippet merely shows their settings for whomever wrote this section of the article. As your ebuild checking shows, there is no dependency on these hardening settings.

Diem (talk) 20:57, 1 May 2021 (UTC)

"Remerge (sic) sys-fs/zfs-kmod after every kernel compile" - why?

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I am not 100% certain, but I think the warning about needing to re-emerge sys-fs/zfs-kmod after every kernel compile is misleading, or perhaps unnecessary. I assume what it is trying to say is simply that one must re-emerge and install the kernel module every time the kernel is recompiled, which is standard kernel compilation practice. When I first read it (since it is marked as Important!) I got the impression that one ought to only re-emerge the package after a kernel compile, which seems unnecessary since surely doing so will have no effect unless one then installs the kernel modules? What I'm getting at is that I think this warning ought to be re-written for clarity or else simply deleted; this is not a kernel compilation article so we shouldn't be including standard kernel compile guidance IMO. Does anyone else read this warning differently? I don't want to unilaterally delete it if I have misunderstood its meaning! Diem (talk) 21:28, 1 May 2021 (UTC)

I agree with this comment. In my experience it is not necessary to re-emerge sys-fs/zfs-kmod after every kernel compile, but I use a static install and don't use zfs as a module. I do find that, before compiling a new kernel, I need to copy the sys-fs/zfs-kmod source into my kernel source directory as per the static install instructions, otherwise the zfs option will not be enabled under the kernel filesystem options.
If I need to compile the same kernel version with different options, I don't generally require a re-emerge of zfs-kmod as the zfs-kmod source is already present in the kernel source tree. Matrix9 (talk) 10:05, 17 Sep 2022 (UTC)
Much more to ensure to be able to load the modules on the newly compiled kernel. If you have strict version checking, the kernel will not be happy. Another case is internal kernel API changes even on minor versions: a well known recent case is Kernel 6.2.8, issue documented in bug #903117. I have had also bad experiences in the past with DKMS on a Lustre client machine (CentOS so not Gentoo related) where for some reason an updated kernel refused to load required Lustre kernel modules built for the previous kernel version. The retained life rule is: rebuild your out-of-tree modules every time you update the kernel. --Admnd (talk) 14:51, 27 April 2023 (UTC)

Why is ZFS for PORTAGE_TMPDIR Okay Now?

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A note reads:

Gentoo's ZFS maintainers recommend you do not use ZFS (or any other exotic filesystem) on PORTAGE_TMPDIR because Portage has a history of exposing bugs in them. But as of May 2022, it should be fine on ZFS.

The note does not say why this is the case. Can someone please clarify? —JGaz (talk) 20:19, 31 December 2022 (UTC)

It is a very general comment that brings no special facts in. Speaking for myself: If I see compat patches for the next-to-be-released kernel in a OpenZFS release I tend to use that latter kernel version (e.g. official support for Linux 6.1 but compat patches for 6.2, I use Linux 6.2). But sometimes a side effect of this can bring some really weird issues in like this one => bug #761499. --Admnd (talk) 14:29, 27 April 2023 (UTC)

Major revision needed

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Very good content but the information starts to be outdated in 2023. OpenZFS is at 2.1.x, no ebuild in the Gentoo tree for the legacy 0.8.x versions. Definitely worth a general refreshment with enhancements. Is the LLVM patch still needed? --Admnd (talk) 13:59, 27 April 2023 (UTC)

ZFS encryption (caveats)

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I saw the comments. I would tend for now to keep that information even if there are no maintainers for historical reason. At least for some time. It is very old and totally obsolete, it will be removed in the future (and will not be lost forever, the page history will retain it). --Admnd (talk) 11:11, 6 July 2023 (UTC)

Sorry, I'm not sure what you mean here. All of the bugs are very much still relevant. I've been bitten by several of them in the last year. Could you rephrase? --Sam (talk) 16:49, 6 July 2023 (UTC)

Text proofing

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Can an English language native speaker review my texts? Grammar, spelling, etc. Also if some phrases can be enhanced with a richer vocabulary and more elegant structures, please do. --Admnd (talk) 11:11, 6 July 2023 (UTC)

ZFS Evil Tuning Guide

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This link is broken. Now archived in Wayback Machine https://web.archive.org/web/20140704142110/http://www.serverfocus.org/zfs-evil-tuning-guide cheers! Russelld (talk) 12:46, 19 June 2024 (UTC)