[zfs] Re: April OpenZFS Leadership Meeting

Wed Apr 24 14:04:58 UTC 2019

On April 23, 2019 8:46:32 PM UTC, Matthew Ahrens <mahrens at delphix.com> wrote:
>At today's meeting we covered:
>
>Discussions:
>
>   - Making it easier to port commits from ZoL -> other platforms
>   - Enabling compression by default
>   - Updating LZ4 implementation
>
>Announcements:
>
>   - DRAID meetup
>   - ZoL 0.8 status
>   - ZoF (ZoL on FreeBSD) test images
>   - Code of Conduct
>
>Video recording available: https://www.youtube.com/watch?v=dIVGGJaZ7zk
>
>The next meeting will be May 28th at 1PM Pacific time (5 weeks from
>today).
>
>Detailed notes, thanks to Karyn and Serapheim:
>
>   -
>
>   DRAID meetup (Richard Elling)
>   -
>
>      This is an all-day workshop for people interested in using and
>      developing the feature
>      -
>
>      The goal is to finalize the design and start working on it
>      -
>
>      May 3 at the Delphix SF office (343 Sansome St, Suite 900, San
>      Francisco) at 9am
>      -
>
>   Please RSVP so we are sure to have enough space. Reach out to anyone
>      on the team over email, Slack (#draid)
>      -
>
>      Karyn to set up Zoom
>      -
>
>      Richard will pull together an agenda document: remote folks (in
>      particular) can add comments and items to the agenda
>      -
>
>   ZoL 0.8 status (Brian B)
>   -
>
>   Tagged final release candidate last week. FC and soaking since then.
>      -
>
>      Please test it as much as possible!
>      -
>
>      There are a few remaining bugs they are trying to finish up, but
>      there shouldn’t be major changes.
>      -
>
>      Also working on documentation
>      -
>
>      Hoping to release in 2-3 weeks
>      -
>
>   ZoL => FreeBSD: test images available (based on Dec ZoL)! See this
>   announcement
><https://lists.freebsd.org/pipermail/freebsd-stable/2019-April/090915.html>
>   for details. Please test it out.
>   -
>
>   Allan will cross-post the ZoL on FreeBSD announcement to the openzfs
>      list.
>      -
>
>      JoshP: The current ZoL-based implementation doesn't have TRIM
>      enabled, are we dropping it?
>      -
>
>         Darth is waiting for ZoL to reach 0.8 and Delphix to upstream
>  their latest features to ZoL before doing a final rebase for release.
>         Hopefully in 4-6 weeks.
>         -
>
>            This rebase should also include the TRIM changes.
>            -
>
>   Any feedback on Porting ZoL commits to other platforms? (Brian B)
>
>Are there things we can do to make this easier? Problems found during
>porting?
>
>   -
>
>     Igor: Identify pre-platform features, functions, etc. where things
>    have diverged between platforms. How to report issues in a way that
>      provides visibility to all of the platforms?
>      -
>
>     BB: They’ve tried to keep things consistent with illumos, but have
>         likely diverged. Getting some documentation from illumos and
>other folks
>         would help. Source code? Wiki? Mailing list?
>         -
>
>   Jerry J: Has been documenting divergence in the SPL interfaces (that
>      he noticed as he was porting from ZoL to illumos) in the  and
>can send that
>out to the mailing list and we can figure out a better place to put it.
>      -
>
>   Enable compression by default at pool creation (Issue
>   <https://github.com/zfsonlinux/zfs/issues/8213>) (kpande)
>
>The idea is to give a better out of the box experience. The downsides
>are:
>potential CPU cost (and write performance due to compressing) and new
>users
>misunderstanding how the space is used in certain cases.
>
>   -
>
>      Igor: There have been issues when root pools are expecting
>      compression to be disabled (on SPARC?)
>      -
>
>     Allan: This has been the default in FreeBSD installer for ~2 years
>      -
>
>      Sef: Boot pools need to be different for each platform, but grub
>  doesn’t seem like it needs to be different. Sef supports it being the
>      default.
>      -
>
>   Compression=on has been the default in FreeNAS for several years; no
>      complaints
>      -
>
>      *** Someone to take an action item to investigate benefits and
> issues, and write it up? (Matt will put out a call for someone to take
>      ownership of this)
>      -
>
>   Next meeting: push back 1 week (to May 28)?
>   -
>
>      Done!
>      -
>
>   Code of Conduct
>   -
>
>      Send feedback by Apr 29!
>      -
>
>   Allan: Proposal to upgrade the LZ4?
>   -
>
>      In general people are in favor of this
>      -
>
>      The first step is to just update decompression so people get the
>      performance improvements
>      -
>
>  Next is the exploration of enabling the compressor potentially with a
>      tunable that can fall back to the old decompressor
>      -
>
>        The fear is that enabling the new compressor could increase the
>  space usage if using nopwrite (e.g. double it for existing snapshots)
>         -
>
>      Igor: How stable is LZ4+compression?
>      -
>
>      Allan: No known issues that he is aware of.
>
>
>On Mon, Apr 22, 2019 at 9:00 AM Matthew Ahrens <mahrens at delphix.com>
>wrote:
>
>> The next OpenZFS Leadership meeting will be held tomorrow, April 23,
>> 11am-12noon Pacific time (note the earlier than usual time).  We
>don't have
>> much on the agenda for this month, so if there are things you'd like
>to
>> discuss, this is a good opportunity - send me an email :)
>>
>> Everyone is welcome to attend and participate, and we will try to
>keep the
>> meeting on agenda and on time.  The meetings will be held online via
>Zoom,
>> and recorded and posted to the website and YouTube after the meeting.
>>
>> The agenda for the meeting will be a discussion of the projects
>listed in
>> the agenda doc.
>>
>> For more information and details on how to attend, as well as notes
>and
>> video from the previous meeting, please see the agenda document:
>>
>>
>>
>https://docs.google.com/document/d/1w2jv2XVYFmBVvG1EGf-9A5HBVsjAYoLIFZAnWHhV-BM/edit
>>
>> --matt
>>
>
>------------------------------------------
>illumos: illumos-zfs
>Permalink:
>https://illumos.topicbox.com/groups/zfs/T70b8c262d29daaa6-Mfca8e62f8cb12f220806d5cc
>Delivery options: https://illumos.topicbox.com/groups/zfs/subscription

Hello all,

For anecdotal experience regarding root pool compression, the issue was there with older GRUB loader of OpenSolaris and contemporary Solaris 10; I believe it was fixed in the illumos branch after the fork (can't find and point to a commit now, possibly soon after lz4 introduction; no idea about state of later Solaris releases).

The problem manifested by GRUB refusing to read datasets (rpool, rpool/ROOT, rpool/ROOT/$BENAME) that had the compression enabled (even if no blocks were in fact compressed) or disabled at the moment but compressed blocks encountered during a read.

This was one of main reasons early on for my split-root support scripts, so /usr could be separated into a gzip-9'ed dataset and shrink from ~3gb to ~1gb on a default install.

On my current laptop I see rpool has compression=off, rpool/ROOT has lz4 and rootfs(es) inherit that. Works well WRT stability and performance.

Hope this helps,
Jim

--
Typos courtesy of K-9 Mail on my Android