Re: dropping filestore+btrfs testing for luminous

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> Op 30 juni 2017 om 18:48 schreef Sage Weil <sage@xxxxxxxxxxxx>:
> 
> 
> On Fri, 30 Jun 2017, Lenz Grimmer wrote:
> > Hi Sage,
> > 
> > On 06/30/2017 05:21 AM, Sage Weil wrote:
> > 
> > > The easiest thing is to
> > > 
> > > 1/ Stop testing filestore+btrfs for luminous onward.  We've recommended 
> > > against btrfs for a long time and are moving toward bluestore anyway.
> > 
> > Searching the documentation for "btrfs" does not really give a user any
> > clue that the use of Btrfs is discouraged.
> > 
> > Where exactly has this been recommended?
> > 
> > The documentation currently states:
> >
> > http://docs.ceph.com/docs/master/rados/configuration/ceph-conf/?highlight=btrfs#osds
> > 
> > "We recommend using the xfs file system or the btrfs file system when
> > running mkfs."
> > 
> > http://docs.ceph.com/docs/master/rados/configuration/filesystem-recommendations/?highlight=btrfs#filesystems
> > 
> > "btrfs is still supported and has a comparatively compelling set of
> > features, but be mindful of its stability and support status in your
> > Linux distribution."
> > 
> > http://docs.ceph.com/docs/master/start/os-recommendations/?highlight=btrfs#ceph-dependencies
> > 
> > "If you use the btrfs file system with Ceph, we recommend using a recent
> > Linux kernel (3.14 or later)."
> > 
> > As an end user, none of these statements would really sound as
> > recommendations *against* using Btrfs to me.
> > 
> > I'm therefore concerned about just disabling the tests related to
> > filestore on Btrfs while still including and shipping it. This has
> > potential to introduce regressions that won't get caught and fixed.
> 
> Ah, crap.  This is what happens when devs don't read their own 
> documetnation.  I recommend against btrfs every time it ever comes up, the 
> downstream distributions all support only xfs, but yes, it looks like the 
> docs never got updated... despite the xfs focus being 5ish years old now.
> 
> I'll submit a PR to clean this up, but
>  
> > > 2/ Leave btrfs in the mix for jewel, and manually tolerate and filter out 
> > > the occasional ENOSPC errors we see.  (They make the test runs noisy but 
> > > are pretty easy to identify.)
> > > 
> > > If we don't stop testing filestore on btrfs now, I'm not sure when we 
> > > would ever be able to stop, and that's pretty clearly not sustainable.
> > > Does that seem reasonable?  (Pretty please?)
> > 
> > If you want to get rid of filestore on Btrfs, start a proper deprecation
> > process and inform users that support for it it's going to be removed in
> > the near future. The documentation must be updated accordingly and it
> > must be clearly emphasized in the release notes.
> > 
> > Simply disabling the tests while keeping the code in the distribution is
> > setting up users who happen to be using Btrfs for failure.
> 
> I don't think we can wait *another* cycle (year) to stop testing this.
> 
> We can, however,
> 
>  - prominently feature this in the luminous release notes, and
>  - require the 'enable experimental unrecoverable data corrupting features =
> btrfs' in order to use it, so that users are explicitly opting in to 
> luminous+btrfs territory.
> 
> The only good(ish) news is that we aren't touching FileStore if we can 
> help it, so it less likely to regress than other things.  And we'll 
> continue testing filestore+btrfs on jewel for some time.
> 
> Is that good enough?

Sounds good to me. Every cluster I run into runs XFS. People running btrfs did that deliberately and by adding that flag you encourage them to go to BlueStore.

Wido 

> 
> sage
> 
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