Re: [BUG] Xen Remus, DRBD Protocol D and old Linux kernels

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Jan 18, 2016 at 09:29:38AM +0000, Ian Campbell wrote:
> Just adding the Remus maintainers to the CC.

ping?
> 
> On Fri, 2016-01-15 at 15:26 -0300, Pato Sáinz wrote:
> > Good evening, people.
> > 
> > More than a bug, it's an issue, a big one IMO.
> > 
> > Even though information on the Remus project and its implementation is kind of
> > scarce on the internet and is usually outdated (the project could use some love
> > on that side of things, though it seems that on the coding side, it's
> > still being
> > properly maintained), there's a huge problem in the current implementation: its
> > storage depends on a custom patch developed for a very old version of DRBD.
> > 
> > Currently, the wiki points that in order to use Remus you must use it
> > with a custom
> > version of DRBD, forked from 8.3.11 (and there's also a patch for
> > 8.3.9). Support
> > for these versions have been dropped for almost 3 years, and they are only
> > compatible with Linux kernels 3.0-3.4: most distros have already dropped these
> > kernels and deleted them from their repositories: even kernel.org plans to drop
> > support for the 3.4 kernel in September this year. Building your own is an
> > unnecessary hassle.
> > 
> > These problems make Remus practically unusable, despite being one of the
> > coolest features Xen has in my honest opinion.
> > 
> > This issue has also been brought up at least once on the DRBD mailing list[1]
> > and until there's more cooperation between the Xen project and LINBIT to
> > develop a more robust Protocol D, they've refused to pull the patch into their
> > tree to be maintained.
> > 
> > It's worth noting that the "official" patch (by rshiriam) is somewhat
> > simple[2][3].
> > 
> > A solution to this for the short term would be to port the patch to the current
> > DRBD version (8.4.7-1) and in the long term, to collaborate with LINBIT so
> > the Xen project doesn't have to maintain their own downstream changes, and
> > we benefit from LINBIT's experience on realiable storage.
> > 
> > The short term solution seems like a very quick one, since the original patch
> > is small-ish, and I've been trying to do it[4] but simply C isn't my strong suit
> > and I don't know much of DRBD's source, even after doing a cursory reading
> > of it.
> > 
> > I know this is an open source project and thus most developers are
> > volunteers, but
> > this kind of issue really is a show-stopper that keeps me (and presumably many
> > other people) from using the awesome feature that Remus is.
> > 
> > [1]: http://lists.linbit.com/pipermail/drbd-user/2013-October/020370.html
> > [2]: http://remusha.wdfiles.com/local--files/configuring-and-installing-remus/drbd-8.3.9-remus.patch
> > [3]: https://github.com/macrosheep/remus-drbd/commit/2685b294f5b416d827bdf446a69c88ab04df50dd
> > [4]: https://github.com/superpatosainz/remus-drbd
> > 
> 
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