[cdwg] Lustre Maintenance Release Plan

[Diego Moreno]

Hi CDWG,

First of all, thanks for this very interesting point you are dealing 
with. I think that this release plan really fits in with what Lustre 
community expects from Lustre and the resources available for testing 
new releases. But there's still one point which is not totally clear for 
me: rolling upgrades between releases. I suppose this plan means that a 
proper transition between maintenance releases is guaranteed but what 
about feature releases? If I take the example of 1.6, 1.8 and 2.1 I 
guess it'd be something like:

- From 2.1, upgrade to 2.2, 2.3 and 2.4 would be possible.

- It wouldn't be possible to upgrade from 2.1 to 2.5, 2.6 or 2.7 without 
going through the next maintenance release (2.4).

So, in consequence, and with regard to maintenance releases:

- At the end of life of a maintenance release (for instance, September 
2014 for Lustre 2.1), even if a new maintenance release is available 
(Lustre 2.7) upgrading would not be possible without going though the 
previous maintenance release (lustre 2.4).

What do you think?

Diego

On 07/31/2012 03:46 AM, Christopher J. Morrone wrote:
> Lustre Maintenance Release Plan
> -------------------------------
>
> Lustre maintenance branches host the releases of lustre that we shall
> advertise to the general public as "stable" releases.  The goal of a
> maintenance branch is to include only bug fixes, to ensure a stable
> releases for a significant period of time.
>
> We currently have a development cadence that puts out a "feature"
> release of Lustre every 6 months.  This is going reasonably well, and 
> we plan to continue that process.  However, we do not have the 
> resources to ensure that every six month release is entirely bug-free, 
> nor do we have the resources to add a new branch every six months that 
> will receive only bug, and be maintained for years.  We are not able 
> to reasonably support and test that many branches in parallel at our 
> current level of investment, nor would we wish to, as the testing 
> requirements rise exponentially as the number of supported branches 
> increases.
>
> We have decided that every third feature release, occurring every 18
> months, will also be the beginning of a maintenance branch.  Tagged
> maintenance releases along the maintenance branch will occur on an
> as-needed basis, according to the demands of discovered bugs and their
> severity.  It is likely that tags will occur more frequently early in
> the branch's lifetime, and taper off in the later months and years.
>
> We plan to make the initially advertised lifetime of a maintenance
> branch three years.
>
> We agreed that Lustre 2.4 will begin the next maintenance branch, which
> has a targeted release date of the end of March, 2013.
>
> None of this precludes ad-hoc maintenance releases on other branches. 
> For instance, there was discussion in the CDWG that some institutions 
> plan to run Lustre 2.3, and may need a "mini-maintenance" release to 
> hold them over until Lustre 2.4.  We just note that those 
> "mini-maintenance" releases will be made as the participants have the 
> time and desire to work on them, and that they will be made on an 
> as-needed, and ad-hoc manner.
>
> We will continue to refine our terminology to help avoid confusion.
>
> To reiterate, out basic plan of record is:
>
>  - Next official maintenance branch will be 2.4 (end of March 2013)
>  - Official maintenance branches will start every 18 months
>  - Official maintenance branches will be supported for 3 years
>
> Chris
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