[Lustre-discuss] Lustre interoperability between the various 1.6.x releases

[Andreas Dilger]

On Aug 06, 2008  10:29 +0200, Karsten Weiss wrote:
> regarding the Lustre interoperability between the various 1.6.x releases 
> the manual currently says this:
> 
> 13.1 Lustre Interoperability
> 
> For Lustre 1.6.4, the following upgrades are supported:
> [...]
> * One minor version to the next (for example, 1.6.3 > 1.6.4 and 1.4.11 > 
>   1.4.12).
> 
> Could someone please elaborate on this?
> 
> 1. Is it generally okay(^1) to upgrade the patchless clients to 1.6.x+1
>    while the servers are still at 1.6.x?
> 
> 2. Is it generally okay to upgrade the servers to 1.6.5.x+1 while some
>    of the patchless clients are still at 1.6.x?
> 
> My understanding is that both is allowed and supported. Correct?

Yes this is generally supported.  The bug you reference is unfortunate,
because it only shows up after a prolonged idle period on a client, and
when we are testing version interoperability the clients are busy running
tests, so this was missed.

> 3. Is there any required/recommended upgrade order between MDSes and
>    OSSes doing a rolling upgrade from 1.6.x to 1.6.x+1? (Especially
>    when there are active clients)

Generally servers are upgraded before clients, but that is not a hard
requirement for 1.6.x to 1.6.x+1.  In some cases we will require strict
server-before-client upgrades for e.g. 1.8.x->2.0.0, but that will be
documented in the release notes.

> Basically my question is this: Which version combinations between clients, 
> MDSes and OSSes are allowed and which are not?

The hope is that any 1.6.x client/server will work with any 1.4.6+ or
1.8.x client/server.  Due to limited testing resources we cannot possibly
test every combination of client/server versions, so we only claim support
for 1.4.latest to 1.6.x, and 1.6.x to 1.6.x+1 interoperability.  Some
customers run a diverse range of clients & servers together, YMMV.

> ^1: Appart from bugs like
>     https://bugzilla.lustre.org/show_bug.cgi?id=16237

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.