[Lustre-discuss] lustre interoperability

[Jody McIntyre]

Hi Jeff,

On Fri, Oct 12, 2007 at 12:01:04PM -0400, Jeff Blasius wrote:

> I've seriously trekked through the lustre documentation and haven't
> found an answer regarding this. Is there an official policy regarding
> interoperability among different versions of various lustre
> components?

By coincidence, I just sent information about this to our documentation
team.  It should eventually reach the manual.  Here it is:

---
Our supported upgrades are from one minor version to another, for
example 1.4.10 to 1.4.11 or 1.6.2 to 1.6.3, and also from the latest
1.4.x version to the latest 1.6.x version, so 1.4.11 to 1.6.3 is
supported.

We also support downgrades within the same ranges.  For example, if you
upgrade from 1.6.2 to 1.6.3, you can also downgrade to 1.6.2 (but a
fresh install of 1.6.3 is _not_ guaranteed to be downgradeable.)

Note that other combinations will work and we support them in specific
cases when requested by customers, but the ranges above will always
work.
---

> For example (and I'm sure other groups are in the same boat here),
> it's relatively painless to perform a rolling upgrade to the lustre
> clients, but upgrading the OSS or MDS takes more convincing. Is it OK
> for me to run a patched but 1.6.0 based OSS with a 1.6.3 client? In
> this case all of the lustre components (kernel, lustre, ldiskfs) are
> the same version for each host. Similarly, is it OK to run a lustre
> kernel version out of sync with the userland tools? For example a
> 1.6.0 kernel with a 1.6.3 lustre build on the same host?

Not necessarily.  You should do a rolling upgrade to 1.6.1, then 1.6.2,
then 1.6.3.  Upgrading will be easier if you stay more current - 1.6.0
is fairly old at this point.

Having said that, I believe 1.6.0 and 1.6.3 is actually something that
will work, but I'm not 100% certain of this, so I'll allow others to
correct me.

Cheers,
Jody

> I understand that many of these combinations do in fact work, I'm more
> interested if they're likely to lead to data corruption or client
> evictions. I'm not sure how often incompatibilities arise, but if it's
> relatively rare, it would be useful if that was announced on the
> change log. Of course if there's a serious "Do at your own risk"
> policy that would also be useful to know.
> 
> Thank You,
>                      jeff
> 
> -- 
> Jeff Blasius / jeff.blasius at yale.edu
> Phone: (203)432-9940  51 Prospect Rm. 011
> High Performance Computing (HPC)
> Linux Systems Design & Support (LSDS)
> Yale University Information Technology Services (ITS)
> 
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