[Lustre-discuss] targets start order in Lustre 2.4.3

[Riccardo Murri]

Hello,

The online Lustre manual recommends that Lustre targets are started in
this order[1]: MGT, MDT, OSTs, clients.

[1]: http://build.whamcloud.com/job/lustre-manual/lastSuccessfulBuild/artifact/lustre_manual.xhtml#dbdoclet.50438194_24122

Now we are setting up an HA cluster with Pacemaker, and a strict
ordering directive ("order ... Mandatory: ostXX mdt mgt") results in a
complete restart of all targets if the MGT is migrated. In my
experience (with Lustre 1.8.5) this is most of the time unnecessary,
and Lustre can recover from a single target restart.  However, we have
recently switched to Lustre 2.4.3 and things might have changed.

So the question is: is this order strict (in Lustre 2.4.3), or can a
target be stopped and restarted on another node without affecting the
targets running on other nodes?

Thanks for any help!

Riccardo

--
Riccardo Murri
http://www.gc3.uzh.ch/people/rm

Grid Computing Competence Centre
University of Zurich
Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)
Tel: +41 44 635 4222
Fax: +41 44 635 6888