Réf. : Re: alas for thee, EVMS

It would be also great to remove the main lock in /var/lock/evms-engine and
to consider a fine-grained locking system. We've had numerous cases where
the only possible solution to use evms was to reboot the whole server
before.

I think it's the weakest part of EVMS.

Regards

Pierre Gentile



                                                                           
             Jeremy Jackson                                                
             <[email protected]                                              
             et>                                                      Pour 
                                       Andrew Schulman                     
             30/11/2008 19:38          <[email protected]>          
                                                                        cc 
                                       [email protected]    
                                                                     Objet 
                                       Re: [Evms-devel] alas for thee,     
                                       EVMS                                
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





On Fri, 2008-11-28 at 04:30 -0500, Andrew Schulman wrote:

> This was always my favorite feature of EVMS, that it freed us from the
danger
> and drudgery of the kind of procedure I described above.  To this day I
haven't

Add to the feature list, scripted database snapshots...

> found any other software that matches it in that regard.  What a shame
that it's
> been abandoned.

Abandoned by IBM, yes.  I don't believe all hope is lost, yet.  What I
see as the next step, is a re-architecting to integrate with udev (and
possibly HAL on top of that) and upstart.  Ubuntu is moving (albeit
slowly) to an all event-based startup, and integrating device-mapper
with udev.

EVMS's design includes it's own device discovery, from before udev was
popular.  The duplication also causes conflicts.  I would break the
monolithic EVMS device discovery apart, and instead subscribe to udev
events.  Then evms_activate (and that part of evms-cli and evmsn,
evms-gui) would only be used if udev isn't running, perhaps in initrd or
rescue disc applications.  Ubuntu's LVM tools have been modified in this
way already.

EVMS device nodes for compatibility devices would exist in the standard
locations, /dev/device-mapper/ etc. and be managed by udev.

Parts of EVMS that would be reused, are the metadata for named-volumes,
persistent snapshots, and other features, as well as the UI which
coordinates volume expandsion and other complicated operations, between
they various device drivers and partition/segment/region managers.

I see the UI taking the place of special-purpose system installer UIs,
with the addition of "wizard" plugin modules in EVMS, beside the
existing classes of device-driver/segment/region/filesystem plugins.

It may also be interesting to see evmsd reused and/or take on additional
functions, perhaps to maintain volume state and receive events from
udev.

Another recent development is that dm-raid seems to be on the horizon.
md-raid has been a continual source of bugs and delays for EVMS in the
past.

Who has the keys to the sourceforge project anymore?  To revive or to
fork, that is the question.

--
Jeremy Jackson
Coplanar Networks
(519)489-4903
http://www.coplanar.net
[email protected]


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