Use DRBD 8.4's support for changing network options on the fly

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DRBD 8.4 theoretically supports changing network options on the fly. This would 
be very useful for instance migration, as we could change to multi-primary mode 
without detaching, reattaching and resyncing.

Unfortunately, DRBD 8.4.2 and DRBD 8.4.3 have bugs when using this feature. 
They loose synchronization, especially when a lot of IO is going on.

See the following discussion for further details:
http://article.gmane.org/gmane.comp.linux.drbd/25592
http://article.gmane.org/gmane.comp.linux.drbd/25593
http://article.gmane.org/gmane.comp.linux.drbd/25605

As the support has already been implemented (patches are attached to this bug), 
we should re-test newer DRBD versions as they appear.

Original issue reported on code.google.com by thoma...@google.com on 7 May 2013 at 2:04

• Blocking: #273

Attachments:

• 0001-Make-DRBD-net-options-support-queryable.patch
• 0002-Add-more-unittests-for-the-DRBD8-class.patch
• 0003-Optimize-instace-migration-when-using-DRBD-8.4.patch

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Original comment by thoma...@google.com on 11 Dec 2013 at 8:39

• Now blocking: #273

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Unassigning myself as I won't be able to look into this.

Original comment by thoma...@google.com on 20 May 2014 at 7:57

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Original comment by hel...@google.com on 20 May 2014 at 8:18

• Added labels: Milestone-Release2.13, Priority-High, Type-Enhancement