[Pacemaker] DRBD Recovery Policies

[Matthew Palmer]

On Fri, Mar 12, 2010 at 09:48:57AM -0000, Darren.Mansell at opengi.co.uk wrote:
> /proc/drbd on the slave said Secondary/Primary UpToDate/Inconsistent
> while it was syncing data back - so it was able to mount the
> inconsistent data on the primary node and access the files that hadn't
> yet sync'd over?! I mounted a 4GB ISO that shouldn't have been able to
> be there yet and was able to access data inside it..
> 
> Is my understanding of DRBD limited and it's actually able to provide
> access to not fully sync'd files over the network link or something?

Yes, it can.  The primary knows what blocks it is inconsistent for, and if
an IO request comes in for one of those it asks for it from the other node. 
A wonderful bit of magic.

> If so - wow.

Indeed, that was my reaction too when I realised what it was doing.

- Matt