[DRBD-user] Difference Between wtc-timeout and degr-wtc-timeout

Robinson, Eric eric.robinson at pmcipa.com
Tue Oct 3 01:25:04 CEST 2006

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Lars said...

I'll quote the code, to clarify the intention for when
"degr-wfc-timeout" is used:
 /* If I am currently not Primary,
  * but meta data primary indicator is set,
  * I just now recover from a hard crash,
  * and have been Primary before that crash.
  * Now, if I had no connection before that crash
  * (have been degraded Primary), chances are that
  * I won't find my peer now either.
  * In that case, and _only_ in that case,
  * we use the degr-wfc-timeout instead of the default,
  * so we can automatically recover from a crash of a
  * degraded but active "cluster" after a certain timeout.

Hmmm... why not always start both nodes as Secondary with no timeout,
then let heartbeat force the right one to be Primary? Wouldn't that
avoid blocking and split-brain?

Is it possible to set up something like this...

	Cluster fine, connected.
	Pull plug from primary machine A.
	Heartbeat on B takes over, forces drbd on B to be primary.
	Plug machine A back in.
	Heartbeat on A detects it is secondary, forces drbd on A to go

If this is a stupid question, forgive me. I am shameless about showing
my ignorance. :-)

Eric Robinson

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