[DRBD-user] database on drbd

Todd Denniston Todd.Denniston at ssa.crane.navy.mil
Thu Apr 1 18:49:26 CEST 2004

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


Lars Ellenberg wrote:
> 
<SNIP>
> Correct from concept.
> BUT: unfortunately not implemented (in 0.6.x) :(
> 
> The 0.6.X series does NOT yet have a persistent
> bitmap, which is needed for the "Quick" sync.
> So after the reboot, there is no way for the nodes to *know* that only
> alittle bit has changed. The only thing they know is that one was
> primary, without seeing the other one, and then went down.
> 
> So in 0.6.x we need a full synchronization
>  * whenever a connected Primary node went down (crash)
>  * whenever a UNconnected Primary node changed state
> 
> Or, to put it the other way, we ONLY have a "Quick" sync,
> if the current Primary stays up, i.e. Secondary fails an rejoins,
> or the much more likely case of a replication network hickup.
> 
> In 0.7 we have not only a persistent bitmap, but also an "activity log".
> So this situation dramatically improves.
> We are currently in the process of deploing an automatic test harness
> driven beat-all-remaining-bugs-out-of-it cluster ...
> But it will still need some time to have 0.7 production quality.

Thanks for the update.  Understanding why things happen makes them soooo much
easier to live with.
 From information you posted earlier I have configured my drbd.conf with 
disk-size = physical_partition_size - 128MB
so when 0.7 gets to production quality I can think about moving over.
Too bad it's not ready, I need to make this thing active today. :}

-- 
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane) 
Harnessing the Power of Technology for the Warfighter



More information about the drbd-user mailing list