[DRBD-user] What to do about read errors on the primary?

Lars Ellenberg lars.ellenberg at linbit.com
Fri Sep 21 11:00:16 CEST 2012

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

On Fri, Sep 21, 2012 at 10:54:11AM +0200, Rasto Levrinc wrote:
> On Fri, Sep 21, 2012 at 10:34 AM, Lars Ellenberg
> <lars.ellenberg at linbit.com> wrote:
> >
> > > When drbd loses a primary disk, it continues to work, read/write, using the
> > > secondary disk. The active node will remain primary, the standby node will
> > > remain secondary, but the disk state will be diskless/uptodate.
> >
> > If you configure it "correctly". Unfortunately, for historical reasons,
> > the "default" on-io-error handling was "pass-on", which is ill labeled,
> > and not very useful either.
> >
> > Always explicitly configure "detach" (or "call-local-io-error",
> > if you have a need for such handler to be triggered).
> That means, if you change the default now, it would probably fix a lot of
> configurations and will not break even one of them. :)

That's why the default in 8.4 is detach.


And yes, we do consider to change it even in 8.3.

Though, maybe, who knows, pass-on became a little bit more useful
recently, and if we find the time to work on it a bit more,
and/or someone sponsors it, it may even start to become really useful,
by triggering a micro resync on local IO errors during normal operation,
thereby fixing this particular failure scenario.


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