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

Lars Ellenberg lars.ellenberg at linbit.com
Fri Sep 21 10:34:08 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 Tue, Sep 18, 2012 at 12:24:57PM -0400, Dan Barker wrote:
> "I have read errors on the primary side, which caused the secondary to go
> into an "inconsistent" state."
> It's a shame you lost the logs. They would have said much.

That was exactly the sentence that promted me to explicitly ask for logs.

> 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).

> All I/O is
> going over the wire now, reads and writes; not just writes as is the normal
> (uptodate/uptodate) case.
> You have described a result different than that, so the precipitating events
> must be different too.


> hth
> Dan

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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