[DRBD-user] the timing of restarting thread

Lars Ellenberg lars.ellenberg at linbit.com
Mon Jul 26 16:05:19 CEST 2010

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

On Mon, Jul 26, 2010 at 09:55:53PM +0900, Junko IKEDA wrote:
> Hi,
> > If sockets fail in some detectable (by tcp) fashion,
> > (RST, icmp unreachable or similar),
> > both sockets are dropped.
> >
> > Replication is only reestablished once both sockets
> > have successfully be reestablished.
> >
> > If sockets fail in some "strange" way (no RST, no icmp,
> > just a black hole), periodic in-protocol DRBD Ping packets
> > (on the meta socket) would no longer be answered,
> > again both sockets are dropped.
> >
> > If meta data socket is still ok (DRBD Pings are still answered in a
> > timely fashion), but there is no progress on the data socket,
> > read about ko-count.
> Thanks for your classification, I could make myself clear.
> What I want to find out is the third case!
> I set ko-count to 1, but it didn't work, it means DRBD did nothing,
> there was no syslog message about ko-count...
> I think my setup might be still wrong so I will try again.

You need to have writes on the drbd device.  If it is idle, it has no
means to detect that something strange goes on on the network.

And you need to have enough writes. As long as it fits into the socket
buffers, ko-count does not catch it.

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

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