[DRBD-user] Consistent device to primary fences remote node

Lars Ellenberg lars.ellenberg at linbit.com
Tue Dec 2 16:00:57 CET 2008

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, Dec 02, 2008 at 10:53:56AM +0100, Federico Simoncelli wrote:
> On Fri, Nov 28, 2008 at 12:05 PM, Lars Ellenberg
> <lars.ellenberg at linbit.com> wrote:
> >> When you correctly shut down the server 2 the drbd service is cleanly
> >> stopped. Running "drbdadm show-gi" shows that "Data was/is currently
> >> up-to-date" is set to 0. This means that the resource is automatically
> >> Outdated.
> >
> > is that so.
> > hm.
> > /me looks up the state handling code...
> > right you are.
> >
> > if we are Connected, and a node voluntarily leaves the cluster,
> > and a drbd fencing policy is configured, and the other node is Primary,
> > then the leaving node is requested to outdate itself prior to disconnect.
> 
> Hi, thank you for your answer. Can you point this part in the code?
> (file/function) Thanks.

be warned, though, the state handling part of the code is not easy to follow.

there are a few "cluster wide" state changes,
clean disconnect being one of them.

drbd_nl_disconnect (in drbd_nl.c) does "_drbd_request_state", changing
only the conn part of the state to Disconnecting.

if it receives "SS_CW_FailedByPeer", it retries,
this time requesting "conn Disconnecting" AND "disk Outdated".

the state handling itself spreads over quite a few functions mainly in drbd_main.c.

> >> I just can't boot a single primary if both nodes were incorrectly shut
> >> down.
> >
> > or if you had a network hickup first.
> > but, right, you get a fencing race on network hickup.
> > nice.
> 
> I think this is a pretty common behaviour, isn't it?

sure.

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

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