On Wed, May 18, 2011 at 02:51:54PM +0200, motyllo8 wrote: > Hi, > > Thanks for great explanation, it was very helpful for me. > My quick question below... > > > 16.5.2011 16:45 Lars Ellenberg <[email protected]>: > > > On Tue, May 10, 2011 at 12:45:08PM +0200, motyllo8 wrote: > > > Hi, > > > > > > > > > I have cluster in Active/Passive configuration. Currently I am trying > > > to support situation when I/O errors occur. I noticed that in > > > drbd.conf default behaviour is halt node with failed disks. > > > > Default behaviour? > > Certainly not. > > Example configuration maybe, for a certain use case, > > to point out what is possible to configure. > > > > > This is a little bit brutal for me. What kind of other scenarios are > > > here taken into account, if any? > > > > Once a node reaches a state where it cannot service IO requests anymore, > > in certain deployments a fast node failure can improve overall service > > availability. > > > > > I was considering only disconnecting replication for resources where > > > I/O errors occured and then promoting second node, but as I know this > > > is not possible when resource is in Diskless state (btw. why?): > > > > > > drbdadm disconnect myresource > > > > > > > > > > > > 0: State change failed: (-2) Refusing to be Primary without at least one > > > UpToDate disk > > > > > > > > > Command 'drbdsetup 0 disconnect' terminated with exit code 17 > > > > A Primary, that has become Diskless (because IO errors caused it to > > detach, or because of an explicit detach), will refuse to be > > "gracefully" disconnected: Because that would cause the data to become > > unavailable. > > > > A Diskless Primary, while still connected, will service application > > requests just fine via the other node. > > > > So you can pick a convenient time to do a graceful switchover: > > stop the services, demote DRBD on the Diskless node, > > promote it on the other, and start services there. > > > > Or, of course, you could fix the broken disk, > > and re-attach it to the Primary. > > > > > > If you (forcefully) disconnect a Diskless Primary, it can only fail all > > IO requests (there is no data to service them from), or block indefinitely. > > > > So, as I understood it is possible to break connection forcefully? If > yes, could you write how to do that? I take into account that this > operation will break access to resource/data.
Starting with 8.3.10, there is drbdsetup disconnect --force. Of course you can also always "forcefully disconnect" by plugging the cable, playing with iptables, taking the interface down, or otherwise ;-) > > That's why it does not let you do that gracefully. > > It just protects you from shooting yourself. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user
