[DRBD-user] DRBD user guide - GFS2 - recommendation to lose data?
Section 10.2: "Also, it is recommended to use some of DRBD’s features for automatic recovery from split brain. To do all this, include the following lines in the resource configuration: ... By configuring auto-recovery policies, you are configuring effectively configuring automatic data-loss! Be sure you understand the implications." If these options incur a risk of data loss, why are they recommended? I'm wary of recommending that to our users. https://linbit.com/drbd-user-guide/drbd-guide-9_0-en/#ch-gfs -- Regards, Reid Wahl (He/Him) Senior Software Engineer, Red Hat RHEL High Availability - Pacemaker ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
[DRBD-user] DRBD user guide - GFS2 integration handler missing
There is no "/sbin/kill-other-node.sh". What is the correct handler to use? I found /usr/lib/drbd/stonith_admin-fence-peer.sh. -- Regards, Reid Wahl (He/Him) Senior Software Engineer, Red Hat RHEL High Availability - Pacemaker ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
Re: [DRBD-user] corrupted resource can't be fixed be rolling back to old snapshot
Though i could be wrong here , but what i understand is: After Roll back Scenerio: A( Primary Snapshot rollbacked to time: say 12:10:00 PM) , B(Secondary Snapshot roll backed to time say 12:09:00 PM) Current time say : 12:30:00 PM Now A must have received acks(in the past of ofcource) from B between 12:09:00 to 12:10:00 PM , now at 12:09:01 B says i dont have the data which might have confused A as it must be saying saying that you have already acked me few data , then how can you say now that i don't have the data now.Hence the Error.This is just my thought.Or does DRBD support such scenario, if yes then that is awesome than as that prevent complete resynchronization of data. Anyways with DRBD Down , you can always get the data back from ZVOL snapshot(otr its clone) itself(assuming DRBD metadata doesnot contain actual data ?? ) On Tue, 2 Aug 2022 at 15:04, Roland Kammerer wrote: > On Tue, Aug 02, 2022 at 02:54:02PM +0530, Chitvan Chhabra wrote: > > Unable to see the older thread.May Be it is just me.Request to share > older > > conversation as well please. > > we have an archive: > https://lists.linbit.com/pipermail/drbd-user/2022-July/026252.html > ___ > Star us on GITHUB: https://github.com/LINBIT > drbd-user mailing list > drbd-user@lists.linbit.com > https://lists.linbit.com/mailman/listinfo/drbd-user > ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
Re: [DRBD-user] corrupted resource can't be fixed be rolling back to old snapshot
On Tue, Aug 02, 2022 at 02:54:02PM +0530, Chitvan Chhabra wrote: > Unable to see the older thread.May Be it is just me.Request to share older > conversation as well please. we have an archive: https://lists.linbit.com/pipermail/drbd-user/2022-July/026252.html ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
Re: [DRBD-user] corrupted resource can't be fixed be rolling back to old snapshot
Unable to see the older thread.May Be it is just me.Request to share older conversation as well please. Thanks and Regards, Chitvan Chhabra On Tue, 2 Aug 2022 at 14:34, Joel Colledge wrote: > Hi Michael, > > Are you using the most recent version of drbd-utils? There have been a > few fixes over the years which might be related. > > Perhaps the hardware problems affected the metadata long ago and now > the corrupted metadata is present in all the snapshots. > > If that is not the case, this looks to me more like a bug than a > misunderstanding of how DRBD works. Are you able to reproduce the > issue starting from a fresh volume? It could be that this particular > combination of device size and bitmap slot count triggers a bug that > no-one else has yet encountered. A reproducer would be necessary to > work on fixing it. > > Best regards, > Joel > ___ > Star us on GITHUB: https://github.com/LINBIT > drbd-user mailing list > drbd-user@lists.linbit.com > https://lists.linbit.com/mailman/listinfo/drbd-user > ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
Re: [DRBD-user] corrupted resource can't be fixed be rolling back to old snapshot
Hi Michael, Are you using the most recent version of drbd-utils? There have been a few fixes over the years which might be related. Perhaps the hardware problems affected the metadata long ago and now the corrupted metadata is present in all the snapshots. If that is not the case, this looks to me more like a bug than a misunderstanding of how DRBD works. Are you able to reproduce the issue starting from a fresh volume? It could be that this particular combination of device size and bitmap slot count triggers a bug that no-one else has yet encountered. A reproducer would be necessary to work on fixing it. Best regards, Joel ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
Re: [DRBD-user] Regarding Best way for snapshotting with ZFS/LVM as backing disk for drbd
Many Thanks for valuable suggestions and sharing your experiences. On Mon, 1 Aug 2022 at 22:26, GM wrote: > But Why do we need to preserve the metadata via snapshot at the first >> place as it is believed that once you rollback the using the snapshot drbd >> would get confused and would attempt resynchronisation of the entire device >> again any way >> > > Consider the following scenario, Two nodes A and B. A is the Primary and B > is the Secondary. You create a zfs snapshot (both data and drbd metadata) > at 08:00 am on both nodes. At 08:30 am you realise that a serious > corruption has taken place and you urgently need to rollback *both* nodes > from the snapshot created at 08:00 am. You execute a zfs rollback on both > nodes while the drbd resource is down of course. Before bringing the drbd > resource up on both nodes, you must decide which way the replication must > take place (e.g A -> B or B -> A). Once you decide, bring the resource up. > If all goes well, drbd should bring up the resource on both nodes *without* > needing to do a full sync but rather just a small increment instead, as the > metadata is consistent on both nodes (as it was at the time the snapshot > was taken). So it's important to snapshot the drbd metadata on both nodes, > if you want to prevent a full sync. > > >> 3) Do i need to suspend-io first before taking the snapshot and then >> check up to date Status mandatorily ? >> > > Ideally yes but that depends if the layers above drbd supports that > functionality. For example, I'm using qemu VMs on top of drbd/zvol. QEMU > can suspend i/o before issuing a qemu based snapshot (via guest tools) > which then it will propagate at the layers below (e.g drbd -> zfs). If the > layers above drbd cannot handle this, and you could simply take a snapshot > at the layer below drbd (zfs in this case), then that would have the same > effect as when removing the power from the physical machine (e.g the data > would still be consistent due to zfs transaction based nature, but you may > or may have have not lost the last few writes issued by the layers above). > > ___ > Star us on GITHUB: https://github.com/LINBIT > drbd-user mailing list > drbd-user@lists.linbit.com > https://lists.linbit.com/mailman/listinfo/drbd-user > ___ Star us on GITHUB: https://github.com/LINBIT drbd-user mailing list drbd-user@lists.linbit.com https://lists.linbit.com/mailman/listinfo/drbd-user
