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, Sep 25, 2017 at 01:25:34PM -0400, Digimer wrote:
> On 2017-09-25 07:28 AM, Lars Ellenberg wrote:
> > On Sat, Sep 23, 2017 at 11:32:42PM -0400, Digimer wrote:
> >> I tried updating an 8.3.19 DRBD install (on EL6.9), and when I tried to
> >
> > 8.3.16 is the latest I know... typo I assume.
>
> Yup, typo. Was late...
>
> >> connect the updated node to the older node, I got this error:
> >>
> >> ==[ old node ]==
> >> Sep 23 23:13:47 an-a02n02 kernel: block drbd1: incompatible after-sb-0pri settings
> >
> > You have incompatible "after-sb-0pri" settings.
>
> I saw that, but the docs said the config was backwards compatible and
> the after-sb-0pri was left as default.
defaults for after split brain recovery procedures have been
"disconnect" for as long as I can remember.
The suggested setting promoted in various examples is discard zero changes,
as that is the only "safe" (non-destructive) setting we have there,
and improves behaviour in case we had a *potential* data divergence
(both nodes primary at some time, during a time period where they have
not been able to communicate, and both already bumped their data
generation uuids), but at least one did not actually change anything yet.
> >> ==[ updated node ]==
> >
> >> Sep 23 23:13:47 an-a02n01 kernel: drbd r0: incompatible after-sb-0pri settings
> >
> >> ====================
> >>
> >> The config is (from 'drbdadm dump'):
> >>
> >> ====
> >> # /etc/drbd.conf
> >> common {
> >> protocol C;
> >> net {
> >> allow-two-primaries;
> >> after-sb-0pri discard-zero-changes;
> >
> > So it claims it does not like this setting,
> > respectively that the handshake expected that setting
> > to be identical on both nodes, but it was not.
>
> Isn't this the default back in 8.3 days? I don't recall ever changing it...
disconnect != discard-zero-changes
I admit we could have put that into the log message (not just that it
differs, but what the currently visible settings are)
> > So if you intend to downgrade to 8.3 from 8.4,
> > while you still have the 8.4 tools installed,
> > do: "drbdadm down all; drbdadm apply-al all"
> > Only then downgrade.
>
> Noted for the future. In this case, I recreated the MD and did a full
> resync.
Always an option ;-)
Lars