[DRBD-user] strange split-brain problem

Lars Ellenberg lars.ellenberg at linbit.com
Thu Dec 9 17:04:19 CET 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 Tue, Dec 07, 2010 at 09:22:34PM +0100, Klaus Darilion wrote:
> Things are getting worse:
> Am 07.12.2010 20:36, schrieb Klaus Darilion:
> >>And, BTW, no.
> >>Your /etc/hosts file has zero to do with how DRBD behaves.
> >
> >At least I can reproduce the bad behavior when adding the bug to
> >/etc/hosts. I think it has something todo how I address the disk. The
> >one volume which is working fine is configured with:
> >disk /dev/mapper/cc1--vienna-manager--disk--drbd
> >
> >The other volume which causes the problems is configured with
> >disk /dev/cc1-vienna/cc-manager-templates-drbd
> >which is a symlink to
> >/dev/mapper/cc1--vienna-cc--manager--templates--drbd
> >
> >So, I have no idea why, but it seems that if /etc/hosts is broken then
> >the symlinks are no available when DRBD starts. When after booting up is
> >stop/start the DRBD service, then DRBD attaches to the disks fine. Strange.
> I changed drbd.conf to use the "mapper" devices instead of the symlinks.
> Now after startup all but one of the volumes were attached to the
> local disk. The one failed with:
> block drbd6: refusing attach: md-device too small, at least 2048
> sectors needed for this meta-disk type
> block drbd6: drbd_bm_resize called with capacity == 0
> block drbd6: worker terminated
> block drbd6: Terminating worker thread
> After that I manually attached the device without problems.
> Is this really a problem with a too small device or may it be that
> the device wasn't existing at all?

You have to investigate your boot process more closely then.
It is likely still racy somewhere,
possibly with asynchronous udev involvement.

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

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