[DRBD-user] fdisk /dev/drbd1 -> Unable to open /dev/drbd1

Rafał Kupka rkupka+Listy.Drbd at pronet.com.pl
Tue Dec 18 14:43:42 CET 2007

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 18, 2007 at 01:56:21PM +0100, Tomasz Chmielewski wrote:
> Rafał Kupka schrieb:

> >Make sure that resource r0 is in primary state on that node.
> Indeed it was the case:
> primary_machine# cat /proc/drbd
> version: 8.2.1 (api:86/proto:86-87)
> GIT-hash: 318925802fc2638479ad090b73d7af45503dd184 build by root at san2, 
> 2007-12-17 13:43:47
>  1: cs:SyncSource st:Secondary/Secondary ds:UpToDate/Inconsistent C r---
>     ns:11704 nr:0 dw:0 dr:19264 al:0 bm:0 lo:0 pe:5 ua:237 ap:0
>         [>...................] sync'ed:  0.8% (1536652/1548204)K
>         finish: 0:28:27 speed: 856 (824) K/sec
>         resync: used:2/31 hits:961 misses:2 starving:0 dirty:0 changed:2
>         act_log: used:0/127 hits:0 misses:0 starving:0 dirty:0 changed:0
> An obvious question would be: why does it sync if both machines are 
> secondary?

Primary/Secondary state is for DRBD device availability. On primary node
you have working /dev/drbdx. Syncing is about disc state ("ds:" in
/proc/drbd). You have ds:UpToDate/Inconsistent -- other node disc is
Inconsistent and sync is needed.

> Let's make it primary:
> primary_machine# drbdadm -- --overwrite-data-of-peer primary all
> Child process does not terminate!
> Exiting.

Use --overwrite-data-of-peer only if DRBD refuses to switch to primary
state and you know that it is necessary.

> So, something was not very happy, but looks like it succeeded:

Does error still happen if you don't use --overwrite-data-of-peer?

> Let's now try to see what happens if we reboot drbd on the primary machine:
> # /etc/init.d/drbd stop
> Stopping all DRBD resources.
> # /etc/init.d/drbd start
> Starting DRBD resources:    [ d0 s0 n0 ].
> Ouch - primary is gone! Why? Do I have to set up the primary each time 
> after drbd starts?

Yes, typically heartbeat DRBD resource agent manage primary/secondary
state of device. I think in your situation (drbd as "backup") small
/etc/init.d/ script on first node is good enough. In case of disaster
you can set primary on other (backup) node manually, right?

Great software without the knowledge to run it is pretty useless.
(Linux Gazette #1)

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