[DRBD-user] Resynchronization

[Miloš Kozák]

Hi,
I am running DRBD on my two ScientificLinuxes 6.3 with DRBD in version 
8.4.3 in Primary/Primary configuration. I had to turn off one server 
(node1) because of maitanance. It was down almost a week. When I turned 
it on, I didnt not bring up the bond0 interface that interconnects these 
two servers. Then I got

cat /proc/drbd
version: 8.4.3 (api:1/proto:86-101)
GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by 
mockbuild at Build64R6, 2013-07-06 12:36:38

I assume that it is pretty fine? Today I was planing to turn it on so I 
prepared a testing environmnet where I tested split-brain and the its 
recovery, such that I have interconnecting interface down:

victim# drbdadm secondary disk0
victim# drbdadm disconnect disk0

I turn on the interconnecting interfaces

victim# drbdadm connect --discard-my-data disk0
survivor# drbdadm connect disk0

And when all is in sync I put the victim back to primary state:
victim# drbdadm primary disk0.

Everything works just fine so I decided to get back to the production 
servers. I fixed connection between the two servers, ran two commands

victim# drbdadm secondary disk0
victim# drbdadm disconnect disk0

and then got on the victim (node1)

version: 8.4.3 (api:1/proto:86-101)
GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by 
mockbuild at Build64R6, 2013-07-06 12:36:38
  0: cs:Connected ro:Secondary/Primary ds:Diskless/UpToDate C r-----
     ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0

Then I just tried
victim# drbdadm connect --discard-my-data disk0

And the got on node1
version: 8.4.3 (api:1/proto:86-101)
GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by 
mockbuild at Build64R6, 2013-07-06 12:36:38
  0: cs:Unconfigured

What I really worry is what caused the Diskless state on the victim and 
what happens if I run

survivor# drbdadm connect disk0

Thanks Milos