[DRBD-user] DRBD with RHCS

Digimer lists at alteeve.ca
Tue Jun 4 14:57:42 CEST 2013

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 06/03/2013 11:54 PM, Chan Ching Yu, Patrick wrote:
> Hi all,
> I’ve configured DRBD on two nodes running on CentOS6.3, it’s pretty
> good. The disks on two nodes can be synchronized succsssfully.
> master1# cat /proc/drbd
> 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
> ns:204840 nr:2087836 dw:2292676 dr:1037 al:50 bm:128 lo:0 pe:0 ua:0 ap:0
> ep:1 wo:f oos:0
> master2# cat /proc/drbd
> 0: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r-----
> ns:2087836 nr:204840 dw:204840 dr:2087836 al:0 bm:128 lo:0 pe:0 ua:0
> ap:0 ep:1 wo:f oos:0
> However, I came across problem when I integrate RHCS (Redhat Cluster
> Suite) to DRBD.
> I’ve added the DRBD-proivided script
> /usr/local/drbd/share/cluster/drbd.sh as the RHCS resource.
> <rm>
> <resources>
> <ip address="" sleeptime="10"/>
> <drbd name="mdisk" resource="ha"/>
> <script file="/usr/local/drbd/share/cluster/drbd.sh" name="drbd_script"/>
> </resources>
> <service domain="drbd_domain" name="mdisk_svc" recovery="relocate">
> <ip ref=""/>
> <script ref="drbd_script"/>
> </service>
> </rm>
> However,  when I relocate the service to another node, the script does
> not take any effect.
> Then I tried to run this script manually. I guess the reason is the
> script does not know which device to promote/demote.
> [root at master2 ~]# /usr/local/drbd/share/cluster/drbd.sh start
> USAGE: drbdadm primary [OPTION...] {all|RESOURCE...}
>    --stacked, -S
>    --dry-run, -d
>    --verbose, -v
>    --config-file=..., -c ...
>    --config-to-test=..., -t ...
>    --drbdsetup=..., -s ...
>    --drbdmeta=..., -m ...
>    --drbd-proxy-ctl=..., -p ...
>    --sh-varname=..., -n ...
>    --peer=..., -P ...
>    --version, -V
>    --setup-option=..., -W ...
>    --help, -h
> OPTIONS FOR primary:
>    --force[=...]
> Version: 8.4.3 (api:1)
> GIT-hash: 89a294209144b68adb3ee85a73221f964d3ee515 build by
> root at master2.local, 2013-06-01 07:29:10
> No resource names specified
> How to integrate this script (drbd.sh) to RHCS?  Should I feed the
> resource name to RHCS?
> Thanks very much.
> Regards,
> CY

The <script...> resource agent is designed for init.d (like) scripts. 
The agent will pass start, stop and status to that script and will look 
at the exit code to determine success/failure. There is a drbd specific 
resource agent, called 'drbd'. It can handle promoting a node's DRBD 
resource to primary when needed and other such actions.

As an aside, are you using actual fencing? Without it, you will find 
that the cluster locks up when you test fail over.


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