DRBD
Contents
Overview
DRBD is used by Swivel Active Passive (AP) hardware appliances as an HA solution, whereby only one of the appliances is running Swivel to authenticate users. With the AP appliances Tomcat is only running on the Active appliance, the Passive server does not have Tomcat running. The Active appliance has a Virtual IP address (VIP) bound to it, this moves to the other server if it becomes the Active. The Primary server is usually the Active server, and the Standby server the Passive server.
Two sites may be joined through two A/P pairs using a MySQL database within the Swivel appliances, with data shared between Active members of the sites.
Pre-requisites
Swivel Hardware Appliance 2.x
Which version of the appliance am I running?
Active Passive Processes
For an Active Swivel Appliance the CMI will usually show the following processes status:
Tomcat : Running
Heartbeat : Running
Monitor : Running
Database : Running
DRBD : Running
For an Active Swivel Appliance the CMI will usually show the following processes status:
Tomcat : Stopped
Heartbeat : Running
Monitor : Running
Database : Stopped
DRBD : Running
Active Passive Management
AP appliance Swivel Management console should be done through the VIP, unlike A/A appliances. The VIP may also be used for RADIUS authentication, unlike the A/A Appliances. The graphical TURing and Pinpad images can be accessed through the VIP, as the A/A appliances can.
Restart Tomcat on A/P appliances
This is the procedure for restarting Tomcat.
Through the CMI stop mon on the Passive node then the Active Node
Then stop/start/restart tomcat
Then start mon on the Active node then the Passive Node
Failover the Active (Testing the AP Failover)
This will make the Active server Passive, and the Active Server Passive
On the Active server through the CMI stop heartbeat.
The Passive server should become the active server. To return the original sever to Active restart heartbeat.
DRBD status
A/P apliances will list their status in the CMI under DRBD\Status as below
192.168.0.139 192.168.0.140 DRBD Running DRBD Running st:Primary/Secondary st:Secondary/Primary ld:Consistent ld:Consistent ns:90976 ns:208896 DRBD disk partition is active DRBD disk partition is not active
DRBD status can also be viewed from the command line.
/etc/init.d/drbd status
ok
drbd driver loaded OK; device status:
version: 0.7.25 (api:79/proto:74)
GIT-hash: 3a9c7c136a9af8df921b3628129dafbe212ace9f build by mockbuild@v20z-x86-64.home.local, 2009-08-22 12:56:48
0: cs:Connected st:Secondary/Primary ld:Consistent
ns:11196 nr:464740 dw:475936 dr:25166 al:2 bm:362 lo:0 pe:0 ua:0 ap:0
drbd driver loaded OK; device status:
version: 0.7.25 (api:79/proto:74)
GIT-hash: 3a9c7c136a9af8df921b3628129dafbe212ace9f build by mockbuild@v20z-x86-64.home.local, 2009-08-22 12:56:48
0: cs:Connected st:Primary/Secondary ld:Consistent
ns:464872 nr:11196 dw:50084 dr:475334 al:28 bm:86 lo:0 pe:0 ua:0 ap:0
IP Address change for Active Passive Appliances
See IP Address change for Active Passive Appliances
Known Issues
Please contact Swivel before upgrading.
DRBD troubleshooting
Checking communication
ping -I eth1 -c 5 224.0.0.1
should get a reply when run on a A/P pair
Unknown Status
Where the status is Primary/Unknown or Secondary/Unknown, then the A/P may need to be resolved
Example:
drbd driver loaded OK; device status: version: 0.7.25 (api:79/proto:74) GIT-hash: 3a9c7c136a9af8df921b3628129dafbe212ace9f build by mockbuild@v20z-x86-64.home.local, 2009-08-22 12:56:48 Primary 0: cs:WFConnection st:Primary/Unknown ld:Consistent
ns:0 nr:0 dw:9862060 al:10 bm:818 lo:0 pe:0 ua:0 ap:0
drbd driver loaded OK; device status: version: 0.7.25 (api:79/proto:74) GIT-hash: 3a9c7c136a9af8df921b3628129dafbe212ace9f build by mockbuild@v20z-x86-64.home.local, 2009-08-22 12:56:48 Standby 0: cs:WFConnection st:Secondary/Unknown ld:Consistent
ns:0 nr:0 dw:9862060 al:10 bm:818 lo:0 pe:0 ua:0 ap:0
DRBD stop/start and restart
Restart drbd on each of the Swivel server
CMI stop/start
The CMI allows the option to Stop DRBD and to start if stopped.
Command line DRBD options
Restarting drbd
drbd restart
Stopping drbd
drbddisk stop
connecting the drbd servers
drbdadm connect all
Configuring the drbd as a Primary
drbdadm -- do-what-I-say primary all
DRBD manual mount
DRBD manual mount can be used such as for example clearing mysql bin logs. This needs to be done on only one of the nodes, usually the Primary.
1. Stop all services on both nodes starting with the SECONDARY first.
a. Mon
b. Heartbeat
2. On the Primary, mount the drbd partition manually to gain access to the mysql and/or tomcat.
3. To mount the DRBD partition (normally you do this on primary)
a. /etc/ha.d/resource.d/drbddisk start
b. /etc/ha.d/resource.d/Filesystem /dev/drbd0 /drbd ext3 start
4. Now you can manage the /drbd partition and start/stop mysql and/or tomcat independently of heartbeat.
5. Follow the procedure of clearing the mysql bin-logs etc.
6. To dismount the DRBD partition.
a. /etc/ha.d/resource.d/Filesystem /dev/drbd0 /drbd ext3 stop
b. /etc/ha.d/resource.d/drbddisk stop
7. Now start heartbeat to start tomcat in the normal manor and test.
8. Start mon on primary and then heartbeat and mon on secondary.
