HeartBeat
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HeartBeat is a high-availability-cluster software for Linux that allows you to make a service highly available without needing some kind of shared storage. The concept is that one cluster node offers a service on a virtual IP-address. When this computer breaks down, another cluster node takes over the virtual ip address and continues serving.
Installation
Architecture
| sense | name | IP | virtual/physical |
|---|---|---|---|
| first cluster node | heartbeat-1 | 192.168.0.21 | virtual |
| second cluster node | heartbeat-2 | 192.168.0.22 | virtual |
| iscsi storage | tweedleburg | 192.168.0.5 | physical |
| virtual IP address | gothere | 192.168.1.1 | virtual |
Process
- On heartbeat-*, install SLES 10 as per default, but I disable ZMD and the firewall.
- On tweedleburg, install an iscsi storage.
- establish passwordless login between heartbeat-1 and -2.
- adapt /etc/hosts on both nodes so that it contains
192.168.0.21 heartbeat-1.site heartbeat-1 192.168.0.22 heartbeat-2.site heartbeat-2
- configure the cluster on node 1
heartbeat-1:~ # yast2 heartbeat
Choose MD5 as auth method and myauth as password.
- install heartbeat on node 2
heartbeat-1:~ # yast -i heartbeat
- propagate the heartbeat configuration
heartbeat-1:~ # scp /etc/ha.d/ha.cf root@heartbeat-2:/etc/ha.d heartbeat-1:~ # scp /etc/ha.d/authkeys root@heartbeat-2:/etc/ha.d
- start the cluster
heartbeat-1:~ # /etc/init.d/heartbeat start heartbeat-2:~ # /etc/init.d/heartbeat start
- set a password for the hacluster admin
heartbeat-1:~ # passwd hacluster
- configure the cluster
heartbeat-1:~ # hb_gui
Log in as hacluster user to heartbeat-1
- build sfex from http://www.linux-ha.org/sfex on both nodes
- set up an iscsi initiator on both nodes, we assume it makes the device /dev/sdb.
- test sfex by locking /dev/sdb
heartbeat-1:~ # /usr/lib64/heartbeat/sfex_init /dev/sdb heartbeat-1:~ # /usr/lib64/heartbeat/sfex_lock /dev/sdb acquired lock successfully. heartbeat-1:~ # /usr/lib64/heartbeat/sfex_stat /dev/sdb control data: magic: 0x01, 0x1f, 0x71, 0x7f version: 1 revision: 3 blocksize: 512 numlocks: 1 lock data #1: status: lock count: 2 nodename: heartbeat-1 status is LOCKED.
- test the other cluster node realizes the lock:
heartbeat-2:~/sfex-1.3 # /usr/lib64/heartbeat/sfex_stat /dev/sdb control data: magic: 0x01, 0x1f, 0x71, 0x7f version: 1 revision: 3 blocksize: 512 numlocks: 1 lock data #1: status: lock count: 2 nodename: heartbeat-1 status is UNLOCKED.
Configure cluster resources
In the hb_gui program, you add a new resource group named resource_group. You add the first resource, the sfex device. You add the start, stop and monitor operations to this.
Commands
To see if your cluster is up and running, use the cluster resource manager, i.e. like this:
crm_mon -i5