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Installation and Configuration of Pacemaker

Introduction

Pacemaker is the logical evolution of Heartbeat, which has merged with other open source software to achieve perfection. Pacemaker is a resource management software. It must be coupled with Corosync which will manage the exchange of information between nodes.

The installation and configuration described here is done on Debian 6.

Installation

For installation, nothing could be simpler on Debian:

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aptitude install pacemaker corosync

Configuration

Corosync

For Corosync configuration, we need to generate encryption keys for intra-cluster information exchange (between nodes):

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> corosync-keygen
Corosync Cluster Engine Authentication key generator.
Gathering 1024 bits for key from /dev/random.
Press keys on your keyboard to generate entropy.
Press keys on your keyboard to generate entropy (bits = 136).
Press keys on your keyboard to generate entropy (bits = 200).
Press keys on your keyboard to generate entropy (bits = 264).
Press keys on your keyboard to generate entropy (bits = 328).
Press keys on your keyboard to generate entropy (bits = 392).
Press keys on your keyboard to generate entropy (bits = 456).
Press keys on your keyboard to generate entropy (bits = 520).
Press keys on your keyboard to generate entropy (bits = 584).
Press keys on your keyboard to generate entropy (bits = 648).
Press keys on your keyboard to generate entropy (bits = 712).
Press keys on your keyboard to generate entropy (bits = 776).
Press keys on your keyboard to generate entropy (bits = 840).
Press keys on your keyboard to generate entropy (bits = 904).
Press keys on your keyboard to generate entropy (bits = 968).
Writing corosync key to /etc/corosync/authkey.

Then send this configuration to the other nodes using scp for example:

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scp -r /etc/corosync root@nodex:/etc/

Then edit the Corosync configuration file on each node, and adapt the network part for each of them:

(/etc/corosync/corosync.conf)

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# Please read the openais.conf.5 manual page

totem {
    version: 2

    # How long before declaring a token lost (ms)
    token: 3000

    # How many token retransmits before forming a new configuration
    token_retransmits_before_loss_const: 10

    # How long to wait for join messages in the membership protocol (ms)
    join: 60

    # How long to wait for consensus to be achieved before starting a new round of membership configuration (ms)
    consensus: 3600

    # Turn off the virtual synchrony filter
    vsftype: none

    # Number of messages that may be sent by one processor on receipt of the token
    max_messages: 20

    # Limit generated nodeids to 31-bits (positive signed integers)
    clear_node_high_bit: yes

    # Disable encryption
    secauth: off

    # How many threads to use for encryption/decryption
    threads: 0

    # Optionally assign a fixed node id (integer)
    # nodeid: 1234

    # This specifies the mode of redundant ring, which may be none, active, or passive.
    rrp_mode: none

    interface {
        # The following values need to be set based on your environment
        ringnumber: 0
        bindnetaddr: 192.168.20.4
        mcastaddr: 226.94.1.1
        mcastport: 5405
    }
}

amf {
    mode: disabled
}

service {
    # Load the Pacemaker Cluster Resource Manager
    ver:       0
    name:      pacemaker
}

aisexec {
        user:   root
        group:  root
}

logging {
        fileline: off
        to_stderr: yes
        to_logfile: no
        to_syslog: yes
    syslog_facility: daemon
        debug: off
        timestamp: on
        logger_subsys {
                subsys: AMF
                debug: off
                tags: enter

Finally, edit the /etc/default/corosync file to tell it to start at machine boot:

(/etc/default/corosync)

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 # start corosync at boot [yes|no]
 START=yes

Now let's activate our new configuration on all nodes:

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/etc/init.d/corosync restart

Now we can check the status of the cluster:

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> crm_mon --one-shot -V
crm_mon[427]: 2010/12/20_21:51:54 ERROR: unpack_resources: Resource start-up disabled since no STONITH resources have been defined
crm_mon[427]: 2010/12/20_21:51:54 ERROR: unpack_resources: Either configure some or disable STONITH with the stonith-enabled option
crm_mon[427]: 2010/12/20_21:51:54 ERROR: unpack_resources: NOTE: Clusters with shared data need STONITH to ensure data integrity
============
Last updated: Mon Dec 20 21:51:54 2010
Stack: openais
Current DC: zazu - partition WITHOUT quorum
Version: 1.0.9-74392a28b7f31d7ddc86689598bd23114f58978b
2 Nodes configured, 2 expected votes
0 Resources configured.
============

Online: [ zazu shenzi ]

Now we will configure a few things:

  • No quorum (because it's a 2-node cluster)
  • No Stonith (Fencing)
  • For stickiness, this is to avoid auto-failback of resources
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> crm
crm(live)# configure
crm(live)configure# property no-quorum-policy=ignore
crm(live)configure# property stonith-enabled=false
crm(live)configure# property default-resource-stickiness=1000
crm(live)configure# commit
crm(live)configure# bye