heartbeat 設定メモ

heartbeat スタートガイド

今回の構成
Node 1 (linuxha1):   192.168.85.1  (normal 192x net)
                     10.0.0.1 (ハートビート用プライベートネットワーク)
Node 2 (linuxha2):   192.168.85.2
                     10.0.0.2
クラスタ用アドレス：192.168.85.3


まず設定する必要のあるファイルは、/etc/ha.d/ha.cf


watchdog /dev/watchdog

Optional.  The watchdog function provides a way to have a system that is still minimally functioning, but not providing a heartbeat, reboot itself after a minute of being sick.  This could help to avoid a scenario where the machine recovers its heartbeat after being pronounced dead.  If that happened and a disk mount failed over, you could have two nodes mounting a disk simultaneously. If you wish to use this feature, then in addition to this line, you will need to load the "softdog" kernel module and create the actual device file.  To do this, first type "insmod softdog" to load the module. Then, type "grep misc /proc/devices" and note the number it reports (should be 10).  Next, type "cat /proc/misc | grep watchdog" and note that number (should be 130).  Now you can create the device file with that info typing, "mknod /dev/watchdog c 10 130".

bcast eth1

Specifies to use a broadcast heartbeat over the eth1 interface (replace with eth0, eth2, or whatever you use).

keepalive 2

Sets the time between heartbeats to 2 seconds.

warntime 10

Time in seconds before issuing a "late heartbeat" warning in the logs.

deadtime 30

Node is pronounced dead after 30 seconds.

initdead 120

With some configurations, the network takes some time to start working after a reboot.   This is a separate "deadtime" to handle that case.  It should be at least twice the normal deadtime.

hopfudge 1

Optional.  For ring topologies, number of hops allowed in addition to the number of nodes in the cluster.

baud 19200

Speed at which to run the serial line (bps).

udpport 694

Use port number 694 for bcast or ucast communication. This is the default, and the official IANA registered port number.

auto_failback on

Required.  For those familiar with Tru64 Unix, heartbeat acts as if in "favored member" mode.  The master listed in the haresources file holds all the resources until a failover, at which time the slave takes over.  When auto_failback is set to on once the master comes back online, it will take everything back from the slave.  When set to off this option will prevent the master node from re-acquiring cluster resources after a failover. This option is similar to to the obsolete nice_failback option. If you want to upgrade from a cluster which had nice_failback set off, to this or later versions, special considerations apply in order to want to avoid requiring a flash cut. Please see the FAQ for details on how to deal with this situation.

node linuxha1.linux-ha.org

Mandatory.  Hostname of machine in cluster as described by `uname -n`.

node linuxha2.linux-ha.org

Mandatory.  Hostname of machine in cluster as described by `uname -n`.

respawn  userid  cmd

Optional:  Lists a command to be spawned  and monitored.  Eg:  To spawn ccm daemons the following line has to be added:

        respawn hacluster /usr/lib/heartbeat/ccm
Informs heartbeat to spawn the command with the credentials of that of userid (hacluster, in this example) and monitors the health of the process, respawning it if dead.  For ipfail, the line would be:
          respawn hacluster /usr/lib/heartbeat/ipfail
NOTE: If the process dies with exit code 100, the process is not respawned.

ping    ping1.linux-ha.org  ping2.linux-ha.org ....

Optional: Specify ping nodes.  These nodes are not considered as cluster nodes.  They are used to check  network connectivity for modules like ipfail.

ping_group    name  ping1.linux-ha.org  ping2.linux-ha.org ....

Optional: Specify a group ping nodes.  These are the similar to ping nodes, but if any node in a group is available then the group is considered available. The group name can be any string and is used to uniquely identify the group. Each group must appear on a separate line. Like ping nodes the group is not considered to be a cluster node. They appear to be the same as ping nodes and are used to check  network connectivity for modules like ipfail.

続いては /etc/ha.d/haresoureces の設定。このファイルは両方のノードで同じである必要がある。

例えば apache と samba をHAで構成したい場合

linuxha1 192.168.85.3 httpd smb

と設定する。このIPアドレスはクラスタのアドレスで、haresourece ファイルの中にのみ記述する。こうすることで、このアドレスでapacheとsmbのサービスが起動する。
httpd と smb は、当然ながら /etc/rc.d/init.d にスクリプトが存在する必要がある。
もしくは、 /etc/ha.d/resource.d でも構わない。
ちなみに、ネットマスクはIPアドレスのクラスを元に勝手にネットマスクが設定されるが、自分で設定したい場合は、192.168.85.3/24 とかで設定する。

Configuring ipfail
The ipfail plugin attempts to provide detection of network failures, and then intelligently react, directing the cluster to failover resources as necessary. In order to accomplish this goal, it uses ping nodes or ping groups which work as "dumb" third parties in the cluster. Provided both HA nodes can communicate with each other, ipfail can reliably detect when one of their network links has become unusable, and compensate.

To configure ipfail, the following steps must be performed.

1. Select good ping node candidates.
   It is essential that good strategic ping nodes be selected. The better your choices, the stronger your HA cluster becomes. Choosing solid network devices like switches and routers is a good idea. Do not choose either of the members of the HA cluster. Nor should you select someone's workstation. It is also important to select ping nodes that reflect the connectivity of your HA nodes. If you wish to monitor the connectivity of two interfaces, it is wise to select a ping node for each interface, that is reachable exclusively from said interface. Consult ipfail-diagram.pdf for a graphical representation of this idea.
   
2. Set auto_failback to on or off.
   ipfail will only operate if heartbeat has been configured to something other than legacy In ha.cf, set the auto_failback option to "on" or "off" like so:

   auto_failback on

   or

   auto_failback off

3. Configure your ha.cf to start ipfail.
   Add a line like the following to ha.cf (assuming your compile PREFIX is /usr)

   respawn hacluster /usr/lib/heartbeat/ipfail

4. Add the ping nodes to ha.cf.
   The ping nodes can be added to the cluster by using a line like the following:

   ping pnode1 pnode2 pnodeN

   Simply replace pnode1, pnode2, ... pnodeN with the IP addresses of your ping nodes.

Ensure that the above configuration directives are added to the ha.cf on both members of the cluster, and that they are identical.

NOTE: You will want to check on the availability of the ping nodes prior to using them. If you cannot ping them from both of the HA nodes, they are useless.

Selecting an Interface

One important aspect of configuring the haresources file for a machine which has multiple ethernet interfaces is to know how heartbeat selects which interface will wind up supporting the service addresses that are configured in haresources.  After all, no interface was specified in the haresources file. Heartbeat decides which interface will be used by looking at the routing table.  It tries to select the lowest cost route to the IP address to be taken over.  In the case of a tie, it chooses the first route found.  For most configurations this means the default route will be least preferred.
If you don't specify a netmask for the IP address in the haresources file, the netmask associated with the selected route will be used. Simmilarly, if an interface is not specivied, then the virtual ip address will be added to the interface associated with the selected route. If the broadcast address is omitted then the hightest address in the subnet is used.
 
Configuring Authkeys
The third file to configure determines your authentication keys.  There are three types of authentication methods available:  crc, md5, and sha1.  "Well, which should I use?", you ask.  Since this document is called "Getting Started", we'll keep it simple......
If your heartbeat runs over a secure network, such as the crossover cable in our example, you'll want to use crc.  This is the cheapest method from a resources perspective.  If the network is insecure, but you're either not very paranoid or concerned about minimizing CPU resources, use md5.  Finally, if you want the best authentication without regard for CPU resources, use sha1.  It's the hardest to crack.
The format of the file is as follows:
auth <number>
<number> <authmethod> [<authkey>]
SO, for sha1, a sample /etc/ha.d/authkeys could be:
auth 1
1 sha1 key-for-sha1-any-text-you-want
For md5, you could use the same as the above, but replace "sha1" with "md5".
Finally, for crc, a sample might be:
auth 2
2 crc
Whatever index you put after the keyword auth must be found below in the keys listed in the file. If you put "auth 4", then there must be an "4 signaturetype" line in the list below.
Make sure its permissions are safe, like 600.  And "any text you want" is not quite right.  There's a limit to the number of characters you can use.
That's it!

Starting and testing heartbeat

From Red Hat, or other distributions which use /etc/init.d startup files, simply type /etc/init.d/heartbeat start on both nodes.  I would recommend starting on the system master (in our example linuxha1) first. If you want heartbeat to run on startup, what to do will differ on your distribution.  You may need to place links to the startup script in the appropriate init level directories, but the RPM versions will do this for you.  I have heartbeat start at its default sequential priority (75, which means it starts after services 74 and lower and before services with priority 76-99), end at its default sequential priority (05), and only care about the 0(halt), 6(reboot), 3(text-only), 5(X) run levels.
So, if I had to do it by hand, I'd need to type in the following (as root, of course):
    cd /etc/rc.d/rc0.d ; ln -s ../init.d/heartbeat K05heartbeat
    cd /etc/rc.d/rc3.d ; ln -s ../init.d/heartbeat S75heartbeat
    cd /etc/rc.d/rc5.d ; ln -s ../init.d/heartbeat S75heartbeat
    cd /etc/rc.d/rc6.d ; ln -s ../init.d/heartbeat K05heartbeat
The last time I ran slackware, there was no /etc/rc.d/init.d directory (may have changed by now) and to do the same thing, I would have placed in /etc/rc.d/rc.local:
    /etc/ha.d/heartbeat start
***This assumes you copy the file ha.rc to /etc/ha.d/heartbeat.  If you can't find /etc/rc.d/init.d with your distribution and you're unsure of how processes start, you can use the rc.local method.  But you're on your own for shutdown, I just don't remember...
Note:  If you use the watchdog function, you'll need to load its module at bootup as well.  You can put the following command at the bottom of the /etc/rc.d/rc.sysinit file:
    /sbin/insmod softdog
For the rc.local method, just put the same line right above where you start heartbeat.
 
Once you've started heartbeat, take a peek at your log file (default is /var/log/ha-log) before testing it.  If all is peachy, the service owner's log (linuxha1 in our example) should look something like this:
heartbeat: 2003/02/10_13:52:22 info: Neither logfile nor logfacility found.
heartbeat: 2003/02/10_13:52:22 info: Logging defaulting to /var/log/ha-log
heartbeat: 2003/02/10_13:52:22 info: **************************
heartbeat: 2003/02/10_13:52:22 info: Configuration validated. Starting heartbeat 0.4.9f
heartbeat: 2003/02/10_13:52:22 info: nice_failback is in effect.
heartbeat: 2003/02/10_13:52:22 info: heartbeat: version 0.4.9f
heartbeat: 2003/02/10_13:52:22 info: Heartbeat generation: 17
heartbeat: 2003/02/10_13:52:22 info: Starting serial heartbeat on tty /dev/ttyS0 (19200 baud)
heartbeat: 2003/02/10_13:52:22 info: UDP Broadcast heartbeat started on port 694 (694) interface eth1
heartbeat: 2003/02/10_13:52:23 info: pid 28140 locked in memory.
heartbeat: 2003/02/10_13:52:23 info: pid 28137 locked in memory.
heartbeat: 2003/02/10_13:52:23 info: pid 28139 locked in memory.
heartbeat: 2003/02/10_13:52:23 notice: Using watchdog device: /dev/watchdog
heartbeat: 2003/02/10_13:52:23 info: pid 28141 locked in memory.
heartbeat: 2003/02/10_13:52:23 info: Local status now set to: 'up'
heartbeat: 2003/02/10_13:52:23 info: pid 28138 locked in memory.
heartbeat: 2003/02/10_13:52:23 info: pid 28134 locked in memory.
heartbeat: 2003/02/10_13:52:25 info: Link linuxha1.linux-ha.org:eth1 up.
heartbeat: 2003/02/10_13:53:23 WARN: node linuxha2.linux-ha.org: is dead
heartbeat: 2003/02/10_13:53:23 info: Dead node linuxha2.linux-ha.org held no resources.
heartbeat: 2003/02/10_13:53:23 info: Resources being acquired from linuxha2.linux-ha.org.
heartbeat: 2003/02/10_13:53:23 info: Local status now set to: 'active'
heartbeat: 2003/02/10_13:53:23 info: Running /etc/ha.d/rc.d/status status
heartbeat: 2003/02/10_13:53:23 info: /usr/lib/heartbeat/mach_down: nice_failback: acquiring foreign resources
heartbeat: 2003/02/10_13:53:23 info: mach_down takeover complete.
heartbeat: 2003/02/10_13:53:23 info: mach_down takeover complete for node linuxha2.linux-ha.org.
heartbeat: 2003/02/10_13:53:23 info: Acquiring resource group: linuxha1.linux-ha.org 192.168.85.3 datadisk::drbd0 datadisk::drbd1 mirror
heartbeat: 2003/02/10_13:53:23 info: Running /etc/ha.d/resource.d/IPaddr 192.168.85.3 start
heartbeat: 2003/02/10_13:53:23 info: /sbin/ifconfig eth0:0 192.168.85.3 netmask 255.255.255.0  broadcast 192.168.85.255
heartbeat: 2003/02/10_13:53:23 info: Sending Gratuitous Arp for 192.168.85.3 on eth0:0 [eth0]
heartbeat: 2003/02/10_13:53:23 /usr/lib/heartbeat/send_arp eth0 192.168.85.3 00304823BD48 192.168.85.3 ffffffffffff
heartbeat: 2003/02/10_13:53:24 info: Running /etc/ha.d/resource.d/datadisk drbd0 start
heartbeat: 2003/02/10_13:53:24 info: Running /etc/ha.d/resource.d/datadisk drbd1 start
heartbeat: 2003/02/10_13:53:25 info: Running /etc/ha.d/resource.d/mirror  start
heartbeat: 2003/02/10_13:53:25 /usr/lib/heartbeat/send_arp eth0 192.168.85.3 00304823BD48 192.168.85.3 ffffffffffff
heartbeat: 2003/02/10_13:53:26 info: Resource acquisition completed.
heartbeat: 2003/02/10_13:53:28 /usr/lib/heartbeat/send_arp eth0 192.168.85.3 00304823BD48 192.168.85.3 ffffffffffff
heartbeat: 2003/02/10_13:53:30 /usr/lib/heartbeat/send_arp eth0 192.168.85.3 00304823BD48 192.168.85.3 ffffffffffff
heartbeat: 2003/02/10_13:53:32 /usr/lib/heartbeat/send_arp eth0 192.168.85.3 00304823BD48 192.168.85.3 ffffffffffff
heartbeat: 2003/02/10_13:53:33 info: Local Resource acquisition completed. (none)
heartbeat: 2003/02/10_13:53:33 info: local resource transition completed.
heartbeat: 2003/02/10_13:56:30 info: Link linuxha2.linux-ha.org:eth1 up.
heartbeat: 2003/02/10_13:56:30 info: Status update for node linuxha2.linux-ha.org: status up
heartbeat: 2003/02/10_13:56:30 info: Running /etc/ha.d/rc.d/status status
heartbeat: 2003/02/10_13:56:30 info: Status update for node linuxha2.linux-ha.org: status active
heartbeat: 2003/02/10_13:56:30 info: remote resource transition completed.
heartbeat: 2003/02/10_13:56:30 info: Running /etc/ha.d/rc.d/status status
heartbeat: 2003/02/10_13:56:31 info: Link linuxha2.linux-ha.org:/dev/ttyS0 up.
NOTE:  Your log may differ depending on when you started heartbeat on linuxha2!!!  I started heartbeat on the linuxha2 @13:56:30...

---

OK, now try to ping your cluster's IP (192.168.85.3 in the example). If this works, ssh to it and verify you're on linuxha1.
Next, make sure your services are tied to the .3 address.  Bring up netscape and type in 192.168.85.3 for the URL.  For Samba, try to map the drive "\\192.168.85.3\test"  assuming you set up a share called "test".  See Samba docs to get that going.  As an aside, however, you'll want to use the "netbios name" parameter to have your Samba share listed under the cluster name and not the hostname of your cluster member!
NOTE: If you can't bring up the service IP address and you get ha-log entries similar to this:

        SIOCSIFADDR: No such device
        SIOCSIFFLAGS: No such device
        SIOCSIFNETMASK: No such device
        SIOCSIFBRDADDR: No such device
        SIOCSIFFLAGS: No such device
        SIOCADDRT: No such device

It may mean that you need to enable IP aliasing in your kernel build.  Check /usr/src/linux/.config for "CONFIG_IP_ALIAS=y" if you don't have it, you'll have the line "CONFIG_IP_ALIAS is not set".  Rebuild your kernel with IP aliasing enabled.

If this all works, you've got availability.  Now let's see if we have High Availability :-) Take down linuxha1.  Kill power, kill heartbeat, whatever you have the stomach for, but don't just yank both the serial and eth1 heartbeat cables.  If you do that, you'll have services running on both nodes and when you re-connect the heartbeat, a bit of chaos....
Now ping the cluster IP. Approximately 5-10 seconds later it should start responding again. Telnet again and verify you're on linuxha2.  If it happens but takes more like 30 seconds, something is wrong.
If you get this far, it's probably working, but you should probably check all your heartbeats, too.
First, check your serial heartbeat.  Unplug the crossover cable from your eth1 NIC that you're using for your bcast heartbeat.  Wait about 10 seconds.
Now, look at /var/log/ha-log on linuxha2 and make sure there's no line like this:
    1999/08/16_12:40:58 node linuxha1.linux-ha.org: is dead
If you get that, your serial heartbeat isn't working and your second node is taking over.  To avoid any problems, shut down heartbeat on the first node, then test your null modem cable.  Run the above serial tests again.
If your log is clean, great.  Re-connect the crossover cable.  Once that's done, disconnect the serial cable, wait 10 seconds and check the linuxha2 log again.
If it's clean, congrats!  If not, you can check /var/log/ha-log and /var/log/ha-debug for more clues.