When you want to mount an NFS file system on a node of an HACMP cluster, there are a couple of items you need check, before it will work:

• Make sure the hostname and IP address of the HACMP node are resolvable and provide the correct output, by running:

  # nslookup [hostname]
  # nslookup [ip-address]
  

• The next thing you will want to check on the NFS server, if the node names of your HACMP cluster nodes are correctly added to the /etc/exports file. If they are, run:

  # exportfs -va

• The last, and tricky item you will want to check is, if a service IP label is defined as an IP alias on the same adapter as your nodes hostname, e.g.:

  # netstat -nr
  Routing tables
  Destination   Gateway       Flags  Refs  Use    If  Exp  Groups
  
  Route Tree for Protocol Family 2 (Internet):
  default       10.251.14.1   UG      4    180100 en1  -     -
  10.251.14.0   10.251.14.50  UHSb    0         0 en1  -     -
  10.251.14.50  127.0.0.1     UGHS    3    791253 lo0  -     -
  

  The example above shows you that the default gateway is defined on the en1 interface. The next command shows you where your Service IP label lives:

  # netstat -i
  Name  Mtu   Network   Address         Ipkts   Ierrs Opkts
  en1   1500  link#2    0.2.55.d3.75.77 2587851 0      940024
  en1   1500  10.251.14 node01          2587851 0      940024
  en1   1500  10.251.20 serviceip       2587851 0      940024
  lo0   16896 link#1                    1912870 0     1914185
  lo0   16896 127       loopback        1912870 0     1914185
  lo0   16896 ::1                       1912870 0     1914185
  

  As you can see, the Service IP label (in the example above called "serviceip") is defined on en1. In that case, for NFS to work, you also want to add the "serviceip" to the /etc/exports file on the NFS server and re-run "exportfs -va". And you should also make sure that hostname "serviceip" resolves to an IP address correctly (and of course the IP address resolves to the correct hostname) on both the NFS server and the client.

Issue when trying to bring up a resource group: For example, the hacmp.out log file contains the following:

cl_disk_available[187] cl_fscsilunreset fscsi0 hdiskpower1 false cl_fscsilunreset[124]: openx(/dev/hdiskpower1, O_RDWR, 0, SC_NO_RESERVE): Device busy cl_fscsilunreset[400]: ioctl SCIOLSTART id=0X11000 lun=0X1000000000000 : Invalid argument

• Enter into the SMIT fastpath for HACMP "smitty hacmp".
• Select Extended Configuration.
• Select Extended Resource Configuration.
• Select HACMP Extended Resources Configuration.
• Select Configure Custom Disk Methods.
• Select Add Custom Disk Methods.

      Change/Show Custom Disk Methods

Type or select values in entry fields.
Press Enter AFTER making all desired changes.

                                                 [Entry Fields]
* Disk Type (PdDvLn field from CuDv)             disk/pseudo/power
* New Disk Type                                  [disk/pseudo/power]
* Method to identify ghost disks                 [SCSI3]
* Method to determine if a reserve is held       [SCSI_TUR]
* Method to break reserve [/usr/lpp/EMC/Symmetrix/bin/emcpowerreset]
  Break reserves in parallel                     true
* Method to make the disk available              [MKDEV]

HACMP is capable of using an alternative MAC address in combination with its service address. So, how do you set this MAC address without HACMP, just using the command line? (Could come in handy, in case you wish to configure the service address on a system, without having to start HACMP).

# ifconfig enX down
# ifconfig enX detach
# chdev -l entX -a use_alt_addr=yes
# chdev -l entX -a alt_addr=0x00xxxxxxxxxx
# ifconfig enX xxx.xxx.xxx.xxx
# ifconfig enX up

# ifconfig enX down
# ifconfig enX detach
# chdev -l entX -a use_alt_addr=no
# chdev -l entX -a alt_addr=0x00000000000

In order to keep users and all their related settings and crontab files synchronized, here's a script that you can use to do this for you:

sync.ksh

The standard tool for cluster monitoring is clstat, which comes along with PowerHA SystemMirror/HACMP. Clstat is rather slow with its updates, and sometimes the required clinfo deamon needs restarting in order to get it operational, so this is, well, not perfect. There's a script which is also easy to use. It is written by PowerHA/HACMP guru Alex Abderrazag. This script shows you the correct PowerHA/HACMP status, along with adapter and volume group information. It works fine on HACMP 5.2 through 7.2. You can download it here: qha. This is version 9.06. For the latest version, check www.lpar.co.uk.

This tiny but effective tool accepts the following flags:

•   -n (show network interface info)
•   -N (show interface info and active HBOD)
•   -v (show shared online volume group info)
•   -l (log to /tmp/qha.out)
•   -e (show running events if cluster is unstable)
•   -m (show status of monitor app servers if present)
•   -1 (exit after first iteration)
•   -c (CAA SAN / Disk Comms)

# qha -nev

• ST_INIT: cluster configured and down
• ST_JOINING: node joining the cluster
• ST_VOTING: Inter-node decision state for an event
• ST_RP_RUNNING: cluster running recovery program
• ST_BARRIER: clstrmgr waiting at the barrier statement
• ST_CBARRIER: clstrmgr is exiting recovery program
• ST_UNSTABLE: cluster unstable
• NOT_CONFIGURED: HA installed but not configured
• RP_FAILED: event script failed
• ST_STABLE: cluster services are running with managed resources (stable cluster) or cluster services have been "forced" down with resource groups potentially in the UNMANAGED state (HACMP 5.4 only)

Some user accounts, mostly service accounts, may create a lot of email messages, for example when a lot of commands are run by the cron daemon for a specific user. There are a couple of ways to deal with this:

1. Make sure no unnecesary emails are sent at all

To avoid receiving messages from the cron daemon; one should always redirect the output of commands in crontabs to a file or to /dev/null. Also make sure to redirect STDERR as well:

0 * * * * /path/to/command > /path/to/logfile 2>&1
1 * * * * /path/to/command > /dev/null 2>&1

0 * * * * [ -x /path/to/command ] && /path/to/command > /path/to/logfile 2>&1

0 * * * * echo d1-$(let num="$(echo f|mail|tail -1|awk '{print $2}')-1000";echo $num)|mail >/dev/null

If you wish to enable MAC Address take-over on an HACMP cluster, you need a virtual MAC address. You can do a couple of things to make sure you have a unique MAC Address on your network:

• Use the MAC address of an old system, that you know has been destroyed.
• Buy a new network card, use the MAC address, then destroy this card.
• Use a DEADBEEF address: (0xdeadbeef1234). This is a non-existent hardware vendor. You might run into problems with someone else making up a deadbeef address, so use this option with caution.

HACMP provides events, which can be used to most accurately monitor the cluster status, for example via the Tivoli Enterprise Console. Each change in the cluster status is the result of an HACMP event. Each HACMP event has an accompanying notify method that can be used to handle the kind of notification we want.

Interesting Cluster Events to monitor are:

• node_up
• node_down
• network_up
• network_down
• join_standby
• fail_standby
• swap_adapter
• config_too_long
• event_error

# smitty hacmp
Cluster Configuration
Cluster Resources
Cluster Events
Change/Show Cluster Events

# odmget HACMPevent

• clstat - show cluster state and substate; needs clinfo.
• cldump - SNMP-based tool to show cluster state.
• cldisp - similar to cldump, perl script to show cluster state.
• cltopinfo - list the local view of the cluster topology.
• clshowsrv -a - list the local view of the cluster subsystems.
• clfindres (-s) - locate the resource groups and display status.
• clRGinfo -v - locate the resource groups and display status.
• clcycle - rotate some of the log files.
• cl_ping - a cluster ping program with more arguments.
• clrsh - cluster rsh program that take cluster node names as argument.
• clgetactivenodes - which nodes are active?
• get_local_nodename - what is the name of the local node?
• clconfig - check the HACMP ODM.
• clRGmove - online/offline or move resource groups.
• cldare - sync/fix the cluster.
• cllsgrp - list the resource groups.
• clsnapshotinfo - create a large snapshot of the HACMP configuration.
• cllscf - list the network configuration of an HACMP cluster.
• clshowres - show the resource group configuration.
• cllsif - show network interface information.
• cllsres - show short resource group information.
• lssrc -ls clstrmgrES - list the cluster manager state.
• lssrc -ls topsvcs - show heartbeat information.
• cllsnode - list a node centric overview of the hacmp configuration.

When you're using HACMP, you usually have multiple network adapters installed and thus multiple network interface to handle with. If AIX configured the default gateway on a wrong interface (like on your management interface instead of the boot interface), you might want to change this, so network traffic isn't sent over the management interface. Here's how you can do this:

First, stop HACMP or do a take-over of the resource groups to another node; this will avoid any problems with applications when you start fiddling with the network configuration.

Then open up a virtual terminal window to the host on your HMC. Otherwise you would loose the connection, as soon as you drop the current default gateway.

Now you need to determine where your current default gateway is configured. You can do this by typing:

# lsattr -El inet0
# netstat -nr

# odmget -q"attribute=route" CuAt

# lsattr -El inet0 | awk '$2 ~ /hopcount/ { print $2 }' | read GW
# chdev -l inet0 -a delroute=${GW}

# route add 0 [ip address of default gateway: xxx.xxx.xxx.254] -if enX

# chdev -l inet0 -a addroute=net,-hopcount,0,,0,[ip address of default gateway]

# chdev -l inet0 -a addroute=net,-hopcount,0,if,enX,,0,[ip address of default gateway]

# lsattr -El inet0
# odmget -q"attribute=route" CuAt