HACMP topology & usefull commands

HACMP topology & usefull commands
Hacmp can be configured in 3 ways.

1. Rotating
2. Cascading
3. Mutual Failover

The cascading and rotating resource groups are the “classic”, pre-HA 5.1 types. The new “custom” type of resource group has been introduced in HA 5.1 onwards.


Cascading resource group:
Upon node failure, a cascading resource group falls over to the available node with the next priority in the node priority list.
Upon node reintegration into the cluster, a cascading resource group falls back to its home node by default.

Cascading without fallback
Thisoption, this means whenever a primary node fails, the package will failover to the next available node in the list and when the primary node comes online then the package will not fallback automatically. We need to move package to its home node at a convenient time.

Rotating resource group:
This is almost similar to Cascading without fallback, whenever package failover to the standby nodes it will never fallback to the primary node automatically, we need to move it manually at our convenience.

Mutual takeover:
Mutual takeover option, which means both the nodes in this type are active-active mode. Whenever fail over happens the package on the failed node will move to the other active node and will run with already existing package. Once the failed node comes online we can move the package manually to that node.

Useful HACMP commands

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.
lsattr -El inet0 and netstat -nr. The lsattr command will show you the current default

Now, delete the default gateway like this:
lsattr -El inet0 | awk '$2 ~ /hopcount/ { print $2 }' | read GW
chdev -l inet0 -a delroute=${GW}

Specifying the default gateway on a specific interface in HACMP
Specifying the default gateway on a specific interface

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 and netstat -nr. The lsattr command will show you the current default gateway route and the netstat command will show you the interface it is configured on. You can also check the ODM: odmget -q"attribute=route" CuAt.

Now, delete the default gateway like this:
lsattr -El inet0 | awk '$2 ~ /hopcount/ { print $2 }' | read GW
chdev -l inet0 -a delroute=${GW}

If you would now use the route command to specifiy the default gateway on a specific interface, like this:
route add 0 [ip address of default gateway: xxx.xxx.xxx.254] -if enX
You will have a working entry for the default gateway. But... the route command does not change anything in the ODM. As soon as your system reboots; the default gateway is gone again. Not a good idea.

A better solution is to use the chdev command:
chdev -l inet0 -a addroute=net,-hopcount,0,,0,[ip address of default gateway]
This will set the default gateway to the first interface available.

To specify the interface use:
chdev -l inet0 -a addroute=net,-hopcount,0,if,enX,,0,[ip address of default gateway]
Substitute the correct interface for enX in the command above.

If you previously used the route add command, and after that you use chdev to enter the default gateway, then this will fail. You have to delete it first by using route delete 0, and then give the chdev command.

Afterwards, check with lsattr -El inet0 and odmget -q"attribute=route" CuAt if the new default gateway is properly configured. And ofcourse, try to ping the IP address of the default gateway and some outside address. Now reboot your system and check if the default gateway remains configured on the correct interface. And startup HACMP again!

Steps 1 to 17 to configure HACMP
Steps to configure HACMP:

1. Install the nodes, make sure the redundancy is maintained for power supplies, n/w and
fiber n/ws. Then Install AIX on the nodes.
2. Install all the HACMP filesets except HAview and HATivoli.
Install all the RSCT filesets from the AIX base CD.
Make sure that the AIX, HACMP patches and server code are at the latest level (ideally
recommended).
4. Check for fileset bos.clvm to be present on both the nodes. This is required to make the
VGs enhanced concurrent capable.
5. V.IMP: Reboot both the nodes after installing the HACMP filesets.
6. Configure shared storage on both the nodes. Also in case of a disk heartbeat, assign a
1GB shared storage LUN on both nodes.
7. Create the required VGs only on the first node. The VGs can be either normal VGs or
Enhanced concurrent VGs. Assign particular major number to each VGs while creating
the VGs. Record the major no. information.
To check the Majar no. use the command:
ls –lrt /dev grep
Mount automatically at system restart should be set to NO.
8. Varyon the VGs that was just created.
9. V.IMP: Create log LV on each VG first before creating any new LV. Give a unique
name to logLV.
Destroy the content of logLV by: logform /dev/loglvname
Repeat this step for all VGs that were created.
10. Create all the necessary LVs on each VG.
11. Create all the necessary file systems on each LV created…..you can create mount pts
as per the requirement of the customer,
Mount automatically at system restart should be set to NO.
12. umount all the filesystems and varyoff all the VGs.

13. chvg –an All VGs will be set to do not mount automatically at _---
System restart.
14. Go to node 2 and run cfgmgr –v to import the shared volumes.
15. Import all the VGs on node 2
import with the same major number as assigned on node _use smitty importvg -----
16. Run chvg –an for all VGs on node 2.
17. V.IMP: Identify the boot1, boot2, service ip and persistent ip for both the nodes
and make the entry in the /etc/hosts.