HA Agent on ESX-HOST in cluster CLUSTER-NAME has an error

If you came across this error message when configuring HA:
"HA Agent on ESX-HOST in cluster CLUSTER-NAME has an error"

First thing you will need to check is your name resolution, which is your DNS.

Try to PING each other from the ESX. If you able to do so, the next thing you probably need to check is the /etc/hosts and /etc/resolv.conf files

Especially when you have change the service console ip, the ip in /etc/hosts file most probably still point to the old ip, also the host name is case sensitive.

VMWare - HA

HA prerequisites:

• All hosts in an HA cluster must have access to the same shared storage locations used byall virtual machines on the cluster. This includes any fibre channel, iSCSI, and NFS datastores used by virtual machines.
• All hosts in an HA cluster should have an identical virtual networking configuration. If
  a new switch is added to one host, the same new switch should be added to all hosts in
  the cluster.
• All hosts in an HA cluster must resolve the other hosts using DNS names.
  

VMWare - Edit .vmx file

You can edit your .vmx file if your .vmdk folder path changed. Here where your .vmx file on ESX.

VMWare VMotion

Each of the ESX Server hosts that are involved in VMotion must meet the following
requirements:

• Shared VMFS storage for the virtual machines files
• A gigabit network card with a VMkernel port defined and enabled for VMotion on each host
  

HP c7000 Blade System

Our company just bought a HP c7000 Blade System recently, no doubts I have fun configuring it this few weeks.

Front view 1

Front view 2

Rear view 1

Rear view 2

Rear view 3

Switches

ESX CLI:

• esxcfg-vswitch -a vSwitch1 -> This create a new vSwitch1
• esxcfg-vswitch -L vmnic1 vSwitch1 -> This will link my second physical network interface (vmnic1) to vSwitch1
• esxfg-vswitch -U vmnic1 vSwitch1 -> This will unlink NIC to vSwitch
• esxcfg-vswitch -A "Service Console" vSwitch0 -> This will create a new port group named Service Console.
• esxfg-vswitch -A "VMtion" vSwitch1 -> This will create a new port group named VMotion and associate it to vSwicth1.
• esxcfg-vswif -a vswif0 -p "Service Console" -a 192.168.1.2 -n 255.255.255.0 -b 192.168.1.255 -> This will create new L3 interface which is linked to SC port group with an static IP. ESX server will generate new L2 mac address and assign this to the vswif2 interface.
• esxcfg-vmknic -a -i 10.10.0.5 -n 255.255.255.0 VMotion -> This will assign an IP and subnet mask to the VMotion port group.

Below is the steps to
-- Create a new vSwitch named vSwitch1
-- Associate a physical NIC, in this case vmnic1 to the vSwitch1
-- Create a new Port Group under vSwitch1
-- Create a new NIC under vSwitch1 and assign it an IP and subnet

Changing the DNS server settings

To change the DNS server settings, update the nameserver IPs and search domain the /etc/resolv.conf file.

VMWare - Resize VMFS block size

You are experiencing these issues:

Creating a virtual disk larger than a certain size fails with these errors:

• In the ESX host command line:
  
  Failed to create virtual disk: There is not enough space on the file system for the selected operation.
  
• In the Virtual Infrastructure (VI) Client for ESX 3.0 with VirtualCenter 2.0:
• In the VI Client for ESX 3.5 with Virtual Center 2.5 and in vSphere 4.0 with vCenter:

VMFS Size Limitations

There is no way to change the block size of a VMFS datastore once it is created. The data store must be reformatted with the required block size.

Block Size	Largest virtual disk on VMFS-2	Largest virtual disk on VMFS-3
1MB	456GB	256GB
2MB	912GB	512GB
4MB	1.78TB	1TB
8MB	3.56TB	2TB
16MB	7.18TB	Invalid block size
32MB	14.25TB	Invalid block size
64MB	28.50TB	Invalid block size

With a block size of 1MB, every file that is created uses at least 1MB of space on the storage, regardless of its actual size. With an 8MB block size, a 1KB file still occupies 8MB of space. The unused space in that block is wasted. The larger block size is only required when a file is so large that it requires an extended addressing space. Being aware of the intended use helps with your planning and efficient use of space on the data store.

To create a resized datastore:

Note: All data on a VMFS volume is lost when the data store is recreated. Backup all data before proceeding.

• In the VI Client / vSphere connected to VirtualCenter / vCenter:
  
  
  1. Remove the datastore from one of the ESX hosts.
  2. Rescan for VMFS volumes from the other hosts that can see the datastore.
  3. Create the new datastore on one of the hosts.
  4. Rescan for VMFS volumes from all other hosts that can see the datastore.
     
     
• From the ESX console:
  
  
  1. Use vmkfstools to create a new volume over the existing one.
  2. Rescan from all other ESX hosts with the command vmkfstools -V . For syntax on creating the VMFS volume, please consult the appropriate document listed below.

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003565

Processor Affinity

Is two better than one? Not necessarily, if your dual-core processor runs at less-than-effective efficiency with older programs. Here's how to optimize your processor settings to allow Windows XP Professional to run more smoothly by switching to just one core when running certain applications.

If you have a dual-core processor, you may discover that certain older applications that ran fine on systems with a single core CPU have problems running with two cores. For example, your application may suddenly begin maxing out the CPU usage at 100 percent, appearing to lock up. Windows XP Professional's Processor Affinity setting allows you to work around such problems by configuring older applications to use only one of the cores. Here's how to set it up:

1.Access Task Manager.
2.Choose the Processes tab.
3.Right-click the process associated with the problem application.
4.Select the Set Affinity command. (If you don't have a dual-core system, you won't see the Set Affinity command.)
5.From the Processor Affinity dialog box, clear one of the CPU check boxes.

You could perform this manual operation every time you run the application, but the THG Task Assignment Manager (available for download from Tom's Hardware) allows you to create profiles that automatically assign applications to a specific CPU every time you run them.

Note: This tip applies only to Windows XP Professional.

http://yahoo-tej.blogspot.com/2007/10/automatically-set-processor-affinity-in.html