Re: [Linux-cluster] RHEL3 Cluster Heart Beat Using Cross Over Cable

[Rick Stevens <ricks nerd com>]

lingu wrote:
> Hi,
>
>  I am running two node active/passive  cluster running  RHEL3 update
> 8 64 bit  OS on Hp Box with external hp storage connected via scsi. My
> cluster was running fine for  last 3 years.But all of a sudden cluster
> service keep on shifting (atleast one time in a day )form one node to
> another.
>
>  After analysed the syslog i found that  due to some network
> fluctuation service was getting shifted.Both the nodes has two NIC
> bonded together and configured with  below ip.
>
> My network details:
>
> 192.168.1.2 --node 1 physical ip  with  class c subnet (bond0 )
> 192.168.1.3 --node 2 physical ip  with class c subnet (bond0 )
> 192.168.1.4  --- floating ip  ( cluster )
>
>  Since it is a very critical and busy server may be due to heavy
> network load  some hear beat signal is getting missed  resulting in
> shifting of service from one node to another.
>
> So i planned to connect crossover cable for heart beat messages, can
> any one guide me  or provide me the link that best explains  how to do
> the same and the changes i have to made in cluster configuration file
> after connecting the crossover cable.

The crossover cable is pretty easy to make and a lot of places have
ones prebuilt.  If you want to make one yourself, you're interested in
the orange pair of wires (normally pins 1 and 2) and the green pair of
wires (normally pins 3 and 6).  The blue and brown pairs don't do
anyting in standard TIA-56B cables.  The wiring diagram is:

	End "A" (std)			End "B" (crossover)
	pin 1		Orange/White	pin 3
	pin 2		Orange		pin 6
	pin 3		Green/White	pin 1
	pin 4		Blue		pin 4
	pin 5		Blue/White	pin 5
	pin 6		Green		pin 2
	pin 7		Brown/White	pin 7
	pin 8		Brown		pin 8

Remember that the pins are numbered from the left, looking at the hole
the cable goes into with the latch on the bottom.  I generally put some
sort of rather blatant mark on any such cable such as a big piece of
tape or coloring the ends with a red marker so it's obvious that the
cable is "special".

To use it, just plug one end of the cable into the cluster NIC of the
first system and the other end into the cluster NIC of the second
system.  You should get link lights at both ends.

As far as any other changes, the only thing that may go a bit weird is
the ARP tables on the systems since you've removed the hub/switch from
the signal path and the ARP table may retain the old HW addresses.  I
don't think that'll be a problem.
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- Rick Stevens, Systems Engineer                      ricks nerd com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
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-                         good with ketchup.                         -
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