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



Nathan Nobbe wrote:
On Thu, Nov 6, 2008 at 10:38 AM, Rick Stevens <ricks nerd com> wrote:

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.


many modern machines will work w/o a crossover cable.   ive got 2 dell 1650s
running heartbeat / drbd over a direct connection for heartbeat
communication.  i dont need to use a crossover on the 1650s for the direct
connection to work, and those boxes are pretty old by now.  so long story
short, probly worth saving a little hassle and just trying a regular cat-5
cable for the direct connection.

or if its a requirement for you hardware you can pick up a 3 foot crossover
at radio shack, bust buy etc, for less than 10 bucks.

True.  Some NICs have autosense for MDI and MDIX cables (the technical
terms for straight and crossover, respectively), but a lot of them
don't.  Nathan's right, try a regular cable first.  If it doesn't work,
crossovers are available at lots of places quite cheaply.  They often
use red cable (the ones I've bought are red), but there are a lot of
straight cables that use red as well, so I'd still mark MDIX cables
very conspicuously.  A big tag that says "I'M A CROSSOVER" can't hurt!

My diagram above is valid if you really want to "roll your own".  I've
made so damned many CAT5/5e/6 cables in my life (MDI and MDIX both),
that I can do it almost in my sleep.  Ditto with thinnet (10Base-2) and
I'm a past master at putting parasite taps on thicknet (10Base-5)
cables, sticking on the transceivers and snaking that gawdawful AUI
cable down cable stud pockets.  I'm an original DECnet geek!
----------------------------------------------------------------------
- Rick Stevens, Systems Engineer                      ricks nerd com -
- AIM/Skype: therps2        ICQ: 22643734            Yahoo: origrps2 -
-                                                                    -
-      On a scale of 1 to 10 I'd say...  oh, somewhere in there.     -
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