Serial line heartbeat on a K server

[Rui Vilao]

Greetings,

I am currently working on a MC/SG cluster running on
two K servers.
Each server has only two LANIC (10bT and 100bT). The chosen configuration will consist in on active
LANIC (heartbeat + data) and one standby LAN.

In order to improve the cluster configuration I would like
to add serial line heartbeat (I have done this on D
servers). However I don?t know where to connect the cable...

Does anybody know if it is possible?

Thanks in advance for your help,

Kind Regards,

Rui.

[John Palmer]

You can extend the built in MUX on the personality card of the K from 3 ports (console, UPS and modem) to 8 by purchasing a Modem Distribution Panel. This plugs into the 9 pin socket marked 'MDP'.

I have used these on several K servers, they are not expensive.

The other possibility is to use the UPS port.

[Stefan Farrelly]

Youll have to use the 9-pin serial port labelled UPS, and yes, I believe it is possible to use as an SG heartbeat.

[melvyn burnard]

You need to be aware that the serial heartbeat in MC/SG cluster is NOT a full heartbeat. I.e. if you lose both connections on teh lan cards, one of the nodes WILL TOC.
It is there purely to overcome short busy periods during which the network might be too busy to receive the heartbeat in time.
You would be much better off considering adding in a thrid lan card on each node in the long run.

[Rui Vilao]

Thanks a lot for your replies!

John and Stefan, as a first and simplest approach, I would use the UPS 9 pin
port. But when I do a "ioscan -f" I don t find any device file associated to it.
It does t seem to be connected...

Melvyn, I don t see the problem in having only one active and one standby LANIC
plus serial line heartbeat:

If one LAN fails, standby LAN will run (one SPOF is covered).
If then the standby (now active) LAN fails (second SPOF, not covered) the system
will not be able to run.
In the case it TOCs, from the application point of view it will always mean
a package switch...

[John Palmer]

You might not have the device files configured. From memory, I think that it ought to be port 1 on the built-in mux therefore cul0p1, cua0p1 and tty0p1.

If you don't have the device files,
sam
-> peripheral devices
-> terminals and modems

will add them for you.

[Rui Vilao]

Greetings,
Thanks again for your contribution!

When I run:

# ioscan -fnkCtty
Class I H/W Path Driver S/W State H/W Type Description
============================================================
tty 0 10/4/0 mux2 CLAIMED INTERFACE MUX
/dev/diag/mux0 /dev/diag/tty0p7 /dev/tty0p1
/dev/diag/tty0p0 /dev/mux0 /dev/tty0p7
/dev/diag/tty0p1 /dev/tty0p0

In SAM, the description of this HW path is MUX (3 ports).
If I understand well we have:

* one port is connected to the console 9 pin serial port (/dev/tty0p0)
* another to the the UPS 9 pin serial port (/dev/tty0p1)
* and another to the the internal modem port (/dev/tty0p7)

Am I correct?

Thanks in advance for your help,

Best Regards,

Rui.

[John Palmer · Accepted solution]

Yes, you are correct. If you did connect an MDP (see my post above) which has 8 ports then the mux would become 8-port but ports 0 1 and 7 are still used for the original purpose. You could only use ports 2-6 on the MDP