half vs full duplex

[ITSD-ACCS]

Hello,

I have 2 questions :
1) I have MC/SG configured for a 2 node cluster with heartbeat interval set to 1 sec. What if my network colleague is going to replace the hub into switch ? should I do halt the cluster or simple shutdown the server ?

2) Since we are going to use switch instead, how should I check if my lan card are capable of using full duplex ? and what else should I need to configure in the system administration level ?

Thank you so much.

[KapilRaj]

1). During the switch over disable the heart beat through LAN and do it through RS232 serial ports.

2). Most of the switches can negotiate & work in half duplex mode , if the system's enet is half duplex. but some are manual check with your collegue...

All the best for the change

kaps

[Dirk Wiedemann]

If you are not familiar in configuring your lan cards and their possibel options I think the easiest way is using sam.
Run sam, chose "Networking and Communications", then "Network Interface Cards".
Now you get a list of all installed NICs. (note: in a running MC/SG cluster lan cards with a attached packet ip are multiple listet, you can identify them on interface names like "lan1:1". Only the other NIC's without colon# are interesting.)
Highlight the NIC you are looking for and chose "Action/Modify". Sam checks automatically the possibel options for that NIC type and displays them. So, if there is a Option "Duplex Mode" you know that your NIC supportet different modes. You can change the values or leave the window unmodified.
Anyway: most of actual NIC are supporting duplex.

regards
Dirk

[ITSD-ACCS]

Sorry guys, I am not familiar with configuring the NIC. Could someone tell me how to disable the heartbeat ? Should I do nothing on the cluster ?

I have checked with my NIC on SAM, but no "duplex" whatsoever for me to modify. Does that mean my NIC can only support half duplex ?

[Stefan Farrelly · Accepted solution]

To change your lan speed and duplex setting you need to do;

1. ioscan -fknClan

This will list all your lan cards. Under the DRIVER column it shows the driver used, match it to the one in this table under Duplex file(files are in /etc.rc.config.d) and edit it manually - theres documentation in each file on what to do;

Driver Duplex file Description Software
btlan hpbtlanconf
btlan0 hpeisabtconf
btlan1 hpbasetconf
btlan3 hpbase100conf Internal (core) LAN card
btlan4 hpgsc100conf
btlan5 hppci100conf "external" PCI card A5230A
btlan6 hpsppci100conf V-class PCI lan card
gelan hpgelanconf GigaBit card A4926A

Theres been discussion before on wether to set full or half duplex. I think the consensus was half duplex - full duplex doesnt really give any benefit and can only cause more problems.

[Andrew Cowan]

I think the simple answer to 1). is to stop the cluster (not the server), then when the switch has been installed, restart it. This will check that the switch is correctly configured, and should immediately show up any problems.

2). Half or Full duplex should not make any difference so long as the switch can handle it. Most switches have LED's showing the speed/mode they have detected, so you have an instant check there. The most likely source of problems is "auto-negotiate" between different cards and/or the switch. Where possible lock your card(s) at 100FD (or whatever), to avaoid this.

The issue I think that you may have missed, is that if you have a single hub or switch, then you still have a single-point of failure.
In an ideal situation you would have two discreet lan segments going to separate switches (or hubs), therefore the failure of anyone one of these components or segments, will not "hose" the entire cluster.

I hope this helps.

[T G Manikandan]

Just check this link

http://forums.itrc.hp.com/cm/QuestionAnswer/0,,0x8bb179bffde7d4118fef0090279cd0f9,00.html


Thanks