On Mon, May 23, 2011 at 01:59:23PM -0700, Hai Tao wrote: > > this might not be too close to HA, but I am not sure if someone has seem this > before: > > I use a serial cable between two nodes, and I am testing the heartbeat with : > > > server2$ cat < /dev/ttyS0 > server1$ echo hello > /dev/ttyS0 > > instead of receiving "hello" on server2, I see some hashed code there. > > Does someone have an idea why I do not receive the "hello" in clear text?
Mismatch of settings, especially baud, flow control, or similar. If you really want to do this manually, learn about stty. for starters, try, on both nodes, stty -F /dev/ttyS0 and compare the output. Then try stty 115200 cs8 -F /dev/ttyS0 and add whatever else you need to get useful settings. You also need a "null modem cable", usually, not just any serial cable. Note that, in contrast to the "haresources" mode, with Pacemaker, not only small heartbeats are exchanged, but larger stringified XML, occasionally even the whole CIB, inclusive configuration and status sections. Which, with a few resources, even when compressed, can reach an "unexpected" volume. Consider the transfer time of even only 10kByte on a serial port connection. (Yes, that's ~one second, on a fast port!). You want the highest possible stable baud rate, the smallest possible pacemaker configuration, and timeouts that take this into account. In my experience, boxes that have high volume serial port activity can feel very sluggish in all aspects. For non-haresources clusters, we recommend against serial communication paths. We also recommend against haresources clusters, unless that really is all you want and need. So probably just forget about serial communication paths, but use all available physically independend network links, then add an other two ;-) -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
