On 05/23/11 23:34, Lars Ellenberg wrote: > 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 ;-) > > Just out of curiosity: why the recommendation against serial communication (as backup medium for instance) in non-haresources clusters?
thx, B. _______________________________________________ Linux-HA mailing list Linux-HA@lists.linux-ha.org http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
