[Beowulf] pdsh question
ashley at pittman.co.uk
Tue May 11 13:17:40 PDT 2010
On 11 May 2010, at 19:20, Prentice Bisbal wrote:
> Since so many of you use and recommend pdsh, I have a few questions for
> 1. Do you build and RPM from the .spec file, which doesn't support
> genders, or do you configure/compile yourself?
I build it myself. From the top of my head the options I use are --with-ssh --without-rsh. Last time i built it if both were built the default was to prefer rsh over ssh which should probably be changed at some point.
> 2. If not using genders, what is the syntax of the /etc/machines file? I
> assume it's the same as the gender file, but that's just a hunch.
It's just a flat list of hosts, one per line, although I believe it can take host-specs as well. e.g compute[0-1023]
> 3. Are there any advantages/disadvantages to using machines over genders?
Genders is much more flexible, machines is easier to configure.
Two more things of note, "dshbak -c" is worth knowing about, pipe the output of pdsh into this and it'll sort the output by hostname and compress hosts with identical output into a single report.
The other really useful aspect of pdsh is the "-R exec" option, instead of running the command on a remote node it runs the command locally but replaces %h with the hostname. One trivial example is "pdsh -a -R exec grep %h /var/log/messages | dskbak -c" but once you get used to it you can use it for much more advanced commands, earlier on today I ran "pdsh -w [0-25] -R exec tune2fs -O extents /dev/mapper/ost_%h" to re-tune all the devices in a lustre filesystem.
Ashley Pittman, Bath, UK.
Padb - A parallel job inspection tool for cluster computing
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