Thomas Krause wrote:
> I needed a simple tool to power off and restart my clients. So I wrote a
> small utility that can query the power status of clients and remotely
> restart or shutdown them.
This is absolutely useful and I think your implementation could be a
nice start. Thanks for raising this topic again.
After some thought with another interested sysadmin we decided that
probably the best approach to support any kind of power control
mechanism is to define a special tag in cluster.xml (via
si_clusterconfig). The value of this attribute will be used to specify
the command to control the power of any specific group of clients.
For example this could be a group defined by si_clusterconfig to control
IBM e326m servers via BMC and ipmitool:
<group>
<name>cluster1</name>
<image>RHEL5</image>
<override>RHEL5</override>
<node>node001-node100</node>
<power-control>ipmitool -I lan -A NONE -U USERID -H</power-control>
</group>
The <power-control> command above should be expanded by si_power in some
parallel tasks in the form:
ipmitool -I lan -A NONE -U USERID -H node001 power on
ipmitool -I lan -A NONE -U USERID -H node002 power on
...
ipmitool -I lan -A NONE -U USERID -H node100 power on
And maybe a reasonable syntax for si_power should be in this case:
# si_power -n cluster1 power on
The same for "power off", "power status" and "power cycle" and in part
the specific si_power command passed as argument would depend on the
particular syntax of the power control method.
Your implementation (power control via ssh) is a particular case and it
can be expressed in this way:
<group>
<name>cluster2</name>
<image>Ubuntu8.04</image>
<override>Ubuntu8.04</override>
<node>host1-host20</node>
<power-control>ssh -l root</power-control>
</group>
And the si_power syntax would be:
power off:
# si_power -n cluster2 init 0
reboot:
# si_power -n cluster2 init 6
Ok, this is a good example because it needs a different power control
method to power on clients respect to power off and reboot: the WOL (BTW
see this python script
http://gsd.di.uminho.pt/jpo/software/wakeonlan/mini-howto/wolpython.txt).
So, probably a more generic approach would be to differentiate each
single operations inside the <power-control> object. But maybe in this
way the syntax would become too much difficult to read / understand.
Re-writing the previous example (and supposing wol is the command to
turn on clients via WOL):
<group>
<name>cluster2</name>
<image>Ubuntu8.04</image>
<override>Ubuntu8.04</override>
<node>host1-host20</node>
<power-control>
<poweron>wol %H</poweron>
<poweroff>ssh -l root %H init 0</poweroff>
<reboot>ssh -l root %H init 6</reboot>
</power-control>
</group>
The special character %H would be resolved in each single host name by
si_power.
Another possible way could be to implement all the possible (known)
power control methods directly by specific SystemImager commands
(si_power_ipmi, si_power_wol, si_power_ssh, etc.) or by si_power
options, but I don't like this approach, because it's a lot of
development work, it doesn't scale at all, and can lead to many bugs
and errors due to different versions of the particular power control
methods (ipmi, wol, etc.).
In conclusion I would prefer a more generic approach, providing in
SystemImager all the abstract primitives to define all the possible
commands to control the clients' power.
Other ideas, criticisms, appreciations, suggestions, etc. are welcome.
-Andrea
-------------------------------------------------------------------------
This SF.net email is sponsored by the 2008 JavaOne(SM) Conference
Don't miss this year's exciting event. There's still time to save $100.
Use priority code J8TL2D2.
http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone
_______________________________________________
sisuite-users mailing list
sisuite-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/sisuite-users
