Linux Server Details

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====== Manage_XEND ======

===== Managing Xen Virtual Machines =====
Xend can only be managed on dom0, as it has only exlusive access to the hardware. As a result, any temperature or SMART/Disk Monitoring must be done here also.

The basic commands are:
 xm list
 xm top

To get a list of all the XEND control options type:
 xm


==== To RESTART XEND when it crashed etc. ====
This is extreme - and caused the Virtual Machine in question to remain "dying".
 /etc/init.d/xend restart  <nowiki>//</nowiki>didnt work
 <nowiki>//</nowiki>do this ->
 /etc/init.d/xend stop
 killall xenstored xenconsoled
 rm -rf /var/lib/xenstored/*
 /etc/init.d/xend start
 netstat -ltnp  <nowiki>//</nowiki>make sure there is nothing on ports 8000, 8001, 8002, or 8005
 kill any above processes if there are and ->
 /etc/init.d/xend start <nowiki>//</nowiki>this will get xend up and running. The virtual machines may need taking care of

==== XEN LIST TOP Codes ====
 xm top
http://www.die.net/doc/linux/man/man1/xm.1.html

==== Limit CPU of a VM ====
So the need arised to limit the CPU usage by a particular VM which was chewing up 100% CPU of 1 core by running a heavy computational program for 10+ days.
 thunder:~# xm sched-credit -d vm05-name
 {'cap': 0, 'weight': 256}
 thunder:~# xm sched-credit -d vm05-name -c 20   #20 is 20% of 1 physical cpu. Default is 0.
 thunder:~# xm sched-credit -d vm05-name
 {'cap': 20, 'weight': 256}
 
 xm top
 #  Domain-0 -----r     	   410753    0.4 
 #vm05-name ------                 855770   19.9 
 (previously the vm was using 100)

http://wiki.xensource.com/xenwiki/CreditScheduler
Simple :) Munin graphs look a lot better now.




-- More info at http://lists.xensource.com/archives/html/xen-tools/2005-09/msg00011.html <br>
http://lists.xensource.com/archives/html/xen-users/2006-05/msg00397.html