Xen

Xen is an open-source virtual machine server to be run on Linux. At Maretec we recently took a course on Xen and have installed a quad-core Opteron machine with 20GB RAM and a nearly 2TB RAID 5 storage volume.

Maretec xen admin quick start

Quick check on VM machines, and start them if needed

• Download putty,
• Connect, using putty, to host 192.168.20.125 on port 22 as user maretec; use the admin password.
• Once in, perform the following command to check which machines are running and which are down:

> sudo /usr/sbin/xm list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  2048     2     r-----  20156.6
VMMRTSRV02                                   2  1024     2     -b----  75002.4
VMMRTSRV04                                   3  1024     2     -b----   3830.1
VMMRTSRV05                                   6  1024     2     -b----   2433.5
VMMRTSRV06                                   4  1024     2     -b----   6656.9

• The machines with the second state set to b are running for the amount of time indicated in seconds.
• The machines with the second state set to - aren't running. To start them using the following command for each machine:

> sudo /usr/sbin/xm start VMMRTSRV0[2-6]

Useful stuff to know

How to start a VM? 

> sudo /usr/sbin/xm start VMMRTSRV0[2-6]

How to reboot a VM? 

> sudo /usr/sbin/xm reboot VMMRTSRV0[2-6]

How to shutdown a VM? 

> sudo /usr/sbin/xm shutdown VMMRTSRV0[2-6]

How do I know which sudo commands are available to me? 

> sudo -l

How do I know which commands are available with xm? 

> sudo /usr/sbin/xm list

Maretec Xen server machine

Hardware

• Quad-core Opteron AMD with 20GB ram and 2 TB RAID5 Physical Volume composed by 4x750GB enterprise-graded hard-drives,
• Suse Enterprise Server v10.2 with Xen Hypervisor installed,
• Network address at 192.168.20.125.
• RAID 5 of 1.97TB with no hot-swap disk available.
• Bridging: eth2<->192.168.20.125; eth1<->DMZ; eth0<->LAN;

Maretec Xen domains

VMMRTSRV0[4,5]

a windows server 2003 web-pages server on the DMZ. Domain name is einstein.maretec.ist.utl.pt, IP is 192.168.21.10.

VMMRTSRV0[4,5]

a windows server 2003 database server on the LAN. Domain name is copernico.maretec.ist.utl.pt, IP is 192.168.20.10.

VMMRTSRV06

A dedicated OpenDAP/Thredds server on the DMZ. Domain name is opendap.mohid.com, IP is 192.168.21.20 and VNC console access is 192.168.20.125:3.

Accessing via VNC

• Install <goto>TightVNC client</goto>.
• Then access to 192.168.20.125:? to have console access. You need to determine which port(?) is allocated to the VM. You can test values ranging from [1-9], or you can check the xen_config directory in the 192.168.20.125 machine (access it with ssh or putty).

External references

• Xen homepage