Difference between revisions of "Xen"

Revision as of 17:57, 12 January 2010

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 to list installed VMs?: > sudo /usr/sbin/xm list
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 -l

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

VMMRTSRV05: a windows server 2003 web-pages server on the DMZ. Domain name is einstein.maretec.ist.utl.pt, IP is 192.168.21.10 and VNC console access is 192.168.20.125:?.
VMMRTSRV04: 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).

How do I know how much space do I have left free?

Suppose you want to create a new LV (Logical Volume) within the VG (Volume Group) "dados01". Then you want to check how much free PE (Physical Extent) you have. In the example below you can see that we had 1.26 TB allocated (non-free) PE and 720.38 GB free PE.

> sudo /sbin/vgdisplay dados01

 --- Volume group ---
 VG Name               dados01
 System ID
 Format                lvm2
 Metadata Areas        1
 Metadata Sequence No  37
 VG Access             read/write
 VG Status             resizable
 MAX LV                0
 Cur LV                18
 Open LV               9
 Max PV                0
 Cur PV                1
 Act PV                1
 VG Size               1.97 TB
 PE Size               128.00 MB
 Total PE              16123
 Alloc PE / Size       10360 / 1.26 TB
 Free  PE / Size       5763 / 720.38 GB
 VG UUID               Ng5URl-392K-nEvS-wn4k-D1KG-dmbb-QT1VHR

External references

Xen homepage

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Difference between revisions of "Xen" - MohidWiki

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