The Triora Group

As I noted in my previous entry I was finally configured to start creating Virtual Machines (VM).  But first I wanted to do some background checking on what I had actually installed.

On the Dell I found a lean version of Linux.  A uname -a command returned this:

Linux hostname 2.6.18-8.1.15.1.16.el5xen #1 SMP Fri Aug 1 18:27:30 EDT 2008 i686 i686 i386 GNU/Linux

My file systems consisted of the following:

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2             3.0G  807M  2.0G  29% /
/dev/sda3             1.4T  176G  1.2T  13% /OVS
/dev/sda1              99M   36M   59M  38% /boot
tmpfs                 293M     0  293M   0% /dev/shm

The /OVS filesystem was where the VM configurations and files would be stored.  Over in the /OVS filesystem I had the following directories created.

• local
• iso_pool
• running_pool – contains subdirectories for each VM
• seed_pool – contains VM templates that have been imported via the Oracle Virtual Machine Manager gui
• publish_pool
• remote
• templates
• sharedDisk
• tmp

Using OVM Manager creates or copies files to directories as needed.  I haven’t reached the point where every directory has a file in it yet since I haven’t exercised all of the features of OVM Manager yet.  I do have files in seed_pool, running_pool, sharedDisk, and templates.

running_pool, which sounds like a good american indian name, is the directory where each VM is defined as a sub-directory.  The subdirectories are names 999_hostname where 999 is a sequence id along with the hostname you selected during the create VM process.  Inside that sub-directory you will find the following files.

• README – Just a text file with a brief message.
• System.img – an image file containing the filesystems for root, boot, etc.  (about 3GB in size)
• vm.cfg – a text file with the configuration information about the Virtual Machine
• vm.cfg.orig – an original  copy of vm.cfg

Here’s what is typically in the vm.cfg file with a barebones VM create.  It mentions the System Image file, CDRom, maximum memory, startup memory and the two physical ethernet adapters along with their virtual interfaces.  It also shows that this VM will use 2 virtual cpu cores when running (vcpus).  I’ve replaced my actual hostname with hostname below.

acpi = 1
apic = 1
builder = ‘hvm’
device_model = ‘/usr/lib/xen/bin/qemu-dm’
disk = ['file:/OVS/running_pool/hostname/System.img,hda,w',
',hdc:cdrom,r',
]
disk_other_config = []
kernel = ‘/usr/lib/xen/boot/hvmloader’
keymap = ‘en-us’
maxmem = ‘8192′
memory = ‘4096′
name = ‘hostname‘
on_crash = ‘restart’
on_reboot = ‘restart’
pae = 1
serial = ‘pty’
timer_mode = ‘2′
uuid = ‘c20ee3f5-08cc-b38b-c50d-368f04709d86′
vcpus = 2
vif = [’bridge=xenbr0,mac=00:16:3E:03:87:08,type=netfront’,
‘bridge=xenbr1,mac=00:16:3E:1E:06:5A,type=netfront’,

Using the OVM Manager I can added/delete new Virtual Disks, modify memory settings, and make changes to the Virtual Ethernet adapters.  As I’ve added new disks to existing Virtual Machines I get an additional img file in the directory and an additional reference to it in the vm.cfg file.

Here’s a sample screen shot of OVM Manager showing the four VM’s I’ve defined.

At the top you can see the major menu entries for managing VM’s, Resources, Servers, Server Pools and Administration.

Administration is where you setup the users who can manage this console.

Server Pools must be defined and is a grouping of physical servers.

Servers are all physical servers defined.  In my case there is one, the Dell 2950.

Resources is where you can manage VM Images, Templates (which you can download from Oracle), ISO files and Shared Disks.

On the Virtual Machines screen shown you can startup, shutdown, configure and view the console of a specific virtual machine.  There are other options including deleting a VM under the “More Actions” drop down.

One of the first problems I had was that this VM Manager became out-of-sync with reality.  It showed a V M as “Initiating” when it was actually shutdown.  To fix that problem I had to go into the XE database and reset the status of the VM using  standard SQL update and commit commands.  That seemed awkward!

UPDATE! After I figured the solution out on my own I then found a note about it down in the troubleshooting section of the documentation for the VM Manager.

SQL> update ovs.ovs_vm_img t set t.status=’Powered Off’ where t.img_name like ‘vm_name‘;
SQL> commit;
SQL> quit

Creating new VM’s is simple.  The real question is do you want to create it from a Template, ISO file or existing VM image?

More on that in my next post.

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