XenEnterprise: Capturing an Image and Creating a Tier

Intended for use with Cassatt Active Response V5.0.

This blueprint walks through preparing the XenEnterprise software to run in the Cassatt Active Response environment. If you haven't read Understanding the Cross Virtualization Manager and Understanding Blueprints for Deploying Applications, read those first for background and context.

Prerequisites

	Software requirements: XenEnterprise 3.2: obtain licenses for physical and virtual nodes as directed by the vendor
	Hardware requirements: Additional image host requirements for this blueprint: Local disk must be at least 16 GB At least 1 GB of physical memory Console access Refer to the Xen hardware compatibility list for information about hardware known to work with XenEnterprise and hardware that is problematic with XenEnterprise. If your data center contains servers that are incompatible with XenEnterprise, use custom attributes on compatible servers and this tier to ensure that Cassatt Active Response allocates only servers that can successfully operate in the tier. A XenEnterprise image captured from an image host with an IDE disk will not run on a server with a SATA disk and vice versa. If you have both disk types in your environment, mark each type with a custom attribute. Mark this image with the custom attribute that identifies the disk type of the image host.
	XenEnterprise Server memory requirement: Cassatt Active Response defaults this value to 224 Mbytes. Refer to the XenEnterprise documentation to determine whether you need a different value. Note that XenEnterprise needs a small amount of unallocated memory for housekeeping functions.
	VM requirements: Cassatt Active Response defaults memory for each VM to 256 Mbytes. Refer to the blueprints for your applications to determine whether your VMs require a different value. Determine how many VMs your application nodes can run based on the amount of memory each one needs, the amount of memory required for XenEnterprise Server, and the amount of memory available in your application nodes.
	Capacity requirements: Determine the capacity requirements for the XenEnterprise host tier. For more information, see Understanding Tier Configuration and Personalization.
	Network Requirements: For context and background, read Understanding Cassatt Active Response Network Manager. Be aware that: Xen guest tiers are limited to those networks you select for the XenEnterprise host tier. XenEnterprise does not support VLAN interfaces within VMs; consequently, all networks assigned to the XenEnterprise host tier other than the primary network must use dedicated interfaces. Xen VMs are limited to three NICs, so Xen guest tiers are limited to the primary plus two additional networks. The next diagram provides more information. Primary network: Make sure the network has adequate addresses available for maximum nodes in the host tier plus any VMs the hosts will generate. For more information, see Network Addresses: Calculating Requirements. If necessary, add a new network to Cassatt Active Response using the Controller. Additional networks: Use the Controller to add any additional networks that will be required by guest tiers. Make sure each network has adequate addresses available for maximum nodes in the host tier plus any VMs the hosts will generate. XenEnterprise does not support NIC bonding; Cassatt Active Response nonetheless renames a NIC to "bond0" to keep interface naming consistent across servers.

The blueprint steps

This blueprint differs somewhat from the standard high-level blueprint steps because XenEnterprise does not require a separate operating system.

Step 1: Reserve a node from the free pool to use as an image host

1. From the Controller, click the Free Pool.
2. Select a node to reserve.
3. Select Node Actions > Reserve for Image Capture.
4. Note the node's IP address, which you will use when you install the software and capture the image.
   

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Step 2: Install XenEnterprise

Follow the installation instructions provided in the XenEnterprise user guide, Getting Started With XenEnterprise, to install XenEnterprise Server on the image host. Install licenses as directed by the vendor.

If you will use SNMP for monitoring, set up SNMP as directed in Adding SNMP support to a XenServer Host.

Installing licenses requires that you install the XenEnterprise Administrator Console. The XenEnterprise Administrator Console is not required for the remainder of this blueprint, but is required for blueprints that create and capture XenEnterprise VMs.

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Step 3: Capture the XenEnterprise image

In this step, you will capture the base image from the image host using the cccapture command—an interactive script. Although you can change the values later, it is most efficient to supply valid values now.

Follow these steps:

1. Log into the active control node as root.
2. Enter the following command to start the capture of the base image from the image host:
   
   /opt/cassatt/bin/cccapture
3. Answer each prompt.
   
   The next table lists suggested values for XenEnterprise; unless you have site-specific reasons, you can accept the default values for other cccapture prompts.
   
   For names, descriptions, and other discretionary fields, use values that are meaningful to you. In the image name, do not use spaces or characters (for example, /) special to Unix-based file systems such as Linux.
   
   For file system selection: selecting unneeded file systems wastes space but is otherwise harmless.
   
   

   At this prompt...	Enter...	Notes
   Enter the image type (linux, vmhost, xenhost, xenguest, windows, solaris):	xenhost
   Does this image require local swap space? [n]	y
   Enter the required amount of swap space (in Gbytes): [8]	2	The space remaining on the local disk after swap partitions are created is assigned to local temp space.
   Should this image be installed on the local disk (allowing the node to boot locally)? [y]	y or n	See Alternatives to NFS: Image on Local Disk for details.
   Do you want to specify the hardware requirements for a tier using this image? [n]	y
   Enter the minimum allowed CPU speed in GHz for this image: [no minimum]	1.5
   Enter minimum amount of RAM (MBytes) per node for this image (128, 256, 512, 1024, 2048, 4096, 8192): [no minimum]	1024	Note that the total for the physical node must include sufficient memory for each VM.
   Enter the amount of time in seconds that the system should wait for the services provided by this image to start (after this time has passed, the system will attempt to reboot or replace the node): [600]	900
   OS Monitoring Options Specify the operating system monitoring that will be used for this image (at least one monitoring option must be configured): Monitor via SNMP? [n]	y
   Monitor via ping? [n]	y	If you said "y" to the question, "Should this image be installed on the local disk (allowing the node to boot locally)? [n]", then ping monitoring is not available.
   Ping Timeout (seconds): [15]	30
   XenHost image information: Enter memory reserved for domain0 of the xenhost [224m]:	224	Reserves memory for the XenEnterprise Server.
   Number of Virtual Machines to create [3]:	number of VMs	Cassatt Active Response generates VMs based on these specifications when you activate the XenEnterprise host tier. Make sure the total memory for the VMs and domain0 does not exceed the RAM requirement for the host node.
   Enter information for each Virtual Machine to be created: vm[0]: number of cpu's for virtual machine [1]:	cpus
   vm[0]: memory size for virtual machine (in Mbytes) [256]:	size
   vm[1]: number of cpu's for virtual machine [1]:	cpus
   vm[1]: memory size for virtual machine (in Mbytes) [256]:	size
   ...

If you will be capturing a Xen VM image, it is most efficient to keep the same image host reserved with the XenEnterprise software intact. When you have completed this blueprint, simply begin the business application blueprint of your choice using the same image host.

Cassatt Active Response always configures local temp space for xenhost-type images. Do not deselect the local disk or the /tmp checkbox for this image in the Controller.

Cassatt automatically configures a script monitor for VM host images. Do not disable or modify the script monitor for this image from within the Controller.

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Step 4: Create the tier

Return to the Controller to define the XenEnterprise host tier. Cassatt Active Response prepopulates tier values with the parameters you set during image capture. If necessary, you can change them during tier creation.

1. On the left navigation pane, click Domain or Tiers to display the Tier List.
   
2. On the Tier List page, click the New Tier button (on the right).
3. On the Properties page, set the properties for the XenEnterprise host tier. The next table lists the suggested values for the XenEnterprise host tier; unless you have site-specific reasons, you can accept the defaults in other fields.
   
   

   At this prompt...	Enter...	Notes
   Email Alerts	On
   Email On: Tier Critical Tier Non-Critical		Select all choices
   Automatic move to maintenance pool	On	Setting both of these to "On" is most effective for virtual application node management with Cassatt Active Response. For more information, see the sidebar Understanding host application node/virtual application node dependencies.
   Reboot on failure	On
   Harvest priority	High
   Allow harvest	Off

4. On the Requirements page, set the hardware requirements for the tier.
   
   

   At this prompt...	Enter...	Notes
   Operational Target	TargetNodes	Set MinNodes = TargetNodes = MaxNodes Remember that GuestNodes = TargetNodes x VMs. Set target nodes according to the number of guest nodes you need and the number of VMs in your image.
   Minimum Nodes	MinNodes
   Maximum Nodes	MaxNodes

5. On the networks page, select a primary network and any additional networks required by your Xen guest tiers. Select the Dedicated checkbox for all networks other than the primary.
6. On the IPs and Hostnames page, assign IP addresses or host names, or accept the default settings.
7. You can close the Creating Tier Progress page and continue with the next section.

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Step 5: Personalize the image instances

The blueprint does not require personalizing the tier.

Step 6: Allocate nodes and activate the tier

Follow these steps to allocate nodes and activate the tier.

1. From the Tiers table on the Domain page, select the checkbox for the XenEnterprise host tier.
2. From the Tier Actions dropdown menu, select Allocate Nodes. Click Allocate Nodes on the confirmation page.
   
   Cassatt Active Response allocates nodes and displays the Tiers table.
3. Again, select the checkbox for the XenEnterprise host tier.
4. From the Tier Actions dropdown menu, select Activate. Click Activate on the confirmation page.
   
   Cassatt Active Response starts the operating system and the applications on each node in the tier.
   
   Cassatt Active Response generates virtual application nodes and lists the nodes in the discovered pool.
   
   Cassatt Active Response automatically assigns the custom attribute Xen32pae to the nodes, and it assigns rack and slot values to the VMs.

Do not remove the Xen32pae custom attribute: Cassatt Active Response uses it to assign Xen virtual application nodes to VM guest tiers, and cannot do so if the attribute is missing.

Do not edit the slot field for VMs: Cassatt Active Response needs the automatically generated value to power virtual application nodes on and off.

5. If Automatic Node Inventory and Automatic Move To Free Pool are set to "On," Cassatt Active Response lists the nodes in the free pool; otherwise, Cassatt Active Response lists the nodes in the discovered pool. Select the nodes from the discovered pool, inventory the nodes, and move them to the free pool to make them available to run applications.

The XenEnterprise Administrator Console is disabled for VMs in the Cassatt Active Response environment. Why? XenEnterprise Administrator Console operations conflict with Cassatt Active Response automation. Using a tool other than Cassatt Active Response to affect VM deployment to physical machines or to start or stop VMs could cause service disruptions as these changes are overridden by Cassatt Active Response. Be aware that this means you will not be able to install licenses on individual VMs generated by this tier: it is up to you to track and comply with your license agreements.

This completes the procedure to create and deploy a XenEnterprise image. Next, use a blueprint to create and capture an image with your business application and deploy it in a VM guest tier.

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