Junos Space Virtual Appliance Overview
The Junos Space Virtual Appliance consists of preconfigured Junos Space software with a built-in operating system and application stack that is easy to deploy, manage, and maintain.
A Junos Space Virtual Appliance includes the same software and all the functionality available in a Junos Space physical appliance. However, you must deploy the virtual appliance on the VMware ESX Server, which provides a CPU, hard disk, RAM, and a network controller, but requires installation of an operating system and applications to become fully functional.
Just as you can install additional physical appliances to create a fabric to provide scalability and availability, you can deploy multiple virtual appliances to create a fabric that provides the same scalability and high availability as a fabric of physical appliances.
You can create a fabric of JA1500 Junos Space appliances, Junos Space virtual appliances, or a hybrid fabric of both physical and virtual appliances.
Understanding How Nodes Are Connected in a Fabric
Each Junos Space appliance (physical or virtual) that you install and configure is represented as a single node in the fabric. You can add nodes without disrupting the services that are running on the fabric. When you install and configure the first appliance, Junos Space automatically creates a fabric with one node. For each additional appliance you install and configure, you must add a node to logically represent the appliance in the fabric. You add nodes to the fabric from the Administration workspace in the Junos Space user interface. Each node that you add to the fabric increases the resource pool for the node functions to meet the scalability and availability requirements of your network. By default, Junos Space automatically enables node functionality across the nodes in the fabric to distribute workload. The nodes in the fabric work together to provide a virtualized resource pool for each of the node functions: load balancer, database, and application logic.
In a fabric comprising two or more nodes, Junos Space provides failover when a node functioning as the active server (load balancer server or database server) goes down. By default, Junos Space marks a particular node down and routes failover requests to the node that Junos Space designates as standby server. Junos Space uses a heartbeat mechanism to check whether the nodes in the fabric are running. When a node functioning as the active server fails (the appliance crashes or stops sending heartbeats), the node functioning as the standby server takes over all resources that were managed by the node functioning as active server.
To add, manage, and monitor the nodes in the fabric, a Junos Space user connects to a single Web IP address. The IP address of first (active) node and second (standby) node, and the Web (virtual) IP address must all be in the same subnet. The Web IP needs to work on both the first and second node in the fabric. When both nodes are in same subnet, and the first (active) node goes down, the second (standby) node becomes the active node and packets continue to be directed from the router, to the Junos Space Web IP, and then to the second node, because both nodes are in same subnet. However, if the second (standby) node is configured in a different subnet than the first (active) node, and the first node goes down, the second node becomes the active node, but because the Web IP now points to the different subnet of the second node, all packets originally destined for first node won’t be received by the second node.
Virtual Appliance Deployment
The Junos Space Virtual Appliance is stored in the Open Virtualization Format (OVF) 1.0 and is packaged as an *.ovf file, which is a tar file that contains all the files of the Junos Space Virtual Appliance. OVF is not a bootable format, and you must deploy each Junos Space Virtual Appliance to a hosted ESX server before you can run the Junos Space Virtual Appliance.
For release 1.0 and later, to deploy a Junos Space Virtual Appliance on a VMware ESX server, version 3.5. or higher, you use the VMware vCenter Converter, version 4.0.1 to convert the Junos Space Virtual Appliance to a virtual machine. After the Junos Space Virtual Appliance is converted to a virtual machine, you use the VMware Infrastructure Client that is connected to the VMware ESX Server to deploy the Junos Space Virtual Appliance on the ESX Server.
Recommendations for Deploying Virtual Appliances on the VMware ESX Server
The CPU, RAM, and disk space provided by the VMware ESX server must meet or exceed the documented CPU, RAM, and disk space requirements for deploying a Junos Space Virtual Appliance. In addition, Juniper recommends that, for a multi-node fabric, you deploy the first and second virtual appliance on separate VMware ESX servers to ensure failover support.
The distributed Junos Space Virtual Appliance files are created with 5 GB of disk space, and you add an additional 40GB of disk resources when you first deploy the virtual appliance to a VMware ESX server. In many cases, the 45 GB of disk space will be sufficient; however, if the percent of Junos Space disk resources utilized reaches 80% capacity, Juniper recommends that you add another 40 GB of disk space to your virtual appliance. You can monitor the percent of disk space utilized in the Fabric Monitor inventory panel in the Junos Space user interface.
Configuring an NTP Time Source For Each Appliance
To ensure consistent behavior among all nodes in a multi-node fabric, each node’s time must be synchronized with every other node in the fabric. When you configure each Junos Space Virtual Appliance (and JA1500 Junos Space Appliance) with an NTP server, you ensure that, if the first node (which is used to synchronize time for all nodes in the fabric) goes down, all other nodes in the fabric remain synchronized. To ensure this behavior, all nodes in a fabric must use the same external NTP source that you configure for the first appliance.
 | Note: By default, Junos Space translates time so that the time displayed in the user interface corresponds to Junos Space server time, but the time is mapped to the local time zone of your client computer. |
To ensure time remains synchronized across all nodes in the fabric, Juniper strongly recommends that you use the following guidelines:
- Add an NTP server to the first appliance (physical or virtual) during initial set up.
- For each additional appliance, add the same NTP server
that you specified for the first appliance.
Note: You must add the NTP server before you add the appliance/node to the fabric from the user interface.
