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Citrix Systems 4.2 manual System Reliability and High Availability, HA for Management Server

Models: 4.2

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Chapter 18.

System Reliability and High Availability

18.1. HA for Management Server

The CloudPlatform Management Server should be deployed in a multi-node configuration such that it is not susceptible to individual server failures. The Management Server itself (as distinct from the MySQL database) is stateless and may be placed behind a load balancer.

Normal operation of Hosts is not impacted by an outage of all Management Serves. All guest VMs will continue to work.

When the Management Server is down, no new VMs can be created, and the end user and admin UI, API, dynamic load distribution, and HA will cease to work.

18.2. HA-Enabled Virtual Machines

The user can specify a virtual machine as HA-enabled. By default, all virtual router VMs and Elastic Load Balancing VMs are automatically configured as HA-enabled. When an HA-enabled VM crashes, CloudPlatform detects the crash and restarts the VM automatically within the same Availability Zone. HA is never performed across different Availability Zones. CloudPlatform has a conservative policy towards restarting VMs and ensures that there will never be two instances of the same VM running at the same time. The Management Server attempts to start the VM on another Host in the same cluster.

HA features work with iSCSI or NFS primary storage. HA with local storage is not supported.

18.3. Dedicated HA Hosts

One or more hosts can be designated for use only by HA-enabled VMs that are restarting due to a host failure. Setting up a pool of such dedicated HA hosts as the recovery destination for all HA- enabled VMs is useful to:

•Make it easier to determine which VMs have been restarted as part of the CloudPlatform high- availability function. If a VM is running on a dedicated HA host, then it must be an HA-enabled VM whose original host failed. (With one exception: It is possible for an administrator to manually migrate any VM to a dedicated HA host.).

•Keep HA-enabled VMs from restarting on hosts which may be reserved for other purposes.

The dedicated HA option is set through a special host tag when the host is created. To allow the administrator to dedicate hosts to only HA-enabled VMs, set the global configuration variable ha.tag to the desired tag (for example, "ha_host"), and restart the Management Server. Enter the value in the Host Tags field when adding the host(s) that you want to dedicate to HA-enabled VMs.

Note

If you set ha.tag, be sure to actually use that tag on at least one host in your cloud. If the tag specified in ha.tag is not set for any host in the cloud, the HA-enabled VMs will fail to restart after a crash.

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Citrix Systems 4.2 manual System Reliability and High Availability, HA for Management Server, HA-Enabled Virtual Machines
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4.2 specifications

Citrix Systems, a leading provider of virtualization solutions and cloud computing technologies, released version 4.2 of its popular software, Citrix XenApp, which was previously known as Presentation Server. This version marked a significant evolution in providing users with remote access to applications and desktops, emphasizing simplicity, performance, and security.

One of the standout features of Citrix XenApp 4.2 is its improved application streaming capabilities. This technology allows applications to be delivered to users in real-time, reducing the need for extensive local installations and enhancing the user experience. With application streaming, administrators can efficiently manage applications on a central server while ensuring that users have immediate access to the necessary tools.

Another highlight of this version is the enhanced security measures put in place to protect sensitive data. Citrix XenApp 4.2 includes support for SSL encryption, providing a secure communication channel for data transmitted between the server and clients. This is particularly crucial for businesses that need to comply with strict data protection regulations. Additionally, the integration of endpoint security features ensures that unauthorized access to applications is minimized.

Performance enhancements are also a critical focus in this release. Citrix optimized the delivery of applications over various network conditions, ensuring that users experience minimal latency regardless of their location. This was achieved through the incorporation of SmartAccess and SmartControl technologies, which allow administrators to set policies based on user roles, device types, and network conditions. This level of granularity enables organization-wide security without compromising on usability.

The user experience was further improved with a revamped interface, making it easier for end-users to access their applications and data. Simplified menus, clear navigation paths, and the ability to customize user settings contributed to a more efficient workflow, allowing users to focus on their tasks rather than struggling with the software.

Finally, Citrix XenApp 4.2 was designed to be highly scalable. Organizations of all sizes could deploy this solution to deliver applications efficiently, adapting to their specific needs as their user base grows or changes. This flexibility is crucial for businesses looking to future-proof their IT investments while maintaining optimal performance.

In summary, Citrix XenApp 4.2 stands out with its enhanced application streaming, robust security features, improved performance under varying conditions, user-friendly interface, and scalability, making it an ideal choice for organizations seeking to leverage virtualization for remote access to applications and desktops.