Primary Storage Outage and Data Loss | Citrix Systems 4.2 guide

Chapter 18. System Reliability and High Availability

18.4. Primary Storage Outage and Data Loss

When a primary storage outage occurs, all hosts in that cluster are rebooted. This ensures that affected VMs running on the hypervisor are appropriately marked as stopped. Guests that are marked for HA will be restarted as soon as practical when the primary storage comes back on line. With NFS, the hypervisor may allow the virtual machines to continue running depending on the nature of the issue. For example, an NFS hang will cause the guest VMs to be suspended until storage connectivity is restored. Primary storage is not designed to be backed up. Individual volumes in primary storage can be backed up using snapshots.

Note

If there are multiple primary storage servers in a cluster and only one goes down, VMs using a healthy primary storage will also be affected, because all hosts are rebooted.

18.5. Secondary Storage Outage and Data Loss

For a Zone that has only one secondary storage server, a secondary storage outage will have feature level impact to the system but will not impact running guest VMs. It may become impossible to create a VM with the selected template for a user. A user may also not be able to save snapshots or examine/restore saved snapshots. These features will automatically be available when the secondary storage comes back online.

Secondary storage data loss will impact recently added user data including templates, snapshots, and ISO images. Secondary storage should be backed up periodically.Multiple secondary storage servers can be provisioned within each zone to increase the scalability of the system.

18.6. Limiting the Rate of API Requests

You can limit the rate at which API requests can be placed for each account. This is useful to avoid malicious attacks on the Management Server, prevent performance degradation, and provide fairness to all accounts.

If the number of API calls exceeds the threshold, an error message is returned for any additional API calls. The caller will have to retry these API calls at another time.

18.6.1. Configuring the API Request Rate

To control the API request rate, use the following global configuration settings:

•api.throttling.enabled - Enable/Disable API throttling. By default, this setting is false, so API throttling is not enabled.

•api.throttling.interval (in seconds) - Time interval during which the number of API requests is to be counted. When the interval has passed, the API count is reset to 0.

•api.throttling.max - Maximum number of APIs that can be placed within the api.throttling.interval period.

•api.throttling.cachesize - Cache size for storing API counters. Use a value higher than the total number of accounts managed by the cloud. One cache entry is needed for each account, to store the running API total for that account.

234

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.

Citrix Systems 4.2 Primary Storage Outage and Data Loss, Secondary Storage Outage and Data Loss

Models: 4.2