Chapter 14. Working With Storage

When a snapshot is taken manually, a snapshot is always created regardless of whether a volume has been active or not.

14.5.4. Snapshot Restore

There are two paths to restoring snapshots. Users can create a volume from the snapshot. The volume can then be mounted to a VM and files recovered as needed. Alternatively, a template may be created from the snapshot of a root disk. The user can then boot a VM from this template to effect recovery of the root disk.

14.5.5. Snapshot Job Throttling

When a snapshot of a virtual machine is requested, the snapshot job runs on the same host where the VM is running or, in the case of a stopped VM, the host where it ran last. If many snapshots are requested for VMs on a single host, this can lead to problems with too many snapshot jobs overwhelming the resources of the host.

To address this situation, the cloud's root administrator can throttle how many snapshot jobs are executed simultaneously on the hosts in the cloud by using the new global configuration setting concurrent.snapshots.threshold.perhost. By using this setting, the administrator can better ensure that snapshot jobs do not time out and hypervisor hosts do not experience performance issues due to hosts being overloaded with too many snapshot requests.

Set concurrent.snapshots.threshold.perhost to a value that represents a best guess about how many snapshot jobs the hypervisor hosts can execute at one time, given the current resources of the hosts and the number of VMs running on the hosts. If a given host has more snapshot requests, the additional requests are placed in a waiting queue. No new snapshot jobs will start until the number of currently executing snapshot jobs falls below the configured limit.

The admin can also set job.expire.minutes to place a maximum on how long a snapshot request will wait in the queue. If this limit is reached, the snapshot request fails and returns an error message.

14.5.6. VMware Volume Snapshot Performance

When you take a snapshot of a data or root volume on VMware, CloudPlatform uses an efficient storage technique to improve performance.

A snapshot is not immediately exported from vCenter to a mounted NFS share and packaged into an OVA file format. This operation would consume time and resources. Instead, the original file formats (e.g., VMDK) provided by vCenter are retained. An OVA file will only be created as needed, on demand. To generate the OVA, CloudPlatform uses information in a properties file (*.ova.meta) which it stored along with the original snapshot data.

Note

For upgrading customers: This process applies only to newly created snapshots after upgrade to CloudPlatform 4.2. Snapshots that have already been taken and stored in OVA format will continue to exist in that format, and will continue to work as expected.

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Citrix Systems 4.2 manual Snapshot Restore, Snapshot Job Throttling, VMware Volume Snapshot Performance
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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.
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