Product Documentation

Scalability considerations

Sep 23, 2016

Installing and running Session Recording requires few additional resources beyond what is necessary to run XenApp. However, if you plan to use Session Recording to record a large number of sessions or if the sessions you plan to record will result in large session files (for example, graphically intense applications), consider the performance of your system when planning your Session Recording deployment.

For more information about building a highly scalable Session Recording system, see http://support.citrix.com/article/CTX200869.

Hardware recommendations

Consider how much data you will be sending to each Session Recording Server and how quickly the servers can process and store this data. The rate at which your system can store incoming data must be higher than the data input rate.

To estimate your data input rate, multiply the number of sessions recorded by the average size of each recorded session and divide by the period of time for which you are recording sessions. For example, you might record 5,000 Microsoft Outlook sessions of 20MB each over an 8-hour work day. In this case, the data input rate is approximately 3.5MBps. (5,000 sessions times 20MB divided by 8 hours, divided by 3,600 seconds per hour.)

You can improve performance by optimizing the performance of a single Session Recording Server or by installing multiple Session Recording Servers on different computers.

Disk and storage hardware

Disk and storage hardware are the most important factors to consider when planning a Session Recording deployment. The write performance of your storage solution is especially important. The faster data can be written to disk, the higher the performance of the system overall.

Storage solutions suitable for use with Session Recording include a set of local disks controlled as RAID arrays by a local disk controller or by an attached Storage Area Network (SAN).

Note: Session Recording should not be used with Network-Attached Storage (NAS), due to performance and security problems associated with writing recording data to a network drive.

For a local drive set up, a disk controller with built-in cache memory enhances performance. A caching disk controller must have a battery backup facility to ensure data integrity in case of a power failure.

Network capacity

A 100Mbps network link is suitable for connecting a Session Recording Server. A gigabit Ethernet connection may improve performance, but does not result in 10 times greater performance than a 100Mbps link.

Ensure that network switches used by Session Recording are not shared with third-party applications that may compete for available network bandwidth. Ideally, network switches are dedicated for use with the Session Recording Server.

Computer processing capacity

Consider the following specification for the computer on which a Session Recording Server is installed:

  • A dual CPU or dual-core CPU is recommended
  • 2GB to 4GB of RAM is recommended

Exceeding these specifications does not significantly improve performance.

Deploy multiple Session Recording servers

If a single Session Recording Server does not meet your performance needs, you can install more Session Recording Servers on different machines. In this type of deployment, each Session Recording Server has its own dedicated storage, network switches, and database. To distribute the load, point the Session Recording Agents in your deployment to different Session Recording Servers.

Database scalability

The Session Recording Database requires Microsoft SQL Server 2014, Microsoft SQL Server 2012, or Microsoft SQL Server 2008 R2. The volume of data sent to the database is very small because the database stores only metadata about the recorded sessions. The files of the recorded sessions themselves are written to a separate disk. Typically, each recorded session requires only about 1KB of space in the database, unless the Session Recording Event API is used to insert searchable events into the session.

The Express Editions of Microsoft SQL Server 2014, Microsoft SQL Server 2012, and Microsoft SQL Server 2008 R2 impose a database size limitation of 10GB. At 1KB per recording session, the database can catalog about four million sessions. Other editions of Microsoft SQL Server have no database size restrictions and are limited only by available disk space. As the number of sessions in the database increases, performance of the database and speed of searches diminishes only negligibly.

If you are not making customizations through the Session Recording Event API, each recorded session generates four database transactions: two when recording starts, one when the user logs onto the session being recorded, and one when recording ends. If you used the Session Recording Event API to customize sessions, each searchable event recorded generates one transaction. Because even the most basic database deployment can handle hundreds of transactions per second, the processing load on the database is unlikely to be stressed. The impact is light enough that the Session Recording Database can run on the same SQL Server as other databases, including the XenApp or XenDesktop data store database.

If your Session Recording deployment requires many millions of recorded sessions to be cataloged in the database, follow Microsoft guidelines for SQL Server scalability.