A Power BI Report Server is 100% compatible with SSRS. A Power BI Report Server can be thought of as a superset of an SSRS server in the sense that both modern Power BI reports and all SSRS features through the latest release of SSRS are included. Therefore, it's not necessary to deploy both an SSRS report server and a Power BI Report Server to support existing SSRS workloads.

It's certainly possible to deploy the Power BI Report Server along with an instance of SSRS. For example, the Power BI Report Server could be dedicated to self-service BI reports built with Power BI Desktop, while the SSRS server could be dedicated to IT developed paginated (.RDL) reports.

For the majority of organizations, however, the Power BI Report Server and its modern web portal will be used to consolidate all report types.

There are three main differences between the Power BI Report Server and SQL Server Reporting Services (SSRS):

• Power BI Report (.PBIX) files can only be viewed from the Power BI Report Server's web portal
• Excel workbooks (.XLSX) can only be viewed from the Power BI Report Server's web portal:
  • This requires the OOS, as described in the Configuration section later in this chapter
• The upgrade and support cycles are significantly shorter for the Power BI Report Server:
  • A new version of the Power BI Report Server is released approximately every 4 months
  • Each new version of the Power BI Report Server is supported by Microsoft for 1 year

New versions of SSRS will continue to be tied to the release of SQL Server. For example, SSRS 2017 was made generally available (GA) on October 2nd, 2017, along with SQL Server 2017. Although the upgrade cycle has shortened for SQL Server, it doesn't match the pace of innovation from Power BI's monthly release cycles. Therefore, to make new Power BI features available to customers with on-premises deployments, a new Power BI Report Server is released approximately every 4 months.

Unlike versions of SSRS, which continue to receive support such as cumulative updates for years following their release, support for each Power BI Report Server release ends after one year. Therefore, while upgrading to each new version of the Power BI Report Server every 4 months is not required, organizations should plan to upgrade within one year of each version's release to maintain support. Additional information and considerations on upgrade cycles are included in the Upgrade cycles section later in this chapter.

There are no plans to deprecate SQL Server Reporting Services or replace it with the Power BI Report Server. However, given the additional features exclusive to the Power BI Report Server and the more frequent release cycle, there are strong reasons to choose Power BI Report Server over SSRS going forward. Additionally, an existing SSRS server can be easily migrated to Power BI Report Server as discussed in the Migrating from SQL Server Reporting Services section later in this chapter. 

BI teams familiar with SSRS can quickly take advantage of mature features, such as report subscription schedules and role-based user permissions. For organizations running older versions of SSRS, the significant features introduced in SSRS 2016, including the modern web portal and KPIs, can further supplement their BI solution. In summary, the Power BI Report Server allows organizations to continue to fully support existing and new SSRS reports, while also enabling the self-service and data visualization features of Power BI reports.