Integrating SharePoint Online and On-Premises
Organizations can integrate SharePoint Online and SharePoint Server on-premises to get some of the benefits of Microsoft hosting while keeping some SharePoint sites in-house. SharePoint Online, an Office 365 service, offers multitenant hosting of SharePoint installations in Microsoft data centers. A hybrid SharePoint system combining Microsoft-hosted and on-premises installations can be valuable during gradual migrations to SharePoint Online and in cases where some parts of the organization cannot migrate. However, a hybrid system will be more complex than a pure on-premises or online SharePoint system, which can diminish the benefits of a SharePoint Online migration.
Why Combine Online and On-Premises?
An organization might end up with both on-premises and Microsoft-hosted SharePoint installations for several reasons.
Gradual migration. The organization is migrating to SharePoint Online but needs to keep existing on-premises sites working during the migration. The existing sites might need redesign for compatibility with SharePoint Online, or the organization might just need time to move large volumes of data from its existing sites.
Long-term coexistence. An organization might decide to keep specific sites on-premises indefinitely, while moving others to SharePoint Online. This might be necessary because the on-premises sites have sensitive data that the organization cannot put in an external multitenant data center, or because the sites have features that are not compatible with SharePoint Online and cannot be redesigned cost-effectively. A company might also maintain separate SharePoint Online and on-premises installations for licensing reasons: for example, it might put business intelligence sites that require premium licenses in a SharePoint Online installation, accessible only to users who need the features, while most of its sites and users remain on-premises.
Integrating Search, OneDrive, and Application Access
Organizations can integrate SharePoint Online and SharePoint Server 2013 on-premises to improve service to users during a gradual migration or long-term coexistence. In particular, they can integrate search, user collaboration sites, and access to on-premises applications across the installations.
Combining Online and On-Premises Search
Organizations can configure SharePoint Online and SharePoint Server on-premises so that users can search across both installations. For example, organizations can enable "outbound hybrid" search: queries issued to SharePoint Server on-premises return search results from both on-premises and SharePoint Online. With more work, an organization can enable "inbound hybrid" search (queries to SharePoint Online also return results from SharePoint Server) and "two-way" search that works in both directions.
Outbound hybrid search can be valuable in several situations. For example, during long-term coexistence an organization might host sensitive sites on-premises and less sensitive sites on SharePoint Online. Outbound search enables on-premises site users to also search the less sensitive sites, while SharePoint Online users can only search the less sensitive sites hosted there. Similarly, the organization might opt for inbound hybrid search in cases where selected sites are online (for example, collaboration sites for its mobile sales force) but the bulk of its sites are on-premises. An organization might opt for two-way hybrid search during a long-term migration so that users can find content wherever it resides at the moment.
In general, hybrid search requires the organization to integrate user identities between its on-premises Active Directory and the Azure Active Directory that supports SharePoint Online; something the organization will probably have to do for a large-scale Office 365 installation in any case. However, SharePoint hybrid search also requires additional infrastructure. (See the illustration "Search of SharePoint Online from On-Premises".)
Hybrid search has limitations. In general, users see results from different SharePoint installations in separate lists: results from SharePoint Online and SharePoint on-premises are not integrated together in one list. Searches could be slower, because a query does not complete until both installations have been searched. Organizations also need SharePoint Server 2013 on-premises, which complicates the use of hybrid search to support migration to SharePoint Online from older SharePoint versions, although an organization could set up a SharePoint Server 2013 installation to index (crawl) an installation on an older version. Partners such as BA Insight offer products that remove some of these limitations.
OneDrive for Business Online, SharePoint On-Premises
With SharePoint Server 2013 SP1, organizations can redirect some or all of their OneDrive for Business personal collaboration sites to SharePoint Online, while keeping other types of sites on-premises. OneDrive for Business sites, previously known as SkyDrive Pro or My Sites, are provisioned for each user and offer file storage, file synchronization across the user's devices, file sharing with other users, and Office document collaboration (such as concurrent editing with colleagues).
Organizations might redirect OneDrive for Business sites for several reasons. The sites are among the easiest to move from SharePoint on-premises to SharePoint Online because they do not have custom code or other features that would block migration, so organizations might redirect them in the early phase of a gradual migration. OneDrive for Business sites are also good candidates for a move to SharePoint Online during long-term coexistence. Users often employ OneDrive sites to work with documents from mobile devices and to share documents with customers or partners, so they are a good fit for SharePoint Online, which is Internet-connected and integrates with Microsoft's mobile device client software (such as Office for iPad). SharePoint Online also enables organizations to quickly increase storage, which can be especially valuable for OneDrive for Business sites, which can grow unpredictably.
OneDrive for Business redirection requires SharePoint Server 2013 SP1 on-premises. The organization redirects the "OneDrive" link to SharePoint Online for all users, or for selected users using SharePoint Server's "audience" feature (which personalizes SharePoint for specific groups). Redirection requires identity integration like that required by hybrid search, and the organization would often want hybrid search so that users can search their OneDrive for Business sites along with other SharePoint sites using a single query. If the organization redirects only a specific audience to SharePoint Online, the organization will also probably need to script a process for provisioning users: for example, every user in the online audience will need SharePoint Online user license assigned, something that the redirection operation does not handle automatically.
Accessing Applications On-Premises
Users can view and edit data from on-premises applications in the SharePoint Online Web interface through a hybrid Business Connectivity Services (BCS) installation. SharePoint Online users can also access on-premises SAP applications through a hybrid installation and Duet Enterprise Online, which enables users to view and edit data, participate in SAP workflows, and request SAP reports.
As with BCS and Duet on-premises, the BCS and Duet hybrid options can speed up business processes by enabling selective "self-service" entry of data (such as expense reports), approvals, and report reviews. The options are likely to be used during long-term coexistence, enabling the organization to serve traveling workers and external partners from SharePoint Online but giving them selective access to on-premises data for specific tasks.
Hybrid BCS and Duet require identity integration and other infrastructure like that for inbound hybrid search. They also require BCS and Duet components to be enabled on both the SharePoint Online and SharePoint Server 2013 on-premises installations. The on-premises SharePoint components must also be integrated with the source applications on-premises, a major task, but one that would also be required for an on-premises installation of the technologies. Finally, the employees accessing the SharePoint Online installation will require premium licenses (typically, Office 365 E3, SharePoint Online Plan 2, or similar).
Compared to on-premises BCS and Duet, the hybrid configurations also have some limitations. For example, SharePoint Online does not enable search of data brought in through BCS.
Integration and Licensing Could Limit Benefits
Organizations considering integrating SharePoint Online and a SharePoint Server installation on-premises should also note the drawbacks of the approach, which could limit the upfront cost savings and other benefits of a move to SharePoint Online.
In general, an organization will need to maintain infrastructure and supporting staff for its on-premises SharePoint installation. It will also require additional infrastructure and staff for integration with SharePoint Online. Apart from the infrastructure discussed above, the organization might require additional infrastructure to maintain consistency between the installations in other areas. For example, each installation has its own site navigation and page templates, content management components (such as the system of metadata properties used to describe stored content), installed applications, and content. Inconsistencies in these areas can confuse end users and complicate management by administrators, particularly for processes such as records management and eDiscovery (capture of content for legal cases) that need to work across both installations. Some Microsoft partners offer SharePoint Server software add-ons that can help maintain consistency with a SharePoint Online installation, but organizations will still need people and hardware to operate the software. The organization will also probably need to hire a consulting firm that has done a hybrid SharePoint project to get the system set up and working reliably end-to-end.
Licensing costs could also be an important factor. In general, employee access to a SharePoint Online installation requires a user subscription license with appropriate rights. This means that opening up outbound hybrid search, for example, could require licenses for many more employees, even if the employees only occasionally access data in the SharePoint Online installation.
SharePoint Online capabilities and limitations are covered in more detail in "SharePoint Online Versus On-Premises" on page 10 of the Aug. 2014 Update.
BA Insight SharePoint search solutions are discussed at http://www.bainsight.com.
Video presentations about SharePoint hybrid include channel9.msdn.com/Events/SharePoint-Conference/2014/SPC339 and channel9.msdn.com/Events/SharePoint-Conference/2014/SPC320.
A search partner presentation on SharePoint hybrid search is at www.slideshare.net/Netwoven/office-365-hybrid-search-strategy-webinar-presentation.
A technical documentation starting point for SharePoint hybrid infrastructure is at technet.microsoft.com/library/jj838715(v=office.15).aspx.
A blog series covering hybrid SharePoint configuration step-by-step begins at blogs.msdn.com/b/spses/archive/2013/10/22/office-365-configure-hybrid-search-with-directory-synchronization.aspx.