Multi-site data replication support for Exchange Server

You can use replication technology to help provide high availability for data in Microsoft Exchange Server 2010, in Microsoft Exchange Server 2007, in Microsoft Exchange Server 2003, or in Microsoft Exchange 2000 Server. Exchange Server replication solutions are provided by third-party software vendors and storage hardware vendors. This article describes our support policies for Exchange when Exchange is used together with a third-party replication mechanism.

For more information about the best practices to use when you implement Exchange data replication, visit the following Microsoft Web site: Note The data replication information that is covered in this article, and that is referenced in the previous white paper refers to live data only. This means that this article only refers to data that is currently accessed by the Exchange program.

Kinds of replication mechanism

Each kind of replication mechanism can be classified according to the following:

• The replication mechanism uses synchronous replication or asynchronous replication.
• The replication mechanism uses host-based replication or storage-based replication.

The kinds of replication mechanism are briefly defined in the following sections to help you understand our support limits for these different kinds of replication mechanism.

Synchronous replication

In a synchronous replication mechanism, a host only receives a write-completed response from the storage system when the I/O write operation is completed in both the local storage location and in the remote storage location.

Asynchronous replication

In an asynchronous replication mechanism, a host receives a write-completed response from the storage system when the write operation is committed to the local storage device. In this scenario, the storage system does not wait for an acknowledgement from the remote storage device.

Host-based replication

Host-based replication typically uses a filter driver to manage replication. A filter driver is host-based software that interrupts the I/O stream to manage the replication operation.

Storage-based replication

Storage-based replication does not operate on the host computer. This kind of replication occurs at the storage device level. This kind of replication is also known as storage-level replication.

Support policies for the different kinds of replication mechanism

Asynchronous replication

Any data that has been replicated asynchronously is supported only by the storage vendor. When you replicate Exchange data by using asynchronous replication, the vendor who provides your replication mechanism must support the Exchange data at the replication destination. We make no claims as to the reliability of or the performance of Exchange solutions that use asynchronous replication. We use the following criteria to support Exchange-related issues that you may experience in an environment where you use asynchronous replication:

• We will only troubleshoot Exchange-specific issues up to the point where the source of the problem can be reasonably attributed to an issue or an incompatibility with the replication mechanism.
• We do not require that you remove the asynchronous replication feature as a precondition of support. However, we may require that you remove the asynchronous replication feature before offering additional support if there is a reasonable basis for doing this and if less disruptive troubleshooting has not been effective.
• If neither Microsoft nor the replication mechanism vendor can resolve a storage-related problem or a replication-related problem, you might have to remove the asynchronous replication mechanism and then revert to an environment that we fully support to continue troubleshooting.

Synchronous storage-based replication

The following two categories of synchronous storage-based replication mechanism exist:

• Deployments that use geographically dispersed clustering solutions
• Deployments that do not use geographically dispersed clustering solutions
  
  Note This includes clustering solutions that are not geographically dispersed and stand-alone servers.

We have a different support policy for each category.

Deployments that use geographically dispersed clustering solutions

In this synchronous storage-based replication category, the nodes that belong to a particular cluster are located in different sites. Exchange servers are generally hosted by the nodes at the primary site. The replication mechanism provides synchronous replication of the Exchange data to the remote site or sites. In a scenario where a problem occurs at the primary site, the Exchange virtual servers fail over to the passive cluster nodes at the remote site. The Exchange virtual server comes online at that remote site and uses the Exchange data that was replicated.

To support Exchange when Exchange is used together with this kind of replication mechanism, the storage system must be listed on the Microsoft Windows Server Catalog Web site under Geographically Dispersed Cluster Solution. For more information, follow these steps:

1. Visit the following Microsoft Web site:
   http://www.windowsservercatalog.com/
2. Click Cluster Solutions.
3. In the left panel, click Geographically Dispersed Cluster Solution under Product category.

The Microsoft Windows Hardware Quality Labs (WHQL) Web site listing includes the following kinds of hardware:

• Server computers
• Fibre Channel (FC) switches
• Host Bus Adaptors (HBA)
• Storage devices

The WHQL Web site does not necessarily specify the method or the particular technology that is used to perform the data replication operation. Therefore, you should contact your replication mechanism vendor to verify that you are using the same replication technology that was tested in the geographically dispersed clustering solution tests.

We fully support Exchange and Exchange-related data in deployments that use a geographically dispersed clustering solution. These deployments are WHQL qualified and use synchronous replication for the Exchange data.

However, your replication mechanism vendor must provide support for the storage solution, the replication component, and the third-party software that your geographically dispersed cluster solution uses.

Please note that there are WHQL qualified geographically dispersed clustering solution that use MNS configuration and that use asynchronous replication for Exchange data. Our support policy for such solutions falls under the same category as the asynchronous replication solutions.

Deployments that do not use geographically dispersed clustering solutions

This section covers all other kinds of synchronous storage-based replication where a geographically dispersed clustering solution is not used. These replication mechanisms rely on other methods to access the replicated Exchange data at the remote site if a failure occurs at the primary site. For example, these mechanisms might use a standby server together with replication and the Exchange Disaster Recovery process.

We fully support Exchange and Exchange-related data in synchronous replication deployments where a geographically dispersed clustering solution is not used. However, your storage vendor must provide support for the storage solution. Additionally, your replication mechanism vendor must provide support for your replication mechanism.

For Windows Server 2003, we recommend that your replication mechanism use the same storage hardware that is listed on the Windows Server Catalog Web site under�Geographically Dispersed Cluster Solution. For more information, follow these steps:

1. Visit the following Microsoft Web site:
   http://www.windowsservercatalog.com/
2. Click Cluster Solutions.
3. In the left panel, click Geographically Dispersed Cluster Solution under Product category.

We also recommend that you use the same replication mechanism that is used in the geographically dispersed cluster solution.

Host-based synchronous replication

If your host-based synchronous replication mechanism is listed as a geographically dispersed clustering solution that is WHCL qualified, we support that solution under the same support policy that we use for a geographically dispersed clustering solution.

If your host-based synchronous replication mechanism is not listed as a geographically dispersed clustering solution that is WHQL qualified, we consider the solution to be in the same category as third-party software. We use the following criteria to support Exchange-related issues that you might experience in an environment where you use third-party software for host-based synchronous replication:

• We will only troubleshoot Exchange-specific issues up to the point where the source of the problem can be reasonably attributed to an issue or an incompatibility with the third-party replication mechanism.
• We do not require that you remove the host-based replication software as a precondition of support. However, we may require that you remove the host-based replication software before offering additional support if there is a reasonable basis for doing this and if less disruptive troubleshooting has not been effective.
• If neither Microsoft nor the replication mechanism vendor can resolve a particular storage-related or replication-related problem, you might have to remove the host-based replication mechanism and revert to an environment that we support to continue the troubleshooting process.

To contact Microsoft Customer Support Services (CSS), visit the following Microsoft Web site:For information about your hardware manufacturer, visit the following Web site: Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.