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Full server requirements

In addition to the Core Double-Take requirements, use these requirements for full server protection.

• Operating system—The source and target servers can be any operating system listed in the Core Double-Take requirements. However, keep in mind that a target server may meet these requirements but may not be suitable to stand-in for a source in the event of a source failure. See Target compatibility for additional information regarding an appropriate target server for your particular source.
• Operating system language—Your servers must be running the same Windows localized version. For example, if your source is running an English language version of Windows, your target must also be running an English language version of Windows. If your source is running a Japanese language version of Windows, your target must also be running a Japanese language version of Windows. This applies to all localized languages.
• Source and target preparation—Uninstall any applications or operating system features that are not needed from both your source and target. For example, unused language packs will slow down failover since there are thousands of extra files that need to be examined.
• Storage Server Edition—If you are using Windows Storage Server Edition, you will need to check with your NAS vendor to verify if there are technical or license restrictions on failing over an image of a server to different hardware.
• Microsoft Server Core 2008 R2—This operating system is only supported in a Server Core to Server Core configuration.
• Hyper-V servers—Full server protection of a Hyper-V server is not supported.
• Network adapters—NIC teaming is not supported for full server protection.
• Double-Take licensing—If you are protecting a full server in a physical source to virtual target configuration, you will be unable to reverse if your virtual target has a Double-Take Availability Virtual Guest Edition license. If you want to reverse, you will need to have one of the other (non-virtual) Double-Take Availability licenses.

• Microsoft .NET Framework—Microsoft .NET Framework version 3.5 Service Pack 1 is required on the source and target. This version is not included in the .NET version 4.0 release. Therefore, even if you have .NET version 4.0 installed, you will also need version 3.5.1. You can install this version from the Double-Take CD, via a web connection during the Double-Take installation, or from a copy you have obtained manually from the Microsoft web site.

  If you are installing on Server Core 2008 R2, .NET 3.5.1 functionality is included with the operating system but is disabled by default. You will need to enable it prior to installing Double-Take. See your Server Core documentation for the specific commands to enable the .NET functionality.

   

• Supported configurations—The following table identifies the supported configurations for a full server job.

  Configuration		Supported	Not Supported
  Source to target configuration	One to one, active/standby	X
  	One to one, active/active		X
  	Many to one		X
  	One to many 1	X
  	Chained		X
  	Single server		X
  Server configuration	Standalone to standalone	X
  	Standalone to cluster		X
  	Cluster to standalone 2		X
  	Cluster to cluster		X
  	Cluster Shared Volumes (CSV) guest level	X
  	Cluster Shared Volumes (CSV) host level		X
  Upgrade configuration3	Upgrade 5.2 Full Server Failover Manager connection to 6.0 Double-Take Console full server job		X
  	Upgrade 5.3 Double-Take Console full server failover job to 6.0 Double-Take Console full server job	X

  1. If you are using a one to many configuration, you will only be able to configure reverse protection for the first job. Subsequent jobs from that source will have reverse protection disabled.
  2. Full server protection of a cluster is not a default supported configuration, but it is possible with assistance from Professional Services. If you want to use a full server job in a cluster environment, contact Sales or Professional Services. Because this is an advanced configuration, you will be referred to Professional Services for further assistance.
  3. When using a supported upgrade configuration, you can perform a rolling upgrade where you update the target server first. After the upgrade is complete, the source will automatically reconnect to the target. Upgrade the source when convenient. However, after failover you will not be able to reverse until the original source has been upgraded. For an upgrade configuration that is not supported, you will have to delete the existing connection before the upgrade and create a new job after the upgrade.

Target compatibility

• Operating system version—The source and target must have the same operating system. For example, you cannot have Windows 2003 on the source and Windows 2008 on the target. The two servers do not have to have the same level of service pack or hotfix. Windows 2003 and 2003 R2 are considered the same operating system, however the Windows 2008 and 2008 R2 releases are considered different operating systems. Therefore, you can have Windows 2003 on the source and Windows 2003 R2 on the target, but you cannot have Windows 2008 on the source and Windows 2008 R2 on the target. The Windows edition (Standard, Enterprise, and so on) does not have to be the same.

• Server role—The target cannot be a domain controller. Ideally, the target should not host any functionality (file server, application server, and so on) because the functionality will be removed when failover occurs.

  If your source is a domain controller, it will start in a non-authoritative restore mode after failover. This means that if the source was communicating with other domain controllers before failover, it will require one of those domain controllers to be reachable after failover so it can request updates. If this communication is not available, the domain controller will not function after failover. If the source is the only domain controller, this is not an issue.

  Additionally, if your source is a domain controller, you will not be able to reverse protection.

• Architecture—The source and the target must have the same architecture. For example, you cannot failover a 32-bit server to a 64-bit server.
• Processors—There are no limits on the number or speed of the processors, but the source and the target should have at least the same number of processors. If the target has fewer processors or slower speeds than the source, there will be performance impacts for the users after failover.
• Memory—The target memory should be within 25% (plus or minus) of the source. If the target has much less memory than the source, there will be performance impacts for the users after failover.
• Network adapters—You must map at least one NIC from the source to one NIC on the target. If you have NICs on the source that are not being used, it is best to disable them. If the source has more NICs than the target, some of the source NICs will not be mapped to the target. Therefore, the IP addresses associated with those NICs will not be available after failover. If there are more NICs on the target than the source, the additional NICs will still be available after failoverand will retain their pre-failovernetwork settings.
• File system format—The source and the target must have the same NTFS file system format on each server. FAT and FAT32 are no longer supported.
• Logical volumes—There are no limits to the number of logical volumes, although you are bound by operating system limits. For each volume you are protecting on the source, the target must have a matching volume. For example, if you are protecting drives C: and D: on the source, the target cannot have drives D: and E:. In this case, the target must also have drives C: and D:. Additional target volumes are preserved and available after failover, with all data still accessible.
• System path—The source and the target must have the same system path. The system path includes the location of the Windows files, Program Files, and Documents and Settings.
• Double-Take path—Double-Take must be installed on the same path (volume and full directory path) on the source and the target.

• Disk space—The target must have enough space to store the data from the source. This amount of disk space will depend on the applications and data files you are protecting. The more data you are protecting, the more disk space you will need.

  The target must also have enough space to store, process, and apply the source's system state data. If you will be enabling reverse protection, the source must have enough space to store, process, and apply the target's system state data. In either case, the size of the system state will depend on the operating system and architecture. Windows 2003 operating systems need at a minimum 2-3 GB of free space for the system state. Windows 2008 operating systems need at a minimum 7-9 GB of free space for the system state. Windows 2008 R2 operating systems need 10 GB of free space for the system state. These minimums are for a clean operating system installation. Operating system customizations, installed applications, and user data will increase the disk space requirement.

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