Related Topics
Review the table below to determine if your server is a compatible target.
| Requirement | Configuration |
|---|---|
| Operating system version | The source and the 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. |
| Domain | The domain of the source should be the same as the domain of the target. |
| 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. |
| 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 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, unless you configure the advanced options. If there are more NICs on the target than the source, the additional NICs will still be available after failover. |
| File system format | The source and the target must have the same file system format. For example, an NTFS volume cannot be sent to a FAT volume. |
| HAL type and version | The Windows hardware abstraction layer (HAL) refers to a layer of software that deals directly with your computer hardware. The HAL type and version do not have to be identical, but they must be compatible between the source and the target. If the two are incompatible, Double-Take Availability will warn you. In that case, you must upgrade or downgrade the target. |
| Administrative shares | The Full-Server Failover Manager console must be able to access administrative shares on the source and the target. |
| Boot volume configuration | The target boot volume cannot be a dynamic disk configuration. The boot volume is the disk volume that contains the Windows operating system and supporting files. By default, the operating system files are in the \Windows folder, and the supporting files are in the \Windows\System32 folder. The boot volume might be the same volume as the system volume, but that configuration is not required. |
| System volume | The target must have the same system volume as the source. The system volume is the disk volume that contains the hardware-specific files that are needed to start Windows. The system volume might be the same volume as the boot volume, but that configuration is not required. |
| Logical volumes | There are no limits to the number of logical volumes, although you are bound by operating system limits. The source and the target must have the same number of logical volumes, and the source and the target must have the same drive letters. For example, if the source has drives C: and D:, the target cannot have drives D: and E:. In this case, the target must also have drives C: and D:. |
| 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 Availability path | Double-Take Availability must be installed on the system path on the source and the target. |
| Double-Take Availability data state | The source should be from a time when the Double-Take Availability data state is good. If you are using snapshots, you may want to use a snapshot from the last good data state. |
| Capacity and free 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. You must also have enough space on the target to process and apply the system state data. Double-Take Availability performs several validation checks to determine if adequate disk space is available. First, the target must have enough free space on its system volume to hold the entire volume(s) (free and used) from the source. If this first validation check passes, then no additional checks are necessary. Otherwise, there must be at least enough free space on the target system volume to store the system path (including the location of the Windows files, Program Files, and Documents and Settings) from the source. If this second validation check passes, then no additional checks are necessary. If this second validation fails, Double-Take Availability will check to see if a previous failover may have been attempted. Since Double-Take Availability can reuse the disk space from a previous failover attempt, it will add the size of that data to the amount of free space available. If that is enough space for the failover, the failover will continue. If not, you will either have to select a different target or delete files on the target to free disk space. |