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Source server requirements

This is the server that contains the data you will be protecting.

Operating system—The source server can be a physical or virtual server running any of the following operating system editions.

Windows Server 2008 or 2008 R2 Datacenter, Enterprise (x86, x64), Standard (x86, x64), Web Server, Foundation Server, Small Business Server, or Storage Server Edition.
Windows Server 2003 or 2003 R2 Datacenter, Enterprise (x86, x64), Standard (x86, x64), Web Server, Small Business Server, or Storage Server Edition. Each of the Windows 2003 operating systems require Service Pack 1 or later.

Hyper-V cluster support—Host-level protection is available for Windows Server 2008 R2 clusters.
Architecture—32-bit and 64-bit architectures are supported.
File system—Double-Take RecoverNow supports the same file system formats that Microsoft supports: FAT, FAT32, and NTFS.
System memory—The minimum system memory on each server should be 1 GB. The recommended amount for each server is 2 GB.
Disk space for program files—This is the amount of disk space, approximately 130 MB, needed on the source to hold the Double-Take RecoverNow program files.
Server name—Double-Take RecoverNow includes Unicode file system support, but your server name must be in ASCII format. If you have the need to use a server's fully-qualified domain name, your server cannot start with a numeric character because that will be interpreted as an IP address.
Network protocols—Your servers must meet the following protocol and networking requirements.

Your servers must have TCP/IP with static IP addressing.
By default, Double-Take RecoverNow is configured for IPv6 and IPv4 environments, but the Double-Take service will automatically check the server at service startup and modify the appropriate setting if the server is only configured for IPv4. If you later add IPv6, you will need to manually modify the DefaultProtocol server setting. See the Double-Take Availability Scripting Guide for details on modifying that server setting.
IPv6 is only supported for Windows 2008 servers.
If you are using IPv6 on your servers, your clients must be run from an IPv6 capable machine.
In order to properly resolve IPv6 addresses to a hostname, a reverse lookup entry should be made in DNS.

Microsoft .NET Framework—Microsoft .NET Framework version 3.5 Service Pack 1 is required on the source. 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 RecoverNow CD, via a web connection during the Double-Take RecoverNow installation, or from a copy you have obtained manually from the Microsoft web site.
Snapshots—Double-Take RecoverNow uses the Microsoft Volume Shadow Copy service for snapshot capabilities. To use this functionality, your source must meet the following requirements.

Snapshot operating system—Your source must be running, at a minimum, Windows 2003 Service Pack 1. You should upgrade to Service Pack 2 or later so that several Microsoft patches that address memory leaks in the Volume Shadow Copy service are applied. If you do not have Service Pack 2 installed, you will need to review the patches available on the Microsoft web site and install those that correct the Volume Shadow Copy service memory leaks.
Snapshot file system—Your source must be using the NTFS file system. If you are using a FAT file system, the FAT volumes will not be included in the snapshot set, and when the snapshots are used, the FAT volume will not be time-consistent with the NTFS volumes.
Snapshot data—Snapshots are taken at the volume level. For example, if your job is protecting D:\data and E:\files, the snapshot will contain all of the data on both the D: and E: volumes. If your job is only protecting D:\data (E:\files exists but is not included in the job), the snapshot will only contain the D: volume.
Snapshot configuration—If you have related data on different drives on your source (for example, an Exchange database on one drive and related log files on another), snapshots of each drive must be taken simultaneously so that the snapshots for each drive represent the same point in time. However, based on snapshot technology, different snapshots cannot be taken at the same time. To work around this limitation and guarantee data integrity on the repository server, you need to create a mount point, thus ensuring that one point-in-time consistent snapshot will be taken of both volumes at once. To create a mount point, create an empty folder on one of the drives. Using the Disk Management tool in the Windows Computer Management applet, remove the drive letter from the other drive. Then create a mount point by selecting Mount in the following empty NTFS folder and specifying the folder you just created. If you have multiple drives, create an empty folder on the drive for each of the other drives and create mount points to each of the folders. When the snapshot is taken of the drive, each mount point will be included in the snapshot. You will need to modify your applications to specify the new location for the files that are now on the mount point. For additional details on creating and using mount points, see your Windows reference manual. For details on modifying your applications, see your application reference manual.
Snapshot limitations—Sometimes taking a snapshot may not be possible. For example, there may not be enough disk space to create and store the snapshot, or maybe the target is too low on memory. If a snapshot fails, an Event message and a Double-Take RecoverNow log message are both created and logged. There are also limitations imposed by Microsoft Volume Shadow Copy that impact Double-Take RecoverNow snapshots. For example, for some operating system versions Double-Take RecoverNow maintains only 64 snapshots because Volume Shadow Copy only maintains 64 snapshots. If 64 snapshots exist and another one is taken, the oldest snapshot is deleted to make room for the new one. Other operating system versions may maintain up to 512 snapshots. Another example is that Double-Take RecoverNow snapshots must be created within one minute because Volume Shadow Copy snapshots must be created within one minute. If it takes longer than one minute to create the snapshot, the snapshot will be considered a failure. Additionally, Volume Shadow Copy will not revert snapshots of a volume with operating system files, therefore Double-Take RecoverNow is also unable to revert a volume with operating system files. You must also keep in mind that if you are using extended functionality provided by Volume Shadow Copy, you need to be aware of the impacts that functionality may have on Double-Take RecoverNow. For example, if you change the location where the shadow copies are stored and an error occurs, it may appear to be a Double-Take RecoverNow error when it is in fact a Volume Shadow Copy error. Be sure and review any events created by the VolSnap driver and check your Volume Shadow Copy documentation for details.
Application-consistent snapshots—If you are protecting a server that has SQL Server installed and you want to take application-consistent snapshots, you must be using SQL Server 2005 or 2008. The application consistency feature does not support SQL Server 2000. Additionally, the application consistency feature requires Double-Take RecoverNow version 5.3.