written by: Murray White - Solution Architect with Vision SolutionsThe following video demonstrates a migration from existing clustered storage to new clustered storage within the same Windows Server 2003 MS Cluster (32bit), using the Double-Take Move 6.0 product. Key Features * Real-time byte-level replication* Zero downtime during replication/synch. Only downtime is brief, during cutover to new clustered volume.
As this involves clusters, the OS involved must be at least Windows 2003 Enterprise or DataCenter edition.
Enterprise edition OS = DT Availability Advanced editionDatacenter edition OS = DT Availability Premium edition
File system—Double-Take supports the NTFS file system. FAT and FAT32 are no longer supported.
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 needed for the Double-Take program files. For Windows 2003, this is approximately 300 MB. For Windows 2008, this is approximately 375 MB.
The program files can be installed to any volume while the Microsoft Windows Installer files are automatically installed to the operating system boot volume.
Make sure you have additional disk space for Double-Take queuing, logging, and so on
Server name—Double-Take includes Unicode file system support, but your server name must still 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.
Protocols and networking—Your servers must meet the following protocol and networking requirements.
Your servers must have TCP/IP with static IP addressing. (Some job types allow you to add DHCP addresses for failover monitoring, although only after a job has already been created. Keep in mind that depending on your failover configuration, a source reboot may or may not cause a failover but having a new address assigned by DHCP may also cause a failover.)
By default, Double-Take 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 Server and job settings section of DT User Guide for details.
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.
Windows firewall—If you have Windows firewall enabled on your servers, there are two requirements for the Windows firewall configuration.
The Double-Take installation program will automatically attempt to configure ports 6320, 6325, and 6326 for Double-Take. If you cancel this step, you will have to configure the ports manually.
If you are using the Double-Take Console to push installations out to your servers you will have to open firewall ports for WMI (Windows Management Instrumentation), which uses RPC (Remote Procedure Call). By default, RPC will use ports at random above 1024, and these ports must be open on your firewall. RPC ports can be configured to a specific range by specific registry changes and a reboot. See the MS Knowledge Base article 154596 for instructions. Additionally, you will need to open firewall ports for SMB (server message block) communications which uses ports 135-139 and port 445. As an alternative, you can disable the Windows firewall temporarily until the push installations are complete.
See Firewalls section of DT User Guide for instructions on handling firewalls in your environment.
NAT support—Double-Take does not support NAT configurations because you must select an actual IP address on your source and target servers for monitoring and routing data. You cannot use external addresses.
Windows Management Instrumentation (WMI)—Double-Take is dependent on the WMI service. If you do not use this service in your environment, contact technical support.
Clusters—If your job type supports clustering, make sure your cluster meets the following general requirements in addition to any job specific cluster requirements.
Best practices—You should carefully review Microsoft documentation and resources for properly configuring your cluster before implementing Double-Take on a cluster. The Microsoft TechNet articles for Failover Clusters and Installing and Upgrading Cluster Nodes are two resources you can start with. There are many other resources available on the Microsoft TechNet web site.
Networking—The following networking requirements apply to your cluster.
-- You must have TCP/IP connections between nodes.-- Multiple networks are recommended to isolate public and private traffic.-- The private network should be a unique subnet so that Double-Take will not attempt to use an unreachable private network.-- Your network can contain direct LAN connections or VLAN technology.-- For Windows 2003, the cluster nodes must be on the same logical IP subnet.-- For Windows 2003, the maximum round trip latency between nodes should be no more than ½ second.
Domain—The cluster nodes must be members of the same domain.
DNS—Forward and reverse lookups must be implemented on the primary DNS server for the cluster name and individual nodes.
Cluster service account—For Windows 2003 clusters, use the same cluster service account on source and target clusters.
Double-Take disk queue—Ensure that the disk queue is not on a Physical Disk resource.
Volumes—The source and target should have identical drive mappings.
Licensing—Each node in the cluster must have a valid Double-Take Availability activation code.
Resource registration—In some cases, the Double-Take cluster resources may not be registered automatically when Double-Take is installed. You can manually register the resources by running DTResUtility.exe, which is installed in the \Windows\Cluster directory.