In today’s IT world, the magical word that drives all businesses is “Zero Downtime”. More than a requisite, it is the key for any organization to deliver exceptional customer experience. With data availability being the key to achieve zero downtime, Double take would be one of the best solutions.
Double Take is a data recovery solution for Microsoft windows server to protect the business critical data from loss without downtime. Disaster Recovery plays a vital role in any IT strategy and one need to have a proper DR plan in place based on the business requirement. Double take enables to replicate data, application to any storage without any disruption. This article would walk you through systematic configuration of Double take.
Double take performs 3 operations.
By mirroring process, the data from the source will be replicated to the target and would enable high availability. The Double-Take solution mirrors all of the selected data that included the file attributes and permissions.
- Identical files are not mirrored.
- New files, different files can be mirrored.
- Checksums can calculate blocks of data to be mirrored.
Double-Take replication process enables to track the changes at the file system level. Replicating is a more efficient method of maintaining a real-time copy and transmit of file to the target server.
1. A user or application updates part of a file.
2. Only the changed portion of the file is replicated to the target.
3. An up-to-date copy of the file is maintained on the target.
Failover is the process in which a target stands in case of the source fails. As a result, user and application requests that are directed to the failed source are routed to the target.
Double-Take monitors the source status and tracks the requests and responses exchanged between the source and target. When a monitored source does not respond to the target’s requests, Double-Take assumes that the server has failed. Double-Take initiates the failover if it is configured automatically, if not, it stimulates the network administrator. The failover target assumes the identity of the failed source, and user and application requests destined for the source server or its IP address(es) are routed to the target.
- Double take Availability Applications should run on a separate server.
- Source server and Destination server should be on the same operating system.
- Minimum Memory and hard disk should be 2 GB and 33 GB respectively.
- Both servers should be in the same domain.
Installing Double-Take Availability Software
- Launch the Double-Take installer and select Double Take Availability to begin the installation process.
- In the next few steps, you will be prompted to install pre-requisites and perform a check for an updated installer from the manufacturer website.
- It is highly recommended that you accept all updates and prerequisites automatically applied by the installer.
- Select Client and Server Components to install the application and the management utilities.
- Install the management utilities on both servers, as they will be needed in the event of a system failure.
- Enter the activation code provided by the manufacture for this deployment and click Add. Once the code is accepted, click Next to continue.
- Specify the amount of RAM to be dedicated to the Double Take application. While the minimum requirement is 512MB, it is recommended that we allocate at least 1024MB of RAM.
Continue through the installation process until the wizard is complete. The Double-Take application server is now installed and ready to be configured.
Configuring Double-Take Data Replication
- Choose Start > Programs > Double-Take and load the Double-Take Console. From the Tasks menu, choose Add Servers.
- Enter the hostname of the primary server in the Server box. Enter a valid user name and password with administrator permissions on the host, and click Add. Repeat this step to add the destination server, and click OK to exit the wizard.
- Click the Manage Servers icon at the top of the console and verify that both hosts have been added.
If it throws an error, delete the hosts and add them again post verifying the credentials entered.
- To configure replication, right click the server icon and select protect in the list.
- Choose the Workload types to replicate.
- The source server is the replication master that will hold the primary dataset that will be mirrored to the destination server
- Then, click next and the next page would let us choose the Destination Server.
- After selecting the destination server, in the next page,we need to configure the SET OPTIONSunder the Failover identity select Retain Target Network Configuration and then enable Update DNS Server.
- In the DNS OPTIONS, give the credentials of the DNS servers which would be updated during failover, by clicking Change
- Select the Target IP Address by clicking the drop down menu.
- Under the Reverse Protection and Routing Select the Target Server Route.
- Then Enable the Reverse Protection and mention the Reserved IP Address for both source and Target Servers.
- Under the Compression tab, enable the Compression and select as medium. Then Click Next to Continue.
Migrating Services to a Failover Server
- After Completing the Step 8, Double Take will review the checklist automatically. Once done, Click finish. (Avoid Warnings and click finish).
- Under the Manage jobs, you will see the files and data synchronising between source and destination. It takes a Few minute to complete the Synchronising.
- After completion of synchronising,the source server is ready to protect. When the source server fails, the destination server will give the Failover option.
- Here, the Source system is ready to failover. Now we can shut down the source system.
- After the source server shutdown, then the double take management service cannot communicate with source server and it will make decision as – met failover.
- Now, click the Manage Jobs icon and select the job to failover.
- If the primary server is offline the job will show in failed state.
- Right-click the job and choose Failover from the menu to start the failover wizard.
- Select the Fail over live data radio button and click Failover to transfer services to the secondary server.
- Once the failover job is submitted, the IP address from the primary server gets configured on the secondary server and it appears on the network as the primary server.
- During the time of failover process, the destination server will be restarted automatically and you will see the source server data and files in the destination server (it changes the source server now).
- When the primary server becomes active (on state), it is kept as a destination server so that when the current Source server fails, it takes the reverse option to take the Destination server by giving the reverse option.
- Turn on the primary server (172.16.36.214)
- While it turns on, it is kept as a Stand by only. When the current server fails then it takes over the Secondary server.
- After giving the reverse migration, the server 172.16.36.214 becomes Secondary and 172.16.36.181 becomes Primary.*IP taken from the example
- When the primary server 172.16.36.181 fails, it would again failover to 172.16.36.214.
- It takes some time to restore the files. After completion of restoring the server (172.16.36.181), it is kept as primary and the 172.16.36.214 as a secondary
With this, the Double take configuration is complete and would enable us to reduce downtime & increase availability of resources. Be it a small or larger enterprise data recovery is very important, so for a BCP (Business Continuity Planning) Double take is a proper solution to consider to protect your application and server. If you have any questions about Double-Take, drop us an Email.
Written by Pasupathi
Pasupathi, an enthusiastic and a go-getter working as a Junior- Technology Specialist in Kryptos handling Exchange, O365, Azure, AWS, Citrix and VMware virtualization. He is Microsoft certified solution expert, Azure Infrastructure Architect and AWS Certified Solution Architect. He is a gadget freak and finds time to pen down his thoughts as poems.