Use of cloud for DR solutions is becoming more common, even the organizations which are not using cloud for mission critical production applications are moving towards using cloud for application DR.

Business Case for Using Cloud for the DR

1. Faster Recovery Time Objective (RTO): Typically DR requires lengthy manual processes to fully restore the business applications at the DR site.  Having backup data and servers at the DR site is easy, however, restoring the entire application or service takes time.  E.g. full application restoration requires starting services in specified order, performing dns and other configuration updates etc.  In Cloud, the IaaS APIs provide ability to use automation solutions like Kaavo IMOD to fully restore the business applications automatically without manual intervention.  As a result organizations get predictable recovery and reduced RTO.  Automating the service or application recovery can reduce RTO to minutes from hours or days.

2. Shorter Recovery Point Objective (RPO): Instead of relying on offsite tape backups, organizations can reduce their RPO to minutes by maintaining near real-time data backups in the Cloud.  For faster transfer of large data dedicated lines can be established between the customer datacenters and the cloud.  The cost of the dedicated line depends on the distance of the customer datacenter from the cloud providers' peering point.  For most use cases VPN lines over internet are sufficient for transferring data between customer datacenter and the cloud.

3. Lower Costs: Typically organizations pay high price for standby infrastructure, especially servers at the DR site.  Using cloud there is no need to pay for the servers when they are not in use at the DR site.  Pay as you use infrastructure model significantly reduces DR costs without compromising the service levels.

Following are some of the best practices and lessons learned from the Cloud DR solutions we have implemented so far:

Cloud DR is Different than Traditional DR
Unlike traditional DR solutions which relies on having a backup infrastructure for the entire datacenter requiring large and costly implementation, Cloud DR can be implemented incrementally application by application.  For example it is common for organizations to have a large shared database with multiple schemas supporting various applications.  In majority of cases this sharing is driven by server consolidation to increase the utilization of internal infrastructure.  Not all applications using a shared database have same service level requirements.  Some applications are more critical than others, so as long as schemas and application data is different, it is better to remove the dependency on shared database by having the right size database for each application in the cloud.  This allows optimal prioritization and incremental delivery of the DR project based on the service levels of the individual applications.

Migration of Applications Using Single Sign-on with LDAP
When planning DR for individual applications it is important to identify the dependent services and making sure that the dependent services would be available as a part of the DR solution.  Enterprise customers typically use Single Sign-on with LDAP for managing authentication.  So best practice is to treat the Single Sign-on Service as the critical application and implement the DR solution for bringing up the Single Sign-on Service first during the DR process.  An automation solution like Kaavo IMOD enables customers to restore applications and services in the specified order automatically during DR without any manual intervention. During a real DR scenario there are many things going and it is easy to make mistakes under pressure if the application restoration process is not fully automated.  To prevent surprises during actual DR, it is important to have a fully automated solution for restoring applications and services.

Restoring Back to Normal Operations after DR
This is one area which is often overlooked or under planned in DR projects.  For companies using their own datacenters for production applications and using cloud for DR, processes and automation must be implemented to fully restore the applications in the customer production datacenter using the latest data from the cloud DR once the primary datacenter is back online.  This step is not required for applications which are using cloud as their primary site.  E.g. if an application is running in one cloud zone and after DR it is running in a different cloud zone there is no need to restore it back to the first cloud zone as long as service levels for both cloud zones are same.  If you are deploying new applications it best to design for failure.  E.g. a distributed application running across various regions and cloud providers eliminate the need for traditional DR planning for the application as handling of failure of individual components is built in the design and deployment model of the application.

Handling Compliance in Cloud, e.g., HIPAA, PCI, SOX, SAS-70 etc.
Using available security technologies and processes several companies have implemented applications in the cloud compliant to various compliance standards, e.g. HIPAA, PCI, SOX, SAS-70 etc.  Each compliance standard has its own nuances; basically with proper planning you can address all compliance related issues.  This is a big topic on its own so please contact us if you have specific questions about this.  Cloud providers have published various case studies and best practices, e.g. white paper by Amazon on HIPAA compliance.

Handling Public and Private DNS
A common use case for enterprise applications is to have a public DNS for public access and a private DNS over internal network for accessing the backend services and databases etc.  In these situations it is best to use virtual private cloud like AWS VPC or to overlay a private network with the same IP address range as internal datacenter on any public cloud using Open Source solutions (refer to this blog - Building a Private Cloud within a Public Cloud for details on how to implement a secure private network on any public cloud).  For updating the public DNS entries for the restored application in the cloud we use DNS automation services like AWS Route 53 or EasyDNS.  Leveraging these services, Kaavo IMOD automatically updates the Public DNS for the applications as a part of the restoration during DR.

Keeping Application Database Up-To-Date
It is common for applications to have large databases.  Moving the data to the cloud and keeping it current requires first loading the entire database in cloud and then sending and merging incremental data to the database in the cloud.  To address this use case instead of maintaining a hot backup we use Kaavo IMOD to automatically bring up the database servers in cloud whenever the new incremental backup is available and merge the incremental backup then save the merged database and shutdown the servers in the cloud.  This way in case of DR we always have the latest merged database available for restoring the application. This approach provides reasonable RTO without incurring the additional costs of maintaining a hot database backup.

Applying and Maintaining Patches
A typical application requires following two types of updates during its lifecycle:

1. Updating Application Code: This is quite easy as using Kaavo IMOD we setup automation to pick up the latest code and configuration for the application from the production deployment.  This automation ensures that the application code and configuration changes for the new release of the application or service are available in the cloud for the DR.

2. OS Patches and Third-Party Software Updates: Sometimes custom patches or updates to third party software or OS are required.  For these types of changes it is best to include them as a part of change control process requiring sign-off from the team owning the DR process.  The DR team can review the change and if required make and test the needed changes to DR automation for the application.