Disaster Recovery Plan (DRP)

In DR scenario operations are transferred to a remote facility to get the organization back online within recovery time objective (RTO) and recovery point objective (RPO) targets.That is how much risk business is willing to take.

Business case for having DR is Loss of revenue, competitive disadvantage, possible regulatory penalties,Legal costs.

Recovery-Time Objective (RTO): The time within which systems and applications must be recovered after an outage. It defines the amount of downtime that a business can endure and survive. Some examples of RTOs

RTO of 72 hours:Restore from tapes available at a cold site.

RTO of 12 hours:Restore from tapes available at a hot site.

RTO of few hours:Use disk-based backup technology, which gives faster restore than a tape backup.

RTO of a few seconds:Cluster production servers with bidirectional mirroring, enabling the applications to run at both sites simultaneously.

Recovery-Point Objective (RPO): This is the point-in-time to which systems and data must be recovered after an outage. It defines the amount of data loss that a business can endure.

Based on the RPO, organizations plan for the frequency with which a backup or replica must be made. Example

RPO of 24 hours:Backups are created at an offsite tape library every midnight. The corresponding recovery strategy is to restore data from the set of last backup tapes.

RPO of 1 hour: Shipping database logs to the remote site every hour. The corresponding recovery strategy is to recover the database to the point of the last log shipment.

RPO in the order of minutes: Mirroring data asynchronously to a remote site.

RPO of zero: Mirroring data synchronously to a remote site.

Return on Investment

Estimated disaster probability in a given years = 2%
Estimated cost for data loss and downtime per incident = $15 million
Probability ´ cost per incident = $300,000
Average cost of DR solution = $80,000 per year
Cost of Avoidance Savings = $220,000 per year

Ref on ROI:www.Libelle.com

  Important points to be considered for DR

• Plan , Implement and Test Disaster Recovery  - First and foremost is having Disaster Recovery plan and effective planning. Goals should be realistic for RTO, RPO and metrics.
• DR and testing should be done at application level not just individual components like Server , Storage and test DR plan at least twice in a year.
• Both failover and failback needs to defined 
     failover is how from primary site to secondary (DR site) the recovery happens
     failback :If Primary site is back to normal after disaster then how the the process of re-synchronizing that data back to the primary location from DR site , halting I/O and application activity once again and cutting back over to the original location.

• Clear defined roles , responsibilities and ownership and proper chain of command, the conditions, criteria which will triggers DR and logistics should be defined and in place before recovery process

• Focus on Business continuance and not just IT, ensuring that people and facilities are available and able to function from a business perspective. 
• Identify your most critical applications and data  and accordingly prioritize the recovery of critical applications and data.

• Perform Dry Run before actual test to provide additional information regarding any further steps that may need to be included to identify inconsistencies for correction and improvements and other appropriate adjustments and fine tuning the DR plan.

• Change management process needs to be in place to account for any changes in Production site are propagated to DR site as well.
  
  
• Automate the Recovery process as much as possible.
• Virtualise the applications and systems for simplifying the DR