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Data Protection and Disaster Recovery

Impact of Disasters

With the proliferation of e-business, an enterprise today operates in an extremely complex and a highly networked, global economy, and is more susceptible to interruptions than in the past. The cost of such interruptions, or downtimes, varies across industries and for companies with a significant web presence, this cost can be as much as millions of dollars in an hour. Market research from Oracle's own customers confirms this general trend. A large company in the hotel industry is an Oracle customer. It offers an online Hotel Reservation System, for which the cost of downtime amounts to $100K an hour. For another customer which operates a semiconductor manufacturing plant, the cost is equivalent - at $25K an hour per FAB, with 4 FABs at the site.

While these numbers are staggering, the reasons are quite obvious. The Internet has brought millions of customers directly to the electronic storefronts. Critical and interdependent business issues such as customer relationships, competitive advantages, legal obligations, industry reputation and shareholder confidence are even more critical now because of their increased vulnerability to business disruptions and downtimes.

Importance of Data

A business may suffer downtime that can be both unplanned and planned. Unplanned downtimes may be caused by hardware or system failures, data/storage failures, human errors, computer viruses, software glitches, natural disasters and malicious acts. A business may also have to undergo planned downtimes because of scheduled maintenances such as system upgrades or data transformation. 

Any business designing its business continuity strategy must create a business continuity plan (BCP) that can effectively deal with each of these challenges and protect its assets. The primary assets needed to effectively operate a business are:

• facilities
• hardware
• network
• data

In the event of a disaster, hardware and networks can be replaced, and facilities can be moved to a new location. However, data is the most critical asset of the business - whether it is payroll/employee information, customer records, valuable research, financial records, historical operations information, etc. If a business loses its data, it cannot be replaced, and rebuilding/regenerating that data will likely be an extremely expensive, if not an impossible task. A company that has lost its business data will find it very hard to remain in business. This is particularly true considering that Federal/SEC regulations mandate companies (esp. financial institutions) to retain their business critical data for a minimum number of years. Thus, one of the underlying foundations of a BCP is that it must offer protection of company data.

Data Protection Strategies

Given the importance of data protection, a myriad of technology solutions exist today to enable businesses protect their data, and recover the data in a timely manner as and when needed. Some of the solutions available today are:

• Backup and Recovery - A well-designed and well-integrated Backup and Recovery strategy, without data loss, is a must for every database deployment. Effective backup strategies usually include local and remote copies of data, full and incremental backups, online backups, support for desired secondary devices (e.g. hi-speed tape, disks), off site tape archiving, etc.

• Snapshots - Snapshots are images of all or part of a disk filesystem that are taken periodically and stored in another disk allocation. Thus, in the event of a database corruption, rather than going back to the previous night's tape backup, the DBA may resort to the earliest snapshot in which the corruption does not exist. 

• RAID (Redundant Array Of Inexpensive/Independent Disks) - The fundamental principle behind RAID is the use of multiple hard disk drives in an array that behaves like a single large, fast one. There are many different ways to implement a RAID array, using some combination of mirroring, striping, duplexing and parity technologies. The degree of benefits using RAID depends on the exact type of RAID that is configured, but RAID generally provides some combination of these benefits: higher data security, 
  fault tolerance, improved availability, increased and integrated capacity and improved performance. 

• Remote Data Mirroring - In Remote Data Mirroring, data is replicated between a primary and a remote secondary storage subsystem by sending track-by-track changes from the primary site to the remote site over a secure network. In the event of an outage or a disaster, the database may be restored and recovered at the mirrored site, and systems may then point to this mirrored site and continue operations. 

• Data Replication - In contrast to remote data mirroring, Data Replication is a software-based solution that copies data from the primary database to one or more secondary databases. These multiple databases together constitute a distributed database system. Transactions can be replicated continuously or on a scheduled basis. Replication usually involves some strategy to resolve conflicting transactions that appear on the same dataset but in different databases.

• Automated Standby Databases - Automated Standby Databases are an effective means for disaster recovery by providing a completely automated framework to maintain transactionally consistent copies of the primary database. Changes can be transmitted from the primary database to these standby databases in a synchronous manner - enabling zero data loss, or in an asynchronous manner - minimizing any potential performance impact on the production system. This technology also provides an automated framework to switch over to the standby system in the event of a disaster or a corruption on the production site, or even during planned maintenances.

With so many solutions available, and considering that these solutions can be combined with one another, the technologies that a business ultimately chooses depends on its business requirements. Answers that this business must determine before embracing any technology are:

• What is its cost of downtime?

• What is the anticipated data growth for this company?

• What data needs to be protected?

• What type of disasters/downtimes should the company be most concerned with?

• What is its Recovery Time Objective (RTO) - i.e. the tolerable maximum length of time that the business can be unavailable?

• What is its Recovery Point Objective (RPO) - i.e. the maximum amount of data the business can afford to lose?

• What is its current networking/communication infrastructure, and what are the future networking requirements?

• How best can it leverage existing system resources - i.e. can the company leverage existing capabilities within its hardware and software infrastructure, or is it better off buying and integrating best-of-the-breed solutions?

For example, if the company's RTO is zero or very near to zero (e.g. a stock exchange), then relying on just backup and recovery is not an option - because in the event of a disaster at the primary site, a secondary site must be restored and brought up with previously backed-up data and the business will be unavailable during that time. Similarly, if a company has already invested in appropriate software infrastructures, it makes sense to leverage the disaster recovery capabilities of that software (e.g. Oracle 9i Database), instead of investing in newer remote mirroring technologies. If a company has to protect both database-resident data and filesystem-resident data, and both these types of data change frequently, then a combination of remote mirroring and automated standby databases, along with usual backup and recovery strategies, may make more business sense.

The great thing about using Oracle as the underlying technology foundation for high availability (HA) and disaster recovery (DR) is that the Oracle database natively offers most of the popular HA/DR solutions available today. When used in combination with partner-technologies that have been validated with the Oracle database, customers will have a complete portfolio of HA/DR solutions to choose from that will best fit their business requirements. 

Click here for an overview of the data protection and disaster recovery solutions available from Oracle.