Security Database integrity Database integrity is a central underlying issue in the implementation of database technology. Trust in the Correctness of the data that is held by the database system is a prerequisite for using the data in business, research and decision making applications. Data base Integrity refers to the trustworthiness of system resources over their entire life cycle.
[In a database system, a method to ensure data integrity is fundamental to providing database reliability and security. In particular, as data is communicated or distributed over networks, a method to validate information as authentic is required. The value of a database is dependent upon a user’s ability to trust the completeness and soundness of the information contained in the data]
Three basic types of database integrity constraints are:
• Entity integrity
• Domain
• Referential integrity

Integrity means that the data will be safe and will not be subject to changes wither they were initial or accidental. There are many, many causes that change data over time such as human error, system malfunction ect. Integrity keeps the data intact and in its original form.

Disk Storage Systems
“Disks can fail when a single bit or few bits will flip. This problem can often be detected and corrected at the hardware level by using error correcting codes in the embedded system of the drive”. It can also happen at the software level.
RAID Disk Technology
The one way to prevent data corruption or data lost due to a hard drive is to have in place a RAID. [The design of RAID technology has allowed improvement in storage performance, reliability and recovery. The levels of RAID organization divide the disks into reliability groups with each group having extra check disks containing redundant information. When a disk fails, the assumption is that within a short time the failed disk can be replaced and the information can be reconstructed on the new disk using the redundant information.]
RAID
• level 1 mirrors each disk with a full image copy. Every write to a disk is also a write to a check disk. Although the check disk can be used to improve read performance, this is a costly option • level 2 bit-interleaves the data across the disks in a group and adds enough check disks to correct a single error.
• level 4 was designed to bring down the cost of small disk transfers by striping the data across the array at the sector level instead of at the bit level. This reduces the write access requirement to two disks, a data sector and the parity sector from the check disk.
• Level 5 improves upon level 4 by distributing the data and the check information by sectors over all of the disks in a group. This design improvement allows for all of the disks in a group to be used to distribute the data access load and removes the bottleneck of having only a single check disk. • Level 6 adds an additional set of parity information on each drive. This allows a RAID 6 array of disks to recover from two simultaneous disk failures for a critical application. This level cost in performance.
Raid can defiantly be the backbone for your business’s data integrity. They can be costly, but worth it. This level really is not supported by most hardware
• Level ten (also known as RAID 1+0) is one of the newest levels and is the most used for today’s standards. Storage In the pc market raids are not an option, because this would cause the price to increase for the overall system by hundreds of dollars. So people have started to use offsite storage which can be cheaper than buying the same amount of storage in multiple drives.
Tools for Backup and Recovery
“In a production environment, there are many strategies at the database level that are recommended as best practices to maximize the availability of a database.”
(see report on “Backup Disaster Recovery”)
Checksums and Secure Hash Algorithms
[Checking the integrity of the information in the storage system is essential. The use of checksums is a well-accepted way of ensuring data integrity. Checksums may be able to detect data corruption due to a hardware malfunction that could otherwise go unnoticed and cause further damage. They are routinely used to validate data that must travel over network links.] This is just another way to protect data, by doing this you keep everyone happy.
Cyclic Redundancy Check
“A cyclic redundancy check is a type of hash function that leaves the data intact and appends a checksum to it.” It is importantly used in network traffic because the addressees of the message can easily recomput the checksum to check the accuracy of the data received. Just like registered memory. The memory checks the data in and data out.
Secure Hash Algorithms
[A hash function H is a transformation that takes an input x and returns a fixed-size string called the hash value. In cryptography and in the government standards for secure hash functions, the requirements are more strictly defined as:
• ß The input can be of any length.
• ß The output has a fixed length.
• ß H(x) is relatively easy to compute for any given x.
• ß H(x) is one-way.
• ß H(x) is collision-free. A hash function is “one-way” if you begin with a hash value h, it is “computationally infeasible to find some input x such that H(x) = h”.]
Security
“System integrity, security, and recovery go hand-in-hand. The use of data integrity assurance techniques can enhance the security of computer systems.” In this day and age Security seems to be one of the main focuses and with good reason, with all the id theft and the oh so many ways in which it is pulled off.
Conclusion
[The value of a database is dependent upon a user’s ability to trust the completeness and soundness of the information contained in the data. It is the database administrator’s responsibility to choose wisely from the available tools to safeguard the data integrity.] Database integrity problems can have many sources:
Hardware malfunctions, software bugs, malicious attacks, or user errors. There are current tools available to avoid, detect, and correct these problems. There is ongoing research to further improve the choices.
“The relational model enforces referential integrity. That means you must enable your system's referential integrity feature to meet relational rules. Often, it is as simple as just enabling referential integrity between tables.”

References
Contributor, G. (n.d.). Ensure data integrity with proper database design | TechRepublic. TechRepublic - A Resource for IT Professionals. Retrieved February 29, 2012, from http://www.techrepublic.com/article/ensure-data-integrity-with-proper-database-design/5034793
Social network sites: Definition, history, and scholarship - AcaWiki. (n.d.). Home - AcaWiki. Retrieved February 21, 2012, from http://acawiki.org/Social_network_sites:_Definition,_history,_and_scholarship

http://www.thegeekstuff.com/2010/08/raid-levels-tutorial/
http://www.cs.iusb.edu/technical_reports/TR-20071226-1.pdf