In today's world of information and technology, data is the most powerful tool one can have. Over the years the operational importance of data in business has grown substantially. Also with the use of Internet and computers, the amount of data involved has grown exponentially. New data-centric applications and tools ,like online transaction processing, decision-support, data warehousing, and data mining and analysis have been developed. Moreover, operational data in many organizations is in use on a 24 hour by 365 days per year basis. These factors in combination to network computing, a variety of computing platforms, very large databases, and mission-critical operations, make data protection both more complex and more crucial. Small and medium-sized businesses are most at risk from data loss because of their limited resources. Therefore, a proper data backup and recovery plan is necessary to ensure that the critical data is protected at all times.

Data loss is one of the most misunderstood of all the computing concepts. Very little information has been made public about data loss and the information that does exist is inconsistent. This may cause confusion among the users because the industry often presents "lost data" as data that has been permanently destroyed, with no hope for recovery. Due to the mixed messages they receive, users find it difficult to properly evaluate their data loss situations and make educated decisions to recover from them. Despite technological advances in the reliability of magnetic storage media, the incidence of data loss continues to rise. Data storage remains a fragile science, and data's susceptibility to damage from both natural and human sources remains high.

Hardware or System Malfunction
Most of the data losses (more than 40 percent) are caused by the malfunctioning or some technical problems with hardware or system. These causes include power failure, head or media crash, controller failure, etc. Symptoms of such a loss are as follows:

• Error message stating that the device is not recognized

• Previously accessible data is suddenly gone

• Scraping or rattling sound

• Hard drive may not spin

• Computer or hard drive does not function

Human Errors
Carelessness on part of users and other human errors are often a major cause of data loss. These errors include accidental deletions, mistakes on part of MIS department and administrator, etc.

Viruses and Other Malicious Attacks
Viruses, worms and trojans are another common cause of data loss. Data loss is the biggest concern when dealing with viruses and other malicious attacks. Some viruses are simply an annoyance while others can damage or even delete the data.

Natural Disasters
While floods, fires and hurricanes have visible symptoms, lightning strikes and brownouts often leave no clue other than that one would not be able to access data that was previously there.

Data Backups and Recovery

The only way to prepare is to back up all of your data.� Put it on a disk or two or three.� Heck, you may want to make back-ups of the back-ups.� You may even want to re-create the backups from time to time.  And even with the best of care, disks can get dirty, develop viruses and otherwise just stop working.� So that is then the key, BACK IT UP.  For more information about backing up your data, please see Chapter 10.

1.  Put everything in one folder.

Put everything in one folder -- all of your pictures, all your word documents, all your spreadsheets, everything.� This way, when you back up your files, all you have to copy is one folder.� Bookmarks and games can not be stored in the documents file, so make sure to back up that type of information too.  In addition to documents, spreadsheets, and pictures, etc you should also back up system files.� It will save you from having to reinstall windows when your computer crashes.� Also, remember all those CD"S that came with your printer and all the software and games?� Keep those.� If your computer ever crashes you will need those to get yourself up and running again.

2.  Back this data onto 2 or 3 diskettes.

There are several options available to you that you can use to back up your computer.� One of the most popular ways is to use the Iomega zip drive.� A zip disk can store 100 MB of info and are a lot more resilient to damage then a standard 3.5 inch diskette.� Another good method to back up files is by using a CD.� Blank CD's are relatively inexpensive, and CD burning technology seems to get cheaper by the day.� CD's can hold a lot of information and are relatively impervious to dust and heat.� If you have music or pictures, a CD might be your best storage option.�

3.  Store backup disks in a secure location.

Securing valuable information through regular backups is the best defense against a natural disaster, a runaway virus, or a hack job. When implementing a backup policy, don't forget to also secure the backup media. For example, if one regularly backs up critical data files and then tucks the media away in an unsecured desk drawer, you are inviting theft. At a minimum, store backup media in a secure environment. 

4.  Use offsite backups in case of disasters.

It is also recommended that a second set of backup media be periodically archived in a secure remote location.

5.  Store backup tapes away from large metal objects to avoid damage from magnetic fields causes in lightning strikes.

6.  Have a written disaster recovery plan

This plan should outline your plan of action in case of natural disaster which destroys hardware and renders the room which stores the machine unusable.  Have this plan in case the worst happens.

Regular data backups are very necessary for businesses because of three reasons.

Firstly, due to the general characteristic of physical failures is that the data becomes immediately inaccessible and must be recreated on new or different hardware. Constituting this are hardware failures, typically in the form of a disk-head or media failure, unrecoverable hardware errors and physical disasters ranging from power surges to earthquakes, floods, sabotage, etc. The most desirable outcome is to be able immediately to recreate the data in the state it was in the instant just before the physical failure.

Secondly, due to the logical failures caused by errors or defects in the application program or underlying software, data entry errors, and so on. The media containing the data remains operational, and it may be that only a fraction of the content is incorrect. The most desirable outcome is to be able immediately to change the data to the state it would have been in had the error not occurred. In other words, remove the effects of the error. Because often significant amounts of correct work have been done between the time the logical error occurred and its detection, the ideal solution would re-process this work instantaneously against the correct data content.

Finally, because of the needs for archival storage to allow old data or older versions of current data to be retrieved. Reasons for doing this include: responding to audits, re-creating an inadvertently deleted file, gathering historical data for a new data warehouse application, retrieving records associated with a particular project, customer, user, and so on.

Data Backups

Backup is the act of copying files to a second medium such as a diskette, zip drive or tape, as a precaution in case the first medium (hard disk) fails. A copy of files maintained on a second medium (a disk or tape) as a precaution in case the first medium fails. Data backup provides ways to protect data in case of a physical problem with the computer system such as a hard disk failure or power failure. It is vitally important to back up of software and key files since even the most reliable computer is apt to break down eventually. There are many techniques for backing up files depending up on the type of data, convenience of the recovery process, etc. The basic types of backups that can be performed are:

Normal or Full backups: All files that have been selected are backed up, regardless of the setting of the archive attribute. When a file is backed up, the archive attribute is cleared. If the file is later modified, this attribute is set, which indicates that the file needs to be backed up. In this type of back up, it's easy to find files when required. Since full backups include all data on the hard drive, one doesn't have to search through several disks or tapes to find the files to restore. But there is a drawback with the full backups that they are redundant backups. Since most of the files on the system rarely change, each backup following the first is mostly a copy of what has already been backed up. Also full backups take longer to perform and can be very time consuming.

Differential backups: Designed to create backup copies of files that have changed since the last normal backup. The presence of the archive attribute indicates that the file has been modified and only files with this attribute are backed up. However, the archive attribute on files isn't modified. This allows the user to perform other types of backups on the files at a later date. In comparison to the full backups, the differential backups take lesser time. Hence, it provides more efficient restores. However, differential backups are also redundant backups. Each day's backup would store much of the same information plus the latest information added or created since the last Full Backup.

Daily backups: Daily backup is designed to back up files using the modification date on the file itself. If a file has been modified on the same day as the backup, the file will be backed up. This technique doesn't change the archive attributes of files.

Offline and Online backups

Once the backup mode is chosen, another question to be addressed has to do with the length of time the data is inaccessible because of the backup. This time is called the backup window. In the past, because most applications did not run 24 hours a day, seven days a week, backups were typically run at night and/or on the weekends. Lately, more and more applications are approaching full 24 hour operation, every day of the year. This means that the backup window must be made as small as possible. There are two approaches to minimizing the backup window. The first is to bring the application down for the duration of the backup and do the backup so quickly that the time taken from the application is negligible. Bringing the application down or quiescing it is generally required to ensure that the application data is in a defined state. One way to achieve a very short backup window is to have an extra mirror that is disconnected after the application is stopped. Then the application is quickly restarted. This so-called coffee-break window essentially spins off a point-in-time copy of the data that can either be maintained as a separate mirror or used as the source of a point-in-time backup to tape, or both.

The backup approach described above is essentially an off-line backup in that the application must be off-line to insure data integrity for the duration of the backup. Some application software and most data base managers have specific interfaces defined for use by backup programs to support data integrity for a point-in-time backup while the application continues to run its normal function. This is called an on-line backup. In some cases the data is backed up as the application runs creating what is called a fuzzy backup (because the data is in a somewhat undefined state). While a fuzzy backup is being created, some applications build a journal of changes to be recorded with the application to facilitate returning the fuzzy data to a defined state. The Oracle database manager on various UNIX platforms supports backups done this way, for instance.

Logical vs. Physical Backup

One special consideration about direct backup should be taken into account. Since the data storage system generally deals with physical elements such as blocks, tracks, cylinders, and disks, the direct backup would deal only with these physical elements unless some special provisions are made. On the other hand, because the data is read on the application host in the local and network backup approaches, the backups easily deal with logical elements such as files, tables, indexes, catalogs, and the like.

Dealing with logical elements when doing a direct backup requires that the physical location of the logical elements be determined and made known to the backup server. This job is eased if the backup server runs data access software identical to that in the application hosts. However, when there are multiple application hosts to back up that are different in one aspect or another, a more creative solution is required.

Backing up the Backup

Since backup systems are part of the overall protection for a company's operations, it is worth looking at backup in this broader context. Simplistic approaches often lead to taking unnecessary or ineffective measures. For instance, some installations have a "no single point of failure" policy for high availability systems. Applying this policy to the disk subsystem leads to the conclusion that it is necessary to use duplicate, mirrored disks (or some other form of RAID providing redundancy). However, if one was to apply the policy to the individual disks again, he would wind up mirroring the mirrors, and so on. Obviously, no one would ever really do this, but there have been cases where this type of logic has been applied to the backup subsystem. Clearly, there are elements of a backup system that should be protected from a single point of failure. However, it should always be kept in mind that ultimately a set of tapes representing a backup are essentially a mirror of the data.

To maximize data availability and minimize the possibility of lost data, it is necessary to look at the overall installation. Probabilities should be assigned to the various types of failures that can occur. Then, all of the protection mechanisms, each with its own particular time to effect recovery and its own probabilities for failure, can be added to the equation to determine the overall expected data availability and the expected down times when there is a failure. In this way, the most effective places to apply additional redundancy and/or increased performance resources for recovery can be determined.

Data Backup Tips

• Back up data and test restore capabilities on a regular basis. Verify that the correct data is backed up.

• Keep computers and other equipments in a dry, controlled environment that is clean and dust-free.

• Only entrust data to someone who has the training and expertise to properly maintain and repair it.

• Use diagnostic and repair utilities with caution. Never use file recovery software if one suspect an electrical or mechanical drive failure.

• Use anti-virus software and update it from time to time.

• Check all incoming diskettes for viruses. This includes packaged software, software carried on-site by users and software downloaded via modem, bulletin board services or the Internet.

• Never attempt to operate a visibly damaged hard drive. Do not use any storage device that has been exposed to heat, moisture or soot.

• Do not shake or remove the covers on hard drives or tapes.

• Immediately turn off the computer if it begins making an unusual noise. Further operation may damage it beyond repair.

Data Safety

There are other specific items left to deal with in protecting computer data besides keeping data from the eyes of unethical immoral people -- that of machine failure.  Computers crash.� Especially when you least want them to, like when you have a big project due or an important email that needs to be responded to immediately.� It seems that Murphy's Law is the only law that holds any sway when it comes to your computer's hard drive.� Unlike other issues discussed in this book, there are no common sense approaches to keep it from happening, no programmers out there hard at work trying to protect your computer from crashing.� There aren't even any hackers or attackers to blame.� The fact is that human beings are fallible and so are the things they make and therefore, hard drives are not perfect.� Just like you would never expect to drive a car without it breaking down once in a while, so you should expect and learn to deal with crashing hard drives.

A.  Make an Emergency disk

There are several very important things you can do to protect your hard drive, the most important being: back up all your data regularly, keep your computer in a cool environment, make an emergency bootable floppy disk, keep a fire extinguisher nearby, and keep programs to a minimum, uninstalling those you don't use, monitor and regulate the power supply and restrict authentication and access to your computer(s).

Say your hard drive crashes or your PC will not boot for whatever reason (probably because you have something important to do), you will need a bootable floppy disk.  See this page on how to do this correctly.

B.  Have a Disaster Recovery Plan

In today's interconnected economy, organizations are more vulnerable than ever to the possibility of technical difficulties disrupting business. Disaster recovery has taken on a new sense of urgency in recent years. Emerging issues like terrorism, hackers, computer viruses, an increased reliance on computers, and the increasing occurrence of emergencies and disasters have all led to an increased need to prepare for disasters that can affect the availability, integrity, and confidentiality of critical business resources. Disaster recovery planning is the technological aspect of business continuity planning. Disaster Recovery can be defined as the ability to respond to an interruption in services by implementing a disaster recovery plan to restore an organization's critical business functions. It incorporates not only planning for any imaginable type of disaster that may hinder the operations of a business, but also putting measures in place to avoid such disaster altogether. Disaster might be something huge like an earthquake or the terrorist attacks on the World Trade Center (that affected everything from telephones to the New York Stock Exchange) or something comparatively small like system/software failure caused by a computer virus. Disaster recovery strategies can include the use of alternate sites, redundant data centers, disaster insurance, business impact analyses and legal liabilities.

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