Data Protection and Recovery

Good practices should always be followed to protect data integrity in the physical environment include: making servers accessible only to network administrators, keeping transmission media (such as cables and connectors) covered and protected to ensure that they cannot be tapped, and protecting hardware and storage media from power surges, electrostatic discharges, and magnetism. Data integrity can also be threatened by environmental hazards, such as

• heat
• dust
• electrical outages and
• power surges.

However, humans may also come into play and delete data by accident, or otherwise remove important data.

Importance of Backups

Backup is the activity of copying files or databases so that they will be preserved in case of equipment failure or other catastrophe. For personal computer users, backup is also necessary but often neglected. Backing up to a Tape drive, Zip drive, Jaz, Syquest, or to a hard disk.

Once a week or so, you should back up your files (at least your own data files and perhaps the entire contents of your hard drive) to an alternative storage device. Many people neglect this task, and live to regret it later.

Data Restoration

The retrieval of files you backed up is called restoring them. Backing up to a Tape drive. Backing up usually takes a while (about several hours minutes for the contents of a 80 gig hard disk or array). There are also easily removable drives that you can back up to, especially if you have other reasons to use these (for example, for large graphic images that you store offline).

Physical Loss Prevention Measures

High Availability Power Supply
The power supply(s) in the server has to be able to provide a lot more power than a regular computer power supply A redundant power supply normally consists of two or three hot-swap power supplies in one unit that continuously supplies power to the server. In the event of a power supply failure, the other power supply unit(s) will handle the full load. The defective power supply unit can then be replaced without turning off the server. There is typically an audible alarm that alerts you that one of the power supplies is not functioning. Redundant power supplies offer one other important feature, two power cords. If the cords are plugged into different power sources, you can even survive a tripped breaker or a cord accidentally disconnected.

Hard drive redundancy
Hard drives are more resilient and help to save data when they are in a RAID set. Many motherboard companies provide a SCSI host adapter on the motherboard. Each SCSI host adapters can control up to 15 hard drives allowing room for expansion.

RAID
RAID is a technology that allows us to arrange multiple hard drives together to provide fault tolerance as well as very large logical drives. The idea of fault tolerance allows us to have a single hard drive failure without causing the server to fail. Here are two examples of RAID:

RAID 1 or Mirroring is where we take two hard drives of the same size and mirror all information on both drives. If either one of these drives fail, the system will keep going.

RAID 5 or Striping with parity allows us to take a number of smaller, less expensive drives and make one large drive where you can have any single drive in the array fail, without your server failing.

Tape Drives
Tape backup is your last line of defense in the case of disaster. Some of the tapes should be stored off site in case of a disaster like fire or flood. Studies show complete loss of data from a disaster is enough to put many companies out of business. This can be even more costly if the data you lose belongs to someone else.

Geomar Computers
5980 Fairmount Avenue Suite 111
San Diego, CA 92120
(Mission Valley)

• 619-283-2364
• Fax 619-283-2364

Web site: www.geomarcomputers.com
email: service@geomarcomputers.com 

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