The distributed computing environment at Clemson University allows employees to have much more flexibility in managing their computer information. However, everyone needs to be aware of the need to protect valuable data that may no longer reside in the data center.
The Clemson Computing & Information Technology (CCIT) goes to great lengths to protect the data stored on its servers. There are scheduled processes to make backup copies of all of the data on the various computing servers. The areas where the data is stored have elaborate security, environmental and power control and fire protection. Backup data is stored at multiple locations to prevent a disaster at one site from destroying all copies of data files. If you choose to place your data on one of the CCIT servers, your data will be protected for you.
However, there may be valid reasons to store University data on non-CCIT servers or even on a personal computer or workstation. If you do choose to store data on these other computers, you need to be aware of the conditions which may cause data to be lost and take the necessary precautions to prevent the data loss.
The common causes of data loss are:
- an equipment failure, power outage
- a software problem
- lightning
- just plain old human error.
Any of these problems could cause the data stored on a disk drive to be deleted or become unreadable. If your data is lost, it will be, at best, a time consuming process to recreate it and, at worst, the data will be lost forever. Therefore you need to make regular backup copies of your data. This is especially important after major changes. You will want to pattern your backup procedures to match the way your data changes. The more the data changes, the more often it needs to be backed up. If data is accidentally deleted, you need to notify the person(s) responsible for backing up the data. Human errors of this type are undetectable to the backup process and data may be permanently lost if it is not recovered within a complete backup cycle.
There are three major types of backups: full, incremental and differential. In a full backup, all of the data is copied. This process takes the longest time and requires the most backup media, but it is often the easiest method to restore lost data. Incremental backups only copy the data that has changed since the last incremental backup. This method takes the shortest time, but is the hardest to restore data because all incremental backups since the last full backup must be applied to restore the data to the most current state. Differential backups copy all the data which has changed since the last full backup. This is a compromise procedure which simplifies data restores at the price of increased backup time over incremental backups. Only the last differential backup need be applied to the last full backup to restore the data to the most current level.
After backup is complete, the copy of the data needs to be stored in a safe location. It is dangerous to store the backups in close proximity to the data being backed up. If you have your backups stored in your office with your PC a small fire or water leak could destroy everything. Moving the backup data to another room or another building will increase the probability of the data surviving a small disaster. If the data is very valuable, you may want to store the backups off campus to help guarantee their survival in the event of a larger disaster.
Care must be taken when moving backups to remote locations. Most backups are made using magnetic tape or removable magnetic disk (“floppy disk”). This media is easily destroyed by things common to our everyday environment, heat, moisture, chemicals and magnetic fields. Disk and tape can be immediately damaged by any of the following:
- Touching the recording surface with your fingers or anything else
- Bending the disk or tape
- Writing on a “soft” disk with a ball point pen or pencil
- Spilling coffee, soft drink or other substances on the disk or tape
- Overheating the disk or tape (leaving it in the hot sun or near a radiator)
- Exposing the disk or tape to magnetic fields (telephones, electric motors, TVs)
Disk and tapes will deteriorate due to wear from use and exposure to high humidity or dust. If tapes or disks begin to have errors or show any signs of physical defect or wear, they should be replaced. Recordable Compact Disks (CDs) are starting to be used for backups. These disks are immune to magnetic fields and less susceptible to humidity, but care must still be taken not to damage the recording surface.
Sometimes data is no longer needed for current business operations, but it is required by law or policy to be kept or “archived” for some period of time. This data is usually moved from expensive hard disk drives to a less expensive form of storage. Additional care must be taken with archived data. Magnetic media stored in a clean, dry area free from magnetic fields and static electricity will last many years. However, the equipment used to read the data may become obsolete during that period. It may be necessary to periodically copy archive data to newer media or store it on microfiche or paper if it is to be kept for long periods. The University Records Management Office should be contacted for policies on data retention and archiving assistance.
