Save Your Data

Most organizations have a haphazard backup plan or sometimes none at all, because of which they risk losing critical data compiled over months, maybe years together. You can ensure against downtime and expense of lost data by following three steps.

Identify backup needs

Begin by assessing the amount of data and its criticality. Sort through the data to identify what really needs backing up. User area and home directories on file servers usually hold documents, spreadsheets, and other files that are created and accessed daily. This volume should therefore be backed up daily. Applications and third-party software on the other hand are easier to re-install from scratch than restoring from backup. Knowing the volume of data and its criticality, makes its easier to decide on the actual medium and the frequency of backups.

Devise a backup plan

Develop a backup strategy after finding out what backup devices are available. Here it is important to consider the human and material resources to maintain the strategy. A backup plan no longer involves just copying files, but with time features such as tape tracking with write protection, cataloging and automation, and scheduling have become available. You also have to decide whether to go in for centralized storage or distributed storage. While a centralized storage strategy is easier to monitor, it has its own share of problems like increased traffic over the network. Moreover, distributed storage has become a reality with increased capacity of devices and the possibility of unattended backups. In general, centralized storage is preferred in large multi-server organizations.

Besides the transport logistics, you also have to devise a backup schedule.

This low-cost option can restore up to three days old data

A backup is classified as Incremental backup and Full System backup. Incremental backup only copies files that have changed or have been newly created since the last backup. It uses a file attribute called Archive bit to mark files as having been backed up. When the file system modifies or creates a file, the archive bit is set, indicating that the file needs to be backed up. Backup software clears the bit when the file has been backed up. An incremental backup is less time consuming and usually used for daily

backups.

Full System backups copy all server hard-disk drives every day. While these are simple to administer and restore from, they’re time consuming, thus done over weekends when network traffic is light.

Procure hardware and software

The media and backup hardware you use depend on the volume and criticality of your data. A range of backup media is available, from low-cost 4 mm tapes and quarter-inch cartridges to redundant hard disks. Third-party software products are also very popular. In addition, major OSs such as NetWare and Windows NT also have built-in utilities for automating backups.

Tape rotation

Tape rotation refers to the reusing of tape media. You can reuse tapes on a rotating basis when the tapes are so far out of date that you no longer need the data. Some organizations may need to rotate only between two tapes while others will keep backups for up to a month. To implement a fail-safe plan, you must keep a recent full system copy off-site.

Single tape cycle

This is the most basic type of backup regime you can have. It involves backing up data onto a single set of tapes and reusing them the next day. If you have a power failure at the time of backing up or if there’s some problem with the tape drive, then you are left with no fallback.

Most organizations use one of the following three tape rotation policies for their backup:

Three-tape cycle: This is another simple low-cost option, which involves using three sets of tapes for taking backups. Up to three days old data can be restored.

Here you can restore up to two weeks old data

Six-tape cycle: You need a set of tapes for each weekday from Monday to Thursday, plus two more. The four tapes are used for partial backups while the other two are used alternately for a full backup on each Friday. This way you can restore data up to two weeks old. The regime can be extended to a month by using additional Friday tapes.

This is also called grandfather-Father-Son model. It provides up to twelve weeks of backup

Ten-tape cycle: Also called the ‘Grandfather-Father-Son’ model, this scheme uses ten units of backup media (where a unit can backup the entire system) to provide up to twelve weeks of coverage. Label ten sets of media as: Monday, Tuesday, Wednesday, Thursday, Friday 1, Friday 2, Friday 3, Month 1, Month 2, and Month 3. Start the cycle on a Friday and do a full backup on the Friday 1 tape. Every Monday to Thursday take incremental backups on the appropriately labeled tapes. Each Friday, use the next Friday media set to do a full backup. Every fourth Friday, use the month tape units to do a full backup. After four months, you start re-using the tapes.