Network Storage Backup & Restore

Analysts have considered all the costs and come up with some figures:

$50,000 is the average hourly cost per megabyte to re-create and restore data. $18,000 is the average hourly cost of downtime for PC networks. Then there is the cost of downtime. The out-of-pocket expenses associated with downtime hide a wealth of other costs, including loss of customers and impact on an enterprise's reputation and image. The average cost of downtime ranges from approximately $90,000 per hour of in the transportation industry (airline reservations) to $6.5 million for large brokerage houses in the finance industry (as reported by Contingency Planning Research). Clearly, data protection is business protection. Especially today, when business has become so dependent upon information.

The Solution

"People don't plan to fail; they simply fail to plan."

Backup: Your First Layer of Protection

An effective backup process, however, requires more than a single layer of redundancy on a single type of media. Here are some hints in creating an effective backup process.

1. Create a multi-layered backup schedule.

It takes many copies of files stored on separate pieces of media--in separate locations--to fully ensure that data is protected. You need to develop a multi-tiered backup system with a well-defined policy for media rotation.

Most files don't change from one day to the next, so most companies don't need to back up every file every day. Three different backup levels are commonly used:

Full backup -- usually includes the entire system and all its files.

Incremental backup -- includes only the files that have changed since the last full backup.

Differential backup -- includes every file that is new or has changed since the last full backup.

Within any of these three levels, either individual file or disk image methods can be used for backup (image backups take a snapshot of your entire disk and send it to tape).

2. Rotate the media according to a well-defined schedule.

Media rotation is an important part of a layered backup schedule. Two media rotation schemes are commonly used to provide a comprehensive backup program: the Grandfather-Father-Son schedule, and the Tower of Hanoi scheme.

Grandfather-Father-Son: This scheme uses daily (Son), weekly (Father), and monthly (Grandfather) backup media sets. Four backup media set are labeled for the day of the week each backs up; for example, Monday through Thursday. Typically, incremental backups are performed on the Son media, which is reused each week on the day matching its label. The Father media is reused monthly; and the Grandfather media records full backups on the last business day of each month. Each of these media may be a single tape or a full set of tapes, depending on the amount of data you need to back up.

Tower of Hanoi: This scheme uses more media sets than the grandfather-father-son technique for increased safety. One media set A is used every other backup session; the next media set B starts on the first non-A backup day and repeats every fourth backup session. Media set C starts on the first non-A or non-B backup day and repeats every eighth session. Media set D starts on the first day when there is no other backup session and repeats every 16th session. Media set E alternates with media set D.

Thus, the most frequently used media sets have the most recent copies of a file, while less frequently used media retain older versions.

3. Don't skimp on media quality.

Losing data is expensive. Purchasing high-quality backup media is not. We recommend that you invest in high-quality, high-capacity tape for your servers. Choose a product with proven performance and durability as well as high capacity.

Sun offers Sun-qualified media through eSun for all of Sun's removable media storage products.

4. Handle media with care.

Your best-laid backup plans won't do much good if the backup media isn't cared for properly. Never wait for the system to reject your media; follow these guidelines to ensure your media won't fail:

Inspect media for damage BEFORE use Acclimate media before use Store media in specially designed racks and storage boxes Write-inhibit the media before long-term storage or data interchange Conduct periodic clinical cleaning of the storage areas Observe media labeling recommendations Monitor system and performance records Secure and control access to the media.