An introduction to tape backupIf you run your own business, think about how you're saving your important files. Chances are you're saving them to a central server... maybe a Windows 2000, 2003 or XP server, or Apache/Linux. But what are you doing to ensure your files won't be lost in the event of a fire or other disaster? What many people fail to realise is that while you can insure your premises and equipment, you can't insure files. You can't buy back or repair lost files. Ipso facto, they are lost! You should be thinking about implementing a disaster recovery plan for your business. Disaster recovery is about safeguarding all critical files and data so that they can be recovered in the event of a fire or other disaster. For many businesses, this may include Exchange Server and SQL Server files as well. What you have to do is ensure that all files on the server are backed up to another storage medium (tape, removable hard disk, NAS device, etc.). Most businesses choose to use tape. Let's look at how you can set up a tape backup strategy for your own business. Tape.. the perfect backup mediumIsn't tape an anachronism in the age of optical disks, removable hard drives and a plethora of whiz-bang, random-access storage media? Tape is indeed a dinosaur in relative terms, but it's ideal for backup. Tape is slow, but can store a lot of data... one mid-range tape should be enough to backup your entire server. Plus, tape is extremely cheap - mid-range tapes cost around $20 each. When should you backup?Typically, server backup is performed at the end of each day. Just put in the tape and let the backup process run overnight. If your server ever suffers a catastrophic disaster, you have at least saved all your files from the previous day. Tape RotationThe ideal tape backup solution would involve using a new tape for each backup. This means purchasing a new tape for every day of your business's operations. This is hardly cost-effective for your business. Tape is cheap, but not that cheap! This is why we speak of "tape rotation". Tape rotation means to reuse tapes from previous backups. The simplest tape rotation scheme is to have one tape for each day of the working week. Tapes are labelled: Monday, Tuesday, Wednesday, Thursday and Friday. You can restore data from any one of the tapes in your library - or in this case, any day in the past the week. This strategy requires only five tapes, but only provides one week's data backup history. Grandfather-Father-Son - A Case StudyThe grandfather-father-son schedule is the most widely used method, and involves backing up data in the following way:
This system is far more powerful than the five-tape rotation, but requires more tapes. This strategy provides you with the ability to restore data from the last week, plus any Monday over the last month, plus any month for as many monthly tapes as you have. Variations on this scheme are available, and provide a trade-off between the number of tapes required, and the number of monthly tapes available. Different types of backupDifferent types of backups are available in backup software.
A Full backup will copy all files and system data to the backup media. It allows for the complete restore of all data from one single tape. Differential, Incremental and Daily are partial backups are designed to reduce amount of data backed-up to the media, resulting in faster backups. To restore data using one of these backups, the last Full backup tape will also be required, along with any other partial backups since the last Full backup.
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