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RAID and Backup

RAID 0, 1, 5 and 10 protect against a failed disk; backups protect against everything else. You need both.

What Is RAID?

Full, incremental and differential backups
Full, incremental and differential backups

A widely used rule for important data: Keep 3 copies of your data (the original plus two backups), on 2 different types of media (for example the server's disks and a cloud service), with 1 copy off-site (somewhere else, so a fire, flood or theft cannot destroy every copy). Test your backups by restoring a file now and then. A backup that cannot be restored is useless.

Practice

A small office needs a server that keeps working if one disk fails and uses as much of the disk space as possible. It has four disks. Which RAID level fits best?

What Is RAID?

RAID Is Not a Backup

Types of Backup

Full, incremental and differential backups
Full, incremental and differential backups

The 3-2-1 Rule

A widely used rule for important data: Keep 3 copies of your data (the original plus two backups), on 2 different types of media (for example the server's disks and a cloud service), with 1 copy off-site (somewhere else, so a fire, flood or theft cannot destroy every copy). Test your backups by restoring a file now and then. A backup that cannot be restored is useless.

Practice

A small office needs a server that keeps working if one disk fails and uses as much of the disk space as possible. It has four disks. Which RAID level fits best?