Free Files and disks lessonsFiles and disks · Stage 2 · Reliability · Step 1

RAID

Combine several disks for speed and survival: striping, mirroring and parity, and what each costs. About 13 minutes.

Quick check

Five disks of 2 TB are set up as RAID 5. What is the usable capacity?

Show the answer

8 TB. One disk's worth goes to parity: (5 − 1) × 2 = 8 TB.

Lock it in

Short questions that apply the idea to new cases: trace it, work out a number, put steps in order. A wrong answer explains itself.

Answer them in your browserFree account, no card. Your progress is saved, and the idea comes back in a quick review later.