RAID Calculator — Usable Capacity & Rebuild Time (RAID 0/1/5/6/10)

How to choose the right RAID level?

There is no single best RAID level — the right choice depends on how much you value capacity, performance, and protection, and on how many drives you have. Below is a plain summary of where each level fits. RAID 0 — striping RAID 0 spreads data across all drives with no redundancy. You get the full combined capacity and the best raw speed, but zero fault tolerance: if a single drive fails, the entire array is lost.

RAID 5 vs RAID 6: which should you choose?

This is the most common decision for anyone building a multi-drive array, and the answer has changed as drives have grown larger. RAID 5 costs you one drive of capacity and tolerates one failure. RAID 6 costs two drives and tolerates two failures. On paper RAID 5 looks more efficient, and with small drives it is a perfectly reasonable choice. The complication is the rebuild window.

Real-world capacity planning: how much space do you actually need?

Capacity planning is where most home and small-business RAID builds go wrong. Either the array is undersized and needs replacing in eighteen months, or it is drastically oversized and money that could have gone into a better backup strategy sits in unused terabytes. Getting this right requires thinking about growth, not just current needs.