RAID 0 vs RAID 1: speed and space, or a safety net?
Choose RAID 0 only for replaceable data where speed and capacity matter and loss is an inconvenience, not a disaster. Choose RAID 1 for data you can't afford downtime on — a single mirrored pair is the simplest way to keep working through a drive failure. For most people storing anything important, RAID 1 (or a parity array) is the right default.
The most opposite pair in storage: all performance versus all protection.
RAID 0 and RAID 1 are the two simplest arrays, and they sit at opposite ends of the trade-off. RAID 0 stripes data across both drives for double the capacity and roughly double the throughput, but a single drive failure destroys the entire array. RAID 1 mirrors the same data onto both drives, so you keep only one drive's worth of space but survive a complete drive failure with zero data loss.
By TechCompare · Updated
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Same 2 × 4 TB drives, each scheme
Two 4 TB drives under each scheme. RAID 0 doubles your space and speed but tolerates zero failures; RAID 1 halves your space to keep a full mirror that survives a drive dying. Neither replaces a real backup.
RAID 0
Usable capacity
of 8 TB raw
Storage efficiency — 100%
Fault tolerance
None — any drive failure loses the array
RAID 1
Usable capacity
of 8 TB raw
Storage efficiency — 50%
Fault tolerance
Survives 1 of 2 drives failing
Capacity and fault tolerance only — rebuild risk and write performance also depend on drive size and controller.
Side-by-side specs
| Spec | RAID 0 | RAID 1 |
|---|---|---|
| Minimum drives | 2 | 2 |
| Usable capacity (2 × 4 TB) | 8 TB (better on this spec) | 4 TB |
| Storage efficiency | 100% (better on this spec) | 50% |
| Drives tolerated lost | 0 | 1 (better on this spec) |
| Read performance | ~2× single drive | Up to ~2× (either disk) |
| Write performance | ~2× single drive (better on this spec) | ~1× single drive |
| Rebuild on failure | Impossible (data lost) | Copy from mirror (better on this spec) |
| Risk profile | Doubles failure risk | Halves downtime risk (better on this spec) |
| Replaces a backup? | No | No |
| Typical use | Scratch / cache / games | Boot mirror / small NAS |
How they differ
With two 4 TB drives, RAID 0 gives you 8 TB usable and near-double sequential read/write, which is why it's used for scratch disks, video editing caches, and game libraries where the data is replaceable. RAID 1 gives you 4 TB usable and reads can be served from either disk (a read speedup), but writes happen to both so write speed is unchanged. The critical point both share: RAID is not backup. RAID 0 has zero redundancy, and even RAID 1 won't protect you from accidental deletion, ransomware, or a controller failure that corrupts both mirrors. A 3-2-1 backup is still mandatory either way.
Verdict
With two 4 TB drives, RAID 0 gives you 8 TB usable at near-double sequential read and write speed, which is exactly why it suits scratch disks, edit caches, and game libraries. RAID 1 halves that to 4 TB but reads can be served from either disk (a small read speedup) and a complete drive failure costs you zero data. The killer detail neither side escapes: RAID is not a backup. RAID 0 has zero redundancy, and RAID 1 won't save you from deletion, ransomware, or a controller fault that corrupts both mirrors, so a 3-2-1 backup is mandatory under either.
Size a RAID 0 or RAID 1 arrayWhich should you pick?
Choose RAID 0
Pick RAID 0 for scratch drives, editing caches, OS-level temp space, or game installs — anything you can re-download or regenerate. Never put irreplaceable files on RAID 0.
Size a RAID 0 stripeChoose RAID 1
Pick RAID 1 for a small always-on server, a home NAS holding documents and photos, or a workstation boot mirror where surviving a drive failure without downtime is worth giving up half the raw capacity.
Size a RAID 1 mirrorRelated comparisons
Frequently asked questions
Does RAID 0 actually double your drive performance?
Is RAID 1 a substitute for a backup?
When does RAID 1 win over RAID 0?
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