RAID 5 vs RAID 10: capacity efficiency or rebuild safety?
Choose RAID 10 for anything write-heavy or latency-sensitive — databases, VM stores, busy file servers — and wherever fast, safe rebuilds matter. Choose RAID 5 when capacity per dollar is the priority and the workload is read-mostly, ideally on drives 8 TB or smaller. For larger drives, many people skip RAID 5 entirely in favour of RAID 10 or RAID 6.
The classic NAS fork: one more drive of space, or faster and safer rebuilds.
On a four-drive array of 8 TB disks, RAID 5 gives you 24 TB usable (three drives' worth) by storing distributed parity, while RAID 10 gives you 16 TB (two drives' worth) by striping across two mirrored pairs. RAID 5's appeal is capacity efficiency; RAID 10's appeal is dramatically better write performance and a fast, low-risk rebuild that simply copies from a surviving mirror instead of recomputing parity.
By TechCompare · Updated
Try this comparison with our tools
Same 4 × 8 TB drives, each scheme
Four 8 TB drives under each scheme. RAID 5 nets you a full extra drive of space (24 TB vs 16 TB) via parity; RAID 10 trades that capacity for parity-free write speed and a rebuild that just copies a surviving mirror.
RAID 5
Usable capacity
of 32 TB raw
Storage efficiency — 75%
Fault tolerance
Survives 1 drive failure
RAID 10
Usable capacity
of 32 TB raw
Storage efficiency — 50%
Fault tolerance
Survives 1 drive per mirror pair (1-N depending on which fail)
Capacity and fault tolerance only — rebuild risk and write performance also depend on drive size and controller.
Side-by-side specs
| Spec | RAID 5 | RAID 10 |
|---|---|---|
| Minimum drives | 3 | 4 |
| Usable capacity (4 × 8 TB) | 24 TB (better on this spec) | 16 TB |
| Storage efficiency | 75% (4 drives) (better on this spec) | 50% |
| Drives tolerated lost | 1 | 1 (up to 2 if not same pair) (better on this spec) |
| Write performance | Parity penalty | Excellent (no parity) (better on this spec) |
| Read performance | Fast | Fast |
| Rebuild method | Recompute parity (slow) | Copy mirror (fast) (better on this spec) |
| Rebuild risk on big drives | Significant (URE) | Low (better on this spec) |
| Scales by | 1 drive (better on this spec) | Pairs of 2 |
| Best for write-heavy / VMs | Weak | Best (better on this spec) |
| Best for capacity per dollar | Best (better on this spec) | Weak |
How they differ
The rebuild behaviour is the heart of the decision. RAID 5 rebuilds by reading every remaining drive in full and recomputing parity — slow, I/O-heavy, and risky on large modern drives where an unrecoverable read error during the rebuild can kill the array. RAID 10 rebuilds by copying a single surviving mirror, which is far faster and far less stressful on the array. RAID 10 also has much better random and sequential write performance because it never computes parity. The cost is capacity: RAID 10 always gives up half the raw space, and it scales only in pairs. RAID 5 squeezes more usable terabytes from the same bay count but pays for it in write overhead and rebuild risk.
Verdict
On four 8 TB drives, RAID 5 nets 24 TB usable against RAID 10's 16 TB, so RAID 5 wins the capacity-per-dollar row by a full extra drive. RAID 10 wins almost everything else: writes are parity-free so they hit single-drive speed, and rebuilding a failed drive is just copying a surviving mirror instead of recomputing parity across the whole array. That rebuild is fast, low-risk, and immune to the URE problem that haunts large-drive RAID 5 arrays. RAID 10's cost is giving up half the raw space, which is why it dominates databases and VM stores where uptime matters more than terabytes.
Compare RAID 5 vs RAID 10 capacityWhich should you pick?
Choose RAID 5
Pick RAID 5 for read-mostly bulk storage — media libraries, archives, backups-of-backups — where getting the most usable terabytes from your bays matters more than write speed, and your drives are 8 TB or smaller.
Size a RAID 5 arrayChoose RAID 10
Pick RAID 10 for databases, virtual-machine datastores, video capture, and any busy multi-user server where write performance and a fast, low-risk rebuild justify giving up half the raw capacity.
Size a RAID 10 arrayRelated comparisons
Frequently asked questions
Why does RAID 10 have better write performance than RAID 5?
Which is safer to rebuild, RAID 5 or RAID 10?
When is RAID 5 still the right choice over RAID 10?
Related tools
RAID Calculator
Calculate usable capacity and fault tolerance for RAID 0, 1, 5, 6, and 10.
Use tool ➜Data Transfer Calculator
Estimate transfer times for files over USB, WiFi, Ethernet, and more.
Use tool ➜Power Cost Estimator
Estimate annual electricity costs for your PC, Server, or TV.
Use tool ➜Memory and Storage Latency Visualizer
Visualize the massive speed difference between CPU cache, RAM, and storage.
Use tool ➜