So I fell into a storage rabbit hole today — and somehow, it was actually… fun? 😅
Let me introduce you to RAID — a word that sounds like a boss fight but actually stands for Redundant Array of Independent Disks.
Basically, RAID is what you use when:
- You want your data to survive a hard drive dying (RAID 1 vibes)
- You want things to be super fast (RAID 0 zoom zoom)
- Or you’re an enterprise sysadmin trying not to lose 10TB of customer data on a Monday morning
In this post, I’ll explain how RAID works, break down the most popular types — RAID 0, 1, 5, 6, 10, and 01 — and when you’d actually use them.
📦 What Is RAID (Actually)?
RAID combines multiple physical drives into one logical volume to improve performance, fault tolerance, or both.
There are two main types:
- Hardware RAID — handled by a dedicated controller
-
Software RAID — managed by the OS (e.g. Linux
mdadm, ZFS, or Windows tools)
Different RAID levels give different trade-offs. Let’s go through the main ones:
⚡ RAID 0 – Striping
Performance only, no redundancy.
RAID 0 splits ("stripes") your data across two or more drives. So if you’re saving a file, part of it goes on Disk A, part on Disk B, and so on. This makes read/write speeds super fast because the system can access data from multiple disks at once.
🚨 But: there's no backup. If even one disk fails, you lose everything — because no disk holds the full picture.
👩💻 Use it for: scratch disks, temporary files, gaming PCs scratch disks, temporary files, gaming PCs
🛡️ RAID 1 – Mirroring
Redundancy, but no performance boost.
RAID 1 copies ("mirrors") the exact same data to two or more disks. So every file you save is written identically on all drives in the array. If one disk dies, the other(s) have your back.
Performance isn’t better than a single disk, but reliability is great.
👩💻 Use it for: small business servers, boot drives, anything critical
⚙️ RAID 5 – Striping with Parity
Balanced performance and fault tolerance.
RAID 5 splits your data across all drives (like RAID 0), and also calculates a special bit of data called parity. That parity info is spread out too, and can be used to rebuild data if one disk dies.
It needs at least 3 disks: two to hold data, one for parity (though the parity is distributed). Reads are fast, and writes are decent.
🕳️ Write Hole Warning:
RAID 5 can suffer from something called a write hole, where the data and its parity get out of sync due to an unexpected power loss or system crash during a write. This can cause corruption that RAID can’t fix. Some systems mitigate this with battery-backed cache or journaling.
👩💻 Use it for: NAS systems, mid-size production servers NAS systems, mid-size production servers NAS systems, mid-size production servers
🧷 RAID 6 – Striping with Double Parity
Like RAID 5, but safer.
RAID 6 is just like RAID 5, but instead of one parity block, it uses two. That means it can survive two disk failures instead of one.
This adds more fault tolerance but slows down write performance a bit since more calculations are needed.
👩💻 Use it for: critical storage where uptime matters critical storage where uptime matters
🔀 RAID 10 (1+0) – Mirror + Stripe
Fast and fault-tolerant.
RAID 10 first mirrors your data (like RAID 1), then stripes it (like RAID 0). So you get the best of both: redundancy and speed.
It needs an even number of disks, minimum 4. If one disk in each mirrored pair fails, you’re still safe. But if both disks in a mirrored pair fail, then 💀.
👩💻 Use it for: databases, high-load systems databases, high-load systems
🧩 RAID 01 (0+1) – Stripe + Mirror
Similar to RAID 10, but riskier.
RAID 01 stripes first, then mirrors. So you create one striped set of drives (like RAID 0), and then clone that entire set onto another.
Sounds similar to RAID 10, but it’s more fragile: if one drive in the stripe fails, the whole stripe is lost — meaning one entire half of the mirror is gone. One more failure, and you’re done.
👩💻 Use it for: legacy setups (but RAID 10 is usually better) legacy setups (but RAID 10 is usually better)
That’s it for my RAID brain-dump! Hopefully now if someone says "RAID 10 is better than RAID 01" you’ll actually know why 😌📀