Stop gambling with your data just because RAID sounds “too technical.” RAID (Redundant Array of Independent Disks) is the engine under the hood of your NAS that quietly decides three things: how fast you can work, how much you can store, and what happens when a drive dies. In this guide, we strip away the jargon and walk you through RAID 0, 1, 5, 6 and UDR in plain language—so you know exactly how many disks you need, what kind of speed and protection you’ll get, and which setup actually fits the way you use your NAS.

Why is it essential?

1. Fault Tolerance: Hard drives will fail. It’s not a matter of "if," but "when." RAID saves you when a drive dies.

2. Performance: It can make reading and writing files significantly faster than a single drive.

3. Continuity: You can keep working even if a drive fails.

While RAID levels show typical performance patterns (e.g., RAID 0 often provides the highest sequential throughput; RAID 1 may accelerate reads but requires mirrored writes; RAID 5/6 incur parity computation on writes), real-world performance depends on many factors. These include controller type (hardware vs. software), cache policy (write-back vs. write-through), storage media (HDD vs. SSD), interface bandwidth, stripe size, concurrent I/O patterns, workload block size, and implementation details. For performance-sensitive deployments, measure performance with realistic benchmarks for the target workload and consider cache layers or NVMe tiers to mitigate parity-related write amplification.

Don't overcomplicate it. Find your user profile below to see our recommendation.

Setting up RAID is just the beginning. Here are the honest answers to the most common (and stressful) questions users ask after the setup.

Q1: Can I change my RAID level later (e.g., from RAID 1 to RAID 5) without losing data?

A: Technically, yes, many modern NAS systems allow "Online RAID Level Migration." However, this is a very intensive process that puts heavy stress on your drives for hours or even days.

⚠️ Crucial Warning: Never attempt a RAID migration without a full external backup first. If a power outage or drive failure happens during the migration, your data could be corrupted permanently.

Q2: Can I take my RAID drives out of an old NAS and put them into a UnifyDrive NAS?

A: Generally, no. RAID configurations are software-dependent and often tied to the specific brand or controller of the original device. Moving drives between different brands (e.g., Brand A to UnifyDrive) usually requires formatting the drives, which wipes all data. You must back up your data to an external location first, then restore it to the new NAS.

Q3: If my NAS breaks, can I just plug the RAID hard drives into my Windows PC to read them?

A: No, you cannot simply plug them in and view files in Windows Explorer. Most NAS devices use Linux-based file systems (like EXT4 or Btrfs) and complex RAID structures that Windows cannot natively read. You would need specialized (and often expensive) data recovery software to attempt this. The safest path is to insert the drives into a compatible NAS unit from the same manufacturer.

Q4: If a drive fails and I only have one left, can I save my data?

A: It depends entirely on your RAID level:

• RAID 0: No. If one drive dies, all data is gone.

• RAID 1 / 5 / 6 / UDR: Yes. The system is designed to run in "degraded mode." You can still access your files, but you should replace the failed drive immediately to rebuild the array before another drive fails.

Q5: What is the absolute 1 thing I must do before creating a RAID array?

A: Verify your drives. Before filling them with data, run a "Health Check" or S.M.A.R.T. test to ensure the drives don't have bad sectors. Using an old, failing drive in a new RAID array is a recipe for disaster. And remember: RAID is not a backup. Always keep a separate copy of your most critical files on a different device or cloud service.