A RAID array is built to survive a drive failure, which is exactly why a RAID failure can be so confusing. The server is still running, or it was until a moment ago, and it’s tempting to start swapping drives and clicking “rebuild.” That’s the moment when most RAID data is actually lost.
If your array is degraded, offline, or showing errors, here’s what to do first.
1. Stop and don’t rebuild yet
A rebuild reads every sector of every remaining drive. If a second drive is weak (and drives in the same array are often the same age and model), the rebuild can push it over the edge. At that point, many RAID 5 arrays can’t recover on their own. If the data isn’t fully backed up, don’t start a rebuild until you’ve secured a copy.
2. Don’t initialize, re-create, or “force online”
Options like “initialize,” “create new array,” or forcing a failed drive back online can overwrite the configuration or data that recovery depends on. If the controller offers to do any of these, cancel.
3. Label every drive and write down its position
Before removing anything, label each drive with its slot or port number. Drive order matters to a RAID, and mixed-up drives are one of the most common reasons a simple recovery becomes a hard one.
4. Write down what you know about the setup
- RAID level (0, 1, 5, 6, 10, etc.)
- Number of drives, and which one failed first
- Controller or NAS model (for example Dell PERC, HP Smart Array, Synology, QNAP)
- Operating system and file system
- What happened just before the failure: power outage, update, error messages
This information can save hours in a recovery.
5. Don’t run file system repair tools
Tools like fsck or CHKDSK try to “fix” a volume by rewriting its structure. On a damaged array, they can scramble data across all the drives at once.
6. If the data is still accessible, back it up first
If the array is degraded but still readable, copy your most important data to a separate device before replacing the failed drive or starting a rebuild. Start with what you can’t replace.
7. Keep the original drives together
Don’t reuse, reformat, or return any drive from the array under warranty until your data is safe, including the one that failed. A professional recovery may need every drive.
RAID is not a backup
RAID protects you from one drive failing. It doesn’t protect you from deleted files, ransomware, controller failure, or two drives failing at once. Once your data is safe, set up a separate backup.
Disklab recovers data from failed RAID arrays, NAS devices, and servers, including virtual machines stored on them.
When to call a professional
If you’re not sure whether your situation is safe to handle yourself, stop and ask. A quick conversation costs nothing and can keep a recoverable problem from becoming a permanent one. You can read how we work on our data recovery process page.
Need help now? Start a recovery case or call us at 1-844-347-5522.