Guide
Why a RAID or mirrored drive setup is not a backup
Mirrored or redundant drive setups get mistaken for backups constantly, because they do genuinely protect against one specific kind of failure while doing nothing against several others.
What redundant drives actually protect against
A setup that keeps data mirrored across multiple drives protects against one of those physical drives failing — the data simply still exists on the others, with no interruption.
What it does nothing about
Delete a file, and it disappears from every mirrored drive simultaneously, since mirroring copies changes instantly and exactly. The same is true of accidental overwrites or file corruption introduced at the source.
A real backup still needs to exist separately
Redundant drive setups are genuinely useful for uptime and protection against hardware failure, but they are not a substitute for a separate, independent backup that can recover from a mistake rather than only a broken drive.
Questions people ask
Does a mirrored drive setup protect against ransomware-style file corruption?
No — corruption or malicious changes get mirrored just as instantly and faithfully as any legitimate change.
Is it still worth using a redundant drive setup at all?
Yes, for the specific protection it offers against drive hardware failure — it is simply not a replacement for a true backup.