What is the main drawback of mirroring in RAID?

The primary drawback of mirroring in RAID is that it requires more storage, making it expensive. Mirroring involves creating an exact copy of the data on multiple drives. While this provides excellent redundancy and data protection—ensuring that if one drive fails, the data remains accessible on another—the downside is that the total usable storage capacity is effectively halved. For instance, if you have two drives with a combined capacity of 2TB, the usable storage for the data will only be 1TB since both drives contain identical data. This increased demand for storage space can raise costs significantly, as more drives need to be purchased to achieve the same storage capacity. Consequently, any organization considering a mirroring RAID setup must factor in these additional costs as a fundamental drawback compared to other RAID configurations that use less storage overhead.