FAQ - Frequently Asked Questions - Knowledge Base

Do all drives have to be the same model and capacity for a RAID 5 array?

The short answer is No, the drives don't have to be exactly the same.

The longer explanation is that for compatibility reasons, we usually recommend using the same model. If a certain drive is already compatible and works fine, using four of the same model will cause the least chance of running into a possible compatibility issue.

However, from the point of data security, it makes more sense to buy different models. Four drives that are exactly the same, have a higher chance of failing at the same time or at least a higher chance of two failing at the same time.

Regarding the capacity, we recommend buying drives with the same capacity. It's certainly possible to use smaller or larger drives but the total capacity will depend on the drive with the smallest capacity. This means that two 1.5TB drives and two 1TB drives, will result in about 2.7GB of actual storage capacity (4 x 1TB = 4TB - 1TB for RAID 5 redundancy and a bit less after formatting).