Due to the fact that most RAID drives have a built-in redundancy and mirror data across hard drives, people often assume their data is completely protected. Unfortunately that isn’t true, and there are still risks to data on RAID drives that you need to be aware of.
First and foremost you should always remember that the redundancy in RAID drives exists to protect it from the risk of a single hard drive failing. But there are other risks that RAID drives do not (and cannot) protect against, such as:
- File deletion
When a file is deleted on a RAID drive, that deletion is immediately mirrored across all hard drives in the RAID – meaning that the file will be gone and cannot be restored by rebuilding the RAID. Other data recovery methods will need to be used, and may be successful if the data isn’t overwritten.
It is worth noting that file deletion can be accidental, or it could be caused by bugs or malware and viruses that wipe out some files.
- Corrupted data
If a file on a RAID drive is corrupted, the corrupted data will be replicated across the RAID and rebuilding it will not fix the data. Sometimes (but not always) corrupted data can be recovered using recovery software, but it is generally best to restore it from a backup.
Typically data can be corrupted by viruses or malware, or it may be an early sign that a hard drive is starting to fail. As a rule it is better to be safe rather than sorry, and replace a hard drive in a RAID that starts to contain corrupted data.
- Fires, floods, theft and other threats
Due to the fact that the RAID drive is in a single location, it is exposed to various threats such as fires, floods, theft, and so on – all of which could compromise its data. If the RAID drive is damaged some data may be recoverable depending on the extent of the damage – but if it is completely destroyed or stolen then all data will be lost.
- Multiple disk failures
As mentioned previously RAID drives are designed to have a redundancy in case a single drive fails. However if multiple drives fail that redundancy will not suffice, and data will be lost. The risk of multiple disk failures is higher than most people realize because RAID drives often consist of identical hard drives that were manufactured in the same batch. Because of that as the hard drives age the risk of them failing at around the same time is high.