RAID – Data Protection or Unnecessary Expense?

In the case of servers, one mistake can turn everything upside down. Imagine a disk fails, the system stops, data disappears, and the loss counter ticks. So how do you protect yourself from such scenarios? You've probably heard many times that a RAID system guarantees security. In theory, yes, but only if you know what you're doing. RAID won't replace backups, won't protect against cyberattacks, or human errors. It's a tool that increases infrastructure resilience but doesn't make it indestructible. You still need a solid backup policy, monitoring, and awareness that even RAID has its limitations.

When is RAID worth it? It depends on the context. In databases or financial systems, there's no discussion – one downtime and clients are calling with complaints, and the company counts losses. Here, RAID is a foundation without which it's hard to imagine smooth operation. But the IT world isn't black and white. Take modern environments with Ceph or GlusterFS – here, classic RAID may be overkill. These systems can take care of data themselves, often more cleverly than a traditional array. And let's not forget the costs – it's not just about the disks, but also the controller, people's time for configuration, and subsequent maintenance. Sometimes a simpler solution turns out to be better – it all depends on what is really needed in a given environment.

RAID is often associated with data protection, but its effectiveness depends on the specific configuration – and each has its limitations.

• Take RAID 0, for example. Many are tempted by this solution because it promises great performance – after all, data is written in parallel on several disks. But there's a catch: zero redundancy. If one disk fails, you can say goodbye to all the data. Yes, there are places where RAID 0 makes sense – for example, when processing large amounts of temporary data and speed is the main concern.
• RAID 1 is much safer because it works on the principle of mirroring, but its main drawback is the double use of disk space.
• RAID 5 and 6 are popular choices in file servers and databases, but they have one critical flaw – long rebuild times after a failure.
• RAID 6 can survive the failure of two disks, but we personally believe that for most companies, RAID 10 is a better choice – it combines the performance of striping with the protection of mirroring, ensuring fast disk operations and shorter rebuild times.

So, there's no perfect solution – it's all about analyzing the load and business priorities.

This is a fundamental mistake I see too often in companies – thinking that RAID protects against data loss. RAID IS NOT A BACKUP. An array can protect against a single disk failure, but it won't protect against:

• ransomware attacks – RAID will quickly replicate encrypted data across all disks,
• human errors – if someone accidentally deletes files, RAID won't undo it,
• controller failure – if the RAID controller fails, the array may be unrecoverable.

A good backup strategy is essential. Snapshots, copies on external media, replication to another location – RAID is just the first step, but not a guarantee of data security.

The beginnings of RAID date back to times when platter drives could fail at the least opportune moment, and their speed left much to be desired. Arrays were then the golden solution to performance and reliability problems. But times have changed. Modern NVMe and SSD drives are in a completely different league – they are fast and much more reliable. Especially RAID 5 and 6 on SSD is a debatable matter – continuous parity operations can significantly shorten the lifespan of the drives. Is this the end of the RAID era? Not quite. RAID 1 and 10 are still used where data redundancy is crucial.

However, administrators are increasingly choosing more modern solutions, such as ZFS or application replication. The key is an honest assessment – does RAID really solve your problems, or is it better to look for other options?

Some RAID configuration mistakes are so common that it's hard to believe they still happen. For example, mixing disks of different speeds and capacities – this guarantees synchronization and performance problems. Another classic? Lack of monitoring the array's status. If you don't check the disks' SMART status and don't have failure alerts, you might find out about a problem only when the entire system crashes.

We've also encountered situations where administrators didn't test the RAID rebuild process, and when a failure actually occurred, it turned out the array wasn't configured correctly. RAID is not just configuration but continuous control and maintenance.

The IT world is moving forward, and RAID is no longer the only option for ensuring redundancy. In data centers, distributed data storage systems are increasingly used, where not a single RAID array but the entire infrastructure ensures reliability. Popular solutions like Ceph, GlusterFS, or Azure Storage eliminate the problem of long RAID rebuild times, allowing for dynamic data transfer between nodes. Does this mean the end of RAID? Not necessarily – in on-premise environments, it is still indispensable, but where the infrastructure allows for cloud flexibility, traditional RAID may be unnecessary.