Drives fail. This is not a hypothesis — it's statistics. The mean time between failures for server-grade hard drives runs between one and two million hours, but that's an average across an entire fleet. In practice, failures are unevenly distributed: new drives fail more often in the first months of operation, then a stable period follows, and after three to five years the failure probability rises again. If a server holds critical data with no protection against drive failure, the question isn't whether it will happen — it's when.
A hardware RAID controller on every THE.Hosting dedicated server is the first layer of data protection, built directly into the hardware. Seven locations: Finland, France, Germany, Moldova, the Netherlands, the USA, and the United Kingdom. Every server in every location ships with the controller as standard.
What RAID Is and Why It Matters
RAID stands for Redundant Array of Independent Disks. The technology combines multiple physical drives into a single logical volume with a specific data storage scheme. Depending on the chosen RAID level, it provides protection against the failure of one or several drives, acceleration of read and write operations, or both simultaneously.
The key word is redundancy. Data is stored across multiple drives in such a way that losing one — or in some configurations several — physical media does not result in data loss. The array remains operational, the operating system continues running, the administrator receives a notification and replaces the failed drive.
Hardware RAID vs. Software RAID: The Difference
There are two fundamentally different ways to implement RAID. Software RAID means the operating system manages the array, spending CPU resources on parity calculation and I/O management. Hardware RAID means a dedicated controller with its own processor and cache memory handles all of that work.
The difference shows up in several areas. The first is performance. A hardware controller doesn't burden the server's CPU with disk operations. Calculating parity for RAID 5 or RAID 6 is computationally expensive, and under heavy write loads on software RAID this becomes noticeable. A hardware controller handles it independently.
The second aspect is battery-backed cache. Quality hardware controllers include their own cache memory protected by a battery or supercapacitor. This allows the controller to acknowledge write operations before data is physically written to disk, significantly accelerating writes. If power is suddenly cut, the cache preserves its contents and completes pending operations after power is restored. Without this protection, acknowledged but unwritten data is lost.
The third aspect is independence from the operating system. A hardware controller manages the array at a level below the operating system. This means reinstalling the OS, switching distributions, or a failure at the OS level does not affect array integrity. The RAID remains stable regardless of what happens at the software level.
RAID Levels: What to Choose for a Dedicated Server
RAID 1 — mirroring. Two drives contain identical copies of data. If one fails, the second continues operating without interruption. Read speed is higher than a single drive; write speed is comparable. Usable capacity is 50% of total drive capacity. The simplest and most reliable option for storing critical data.
RAID 5 — distributed parity. Minimum three drives; data and checksum are distributed across all drives in the array. Survives the failure of one drive. Usable capacity is total drive capacity minus one. Good balance between reliability, performance, and space efficiency. Widely used for database servers and file storage.
RAID 6 — dual parity. Similar to RAID 5 but survives the simultaneous failure of two drives. Minimum four drives. Usable capacity is total capacity minus two. The choice for critical systems where the array must remain protected even while a failed drive is being replaced.
RAID 10 — mirroring plus striping. Minimum four drives; data is mirrored in pairs and distributed across pairs. Highest performance and reliability, but usable capacity is only 50%. The optimal choice for high-write-load databases where both speed and data protection matter.
Array Recovery After Drive Failure
When a drive in the array fails, the hardware controller puts the array into degraded mode. Data remains accessible — for RAID 1, RAID 5, or RAID 10, the loss of one drive does not interrupt operation. The controller logs the event, and the operating system receives a notification.
After the drive is replaced, array rebuilding begins. The controller reconstructs data on the new drive from the existing drives and checksums. Rebuild time depends on drive capacity and array load during recovery — on modern drives this takes anywhere from several hours to a day.
An important point: rebuilding is a period of elevated risk. If another drive fails during this time, for RAID 5 this means data loss. That's exactly why RAID 6 or RAID 10 is recommended for critical systems — they survive a double failure.
Monitoring RAID State
A hardware RAID controller provides tools for monitoring the state of the array and each drive individually. Most controller manufacturers — LSI, Adaptec, HP SmartArray — release command-line utilities and agents for monitoring systems.
Configure array state notifications on day one after receiving the server. Timely alerts about a drive failure give time to replace it before the situation becomes critical. RAID protects against data loss when a drive fails, but only if the administrator knows about the failure and replaces the drive promptly.
RAID Is Not a Backup
This distinction needs to be stated explicitly, because it's frequently confused. RAID protects against hardware drive failure. It does not protect against accidental file deletion, ransomware attacks, software errors, or physical disasters at the data center.
A hardware RAID controller is the first layer of protection. Regular backups to external storage are the second, mandatory layer. These two mechanisms complement each other — neither replaces the other.
Choose a Dedicated Server with Hardware RAID
FAQ
What RAID level is configured by default on THE.Hosting servers? The RAID level is configured at the time of order depending on the number and type of drives in the configuration. Clarify when placing your order — specialists will help you choose the optimal option for your workload.
Can the RAID level be changed after the server is running? Changing the RAID level requires reconfiguring the array, which typically means a full rebuild with data loss. Plan your RAID configuration at the order stage. Switching between levels on a running server is only possible after a full backup of all data.
Does RAID affect server performance? A hardware RAID controller with battery-backed cache in practice accelerates write operations compared to a single drive without RAID. Read performance with RAID 1 and RAID 10 is faster than a single drive due to parallel reads from mirrored drives.
What happens to data if the RAID controller fails? Data remains on the drives but is inaccessible without the controller in normal mode. Replacing the controller with an identical model restores the array automatically. This is one reason to document your array configuration — controller model, RAID type and level.
Does RAID replace backups? No. RAID protects against physical drive failure, but not against data deletion, ransomware attacks, software errors, or physical disasters affecting the hardware. External backups are mandatory regardless of RAID configuration.