What you need to know about setting up RAID on your NAS

A redundant array of independent disks (RAID) helps to protect network-attached storage (NAS) and other devices against data loss when multiple drives are used. A bunch of drives can be brought together on a NAS to create a single volume or storage pool. This makes it easier to work with data across multiple devices. A RAID achieves the same result but has the bonus of redundancy through reserved bacup data and drive failure tolerances. Combining a NAS with RAID is an easy way to create a powerful, yet user-friendly storage solution for the local area network (LAN).

What is RAID?

RAID is a feature supported by most (if not all) NAS operating systems enabling you to clone data across multiple drives. Split into three aspects, RAID can help you shield yourself against data loss through data striping, mirroring, and parity. Striping data involves splitting blocks into smaller blocks and storing them on separate disks. Mirroring is cloning data from one drive to another, and parity involves adding error correction codes to stored data. Although RAID should not be considered a data backup, it will help avoid losing data from the inevitable failure of one or more of your drives.

Why should you use RAID with NAS?

A NAS typically has more than one drive installed inside the enclosure. These can be joined together to create a single storage pool where data can be stored from multiple clients, but to help with combating potential drive failure, we’ll need a RAID. No drive will last forever, even an SSD. Mechanical drives have many moving parts that are all potential failure points. Should a drive fail in your RAID, the OS will be able to recover by taking recovery data and rebuilding the RAID using a replacement drive. Depending on the RAID used, you’ll have a fail tolerance of at least one drive.

The process of creating a RAID on your NAS will be similar regardless of the manufacturer and OS. If setting up a new NAS, you’ll configure the drives through the installer and if adding new drives after installing the OS, it’s usually handled through the drive management app. Once up and running, you’ll barely notice it’s there. Again, depending on the RAID you select, you may lose storage space since part of the storage pool will be used to store recovery data. This could be an entire drive or two, so plan accordingly to ensure you have ample space.

Different RAID types

RAID 1 is the most basic form of RAID. Also known as mirroring, data is duplicated across all drives. An entire drive is reserved for parity, slashing the overall capacity of the pool by half. This does provide the quickest recovery should a drive fail. RAID 1 is better suited to smaller NAS deployments with two drives. For more than three drives, I’d suggest moving up to RAID 5 or 6. With a drive fail tolerance of one and two, respectively, they’re ideal for those with lots of data to store on NAS. Parity data is stored on a drive, which is then used to rebuild the RAID should one fail. RAID 1+0 is essentially RAID 0 and RAID 1.

Regardless of which RAID you choose (other than RAID 0 or JBOD) you will sacrifice some storage capacity for drive redundancy. RAID can also affect performance since the drive will handle parity and thus write speeds will be slightly reduced.

Using RAID does not back up your data

I keep hammering on about this point, but it’s vital you understand that using RAID does not mean you’re backing up data. Yes, your RAID may be able to automatically recover from a drive failure and not lose a single byte of data, but there’s always a risk of something happening to the RAID that could cause files to become corrupt or lost. Data can become corrupted through firmware failures or system glitches. The RAID will not be able to recover the data without relying on a backup for reference. There’s even the possibility of the RAID controller failing.