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RAID and NAS are two of the most-used technologies in the field of data storage. Although RAID and NAS overlap in many cases, they are different in some fundamental ways.
How RAID configurations and NAS systems differ
First things first. Let's look at how RAID and NAS compare in the data storage landscape.
RAID, short for redundant array of independent disks, is a method of enhancing disk performance, increasing storage capacity and improving fault tolerance, depending on the RAID level chosen.
RAID enables the same data to be saved across multiple disks while still appearing as a single logical drive using specialized hardware or software called a RAID controller. RAID levels, which are denoted by a number, determine the performance characteristics of a given configuration and how much or little data protection they offer.
In RAID level 0 (zero), also called data striping, block-level data is simply distributed but not copied across multiple drives, improving performance and storage capacity but not offering enhanced protection. If one of two or more drives in this configuration fails, all data is lost.
RAID 1, on the other hand, offers a safety net in the form of data redundancy. By mirroring the contents of one drive onto another, RAID 1 ensures that data remains available should one of the drives in this configuration meet an untimely end.
Needless to say, in any discussion on RAID 0 vs. RAID 1, it's important to keep these differences in mind.
Other RAID configurations add their own benefits. For example, the popular RAID 5 configuration uses three or more drives to store data and recovery information called parity across the drives. If one disk fails, the remaining disks can keep the array going until a replacement arrives and is rebuilt.
Here we have a further look into RAID Storage Levels.
NAS stands for network-attached storage. Used by enterprises large and small, as well as in SOHO (small office, home office) environments and by creative professionals and other enthusiasts, NAS allows users to store their files on a centralized appliance or storage array.
These devices are accessible over a network using an ethernet connection and file protocols like NFS (Network File System) or SMB/CIFS (Server Message Block/Common Internet File System). Often, they contain enterprise grade NAS drives, hard drives built to withstand operating all-day, every-day, and provide better overall performance relative to their desktop counterparts.
Some sport CPUs powerful enough to allow them to run applications, security software or pull double duty as mail and multimedia servers. Others enable remote access, allowing users to access files on their PCs, phones or tablets over the internet.
NAS is a popular way of creating network file shares within an organization, where employees often collaborate on the same files or require access to records, documents and other forms of business information. It can also be used to keep a backup of files in case a local drive gives out and consolidate multimedia libraries, among other use cases where storing and trading files over a local network comes in handy.
There are a lot of factors that go into choosing the right NAS solution. They include read/write performance over a network, the number of supported users, reliability, capacity, scalability, data protection and more.
Bottom line, a lot of thought and planning goes into selecting the NAS device that works best for your business.
Where NAS and RAID overlap
Now comes the interesting part.
Some small business and most enterprise-grade NAS devices ship with RAID support. Typically, the more high-end the NAS system, the more RAID configuration options are available.
On devices designed for home or small business use, they either ship in a preconfigured state or allow users to pick from a limited number of RAID levels. High end systems for larger organizations from the likes of Dell EMC, HPE and NetApp offer a plethora of RAID options that storage administrators can use to meet their file storage capacity, performance and data protection requirements.
For example, an enterprise NAS appliance with a RAID 5 configuration will often allow users to hot swap drives. Hot swappable drives enable IT workers to remove a failed drive and replace it with a new one using specialized drive enclosures without having to shut down the system. This is useful in environments where the NAS appliance serves a mission-critical purpose and downtime is not an option.
Not an either/or proposition
As mentioned earlier, NAS and RAID are separate technologies, so you don't have to choose one over the other. They work well together or completely apart in many cases.
Home users can create a RAID setup in their own desktop PCs with the right components—no separate NAS system required. On the flipside, many NAS devices support a JBOD (just a bunch of disks) mode.
Like RAID, this mode can present multiple disks as a single logical drive, minus RAID's redundant storage capabilities. One benefit to this approach is that JBOD supports disks of various sizes, living up to its acronym by aggregating storage capacity.
For example, a three-disk JBOD setup with 1TB, 2TB and 4TB drives will have a total capacity of 7TB. In RAID configurations, it is generally preferable to use disks of the same size to maximize the amount of available capacity and avoid being hamstrung by the smallest drives, which is typically used by various RAID types to determine how they organize data across disks.
NAS and RAID performance
In a NAS solution, its performance characteristics are gauged by the components that went into it. Of course, everyone wants the biggest bang for their buck, so consider the following when shopping for a NAS system that meets your performance goals.
- CPU: Budget NAS devices will have low-end processors while enterprise NAS systems are often powered by server grade processors like Intel's line of Xeon CPUs.
- RAM: Again, home and budget NAS systems can get by with meager amounts of RAM while high-end systems can offer users dozens of gigabytes worth of memory to help speed up file operations.
- Drives: As mentioned earlier opting for enterprise, NAS-grade drives will ensure they deliver reliably fast performance with higher RPMs, which in turn offers better read/write speeds and better throughput rates. For the ultimate in performance, some vendors like Dell EMC and Synology offer all-flash NAS arrays outfitted with fast SSDs (solid-state drives).
In a RAID configuration, performance characteristics are governed by the quality and type of hard drives used, type of RAID controller and the RAID level selected. A RAID 0 implementation will deliver fast read and write speeds. RAID 5 will deliver good read speeds while write speeds suffer somewhat because the RAID array needs to store and manage parity information to provide fault tolerance, for example.
RAID or NAS?
Why not both?
If you need to provide your users with shared access to files, then a NAS in a RAID configuration is a sensible way of ensuring that hard drive failures don't put a damper on things, apart from RAID 0 setup, of course. It's practically a must in larger, shared storage environments.
Should a drive go south, critical work files remain accessible, although performance may suffer as the system compensates for the loss of a drive or if a drive rebuild is in process. And when everything is running smoothly, your users will appreciate the read performance benefits of certain configurations like RAID 1 or 10.
If you're looking for a low-cost and low-effort way to share files in a small office or workgroup, and you don't mind the prospect of losing data, then RAID is optional on your NAS, technically speaking.
Since hard drive failures are always a possibility, whether a technical fault, power surge or clumsy coworker is to blame, few storage experts advise going this route and losing valuable business data. At the very least, invest in automated backup and recovery solutions as a safety net.
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Not interested in file sharing at all?
RAID also works in workstations or DAS (direct-attached storage) devices for users seeking improved performance or data redundancy. Of course, RAID also works in SAN (storage area network) arrays, for those organizations that need to store block-based database and application data across a network.