DEVELOPMENTTECHNOLOGY
Whether it’s to optimize a server’s performance or prevent total data loss on a NAS (Network Attached Storage) box, you need RAID. But which RAID type is right for you? Here is a guide for new storage users.
If you’ve ever researched the purchase of a NAS device or server, you’ve undoubtedly come across the term RAID (Redundant Array of Independent Disks). Generally, a RAID system uses two or more hard disks to improve performance or provide fault tolerance in NAS and servers. Fault tolerance means setting up a secure structure to ensure that a machine with a failed hard disk will continue to run smoothly. Fault tolerance reduces operational downtime and also reduces the chance of data loss.
Fault tolerance is configured according to RAID levels. The RAID level is decided based on the number and type of disk storage devices, the importance of recovery for data needs, and the importance of high performance. An enterprise is generally more concerned with maintaining data integrity in hardware failure than a home user.
RAID Overview: What is RAID?
RAID is used in businesses and organizations where disk fault tolerance and optimized performance are necessary. Servers and NAS in enterprise data centers typically have a piece of hardware called a RAID controller. Depending on the RAID configuration, these systems have several SSD or SATA disk drives. Due to the increasing storage demands of consumers, home NAS devices also support RAID.
Software RAID means you can set up RAID without needing a dedicated RAID controller. RAID capacity is built into the operating system. You can set up a single disk with two partitions, one for preloading and one for data storage.
This RAID is available in operating systems, including OS X servers, Linux, and Windows servers. Software RAID also includes virtual RAID solutions sold by service providers to provide robust host virtual RAID converters. This is a more entry-level solution for enterprise networks.
Which RAID is right for me?
As we mentioned earlier, there are many levels of RAID, and which one you choose depends on whether you use RAID for performance, fault tolerance, or both. It also matters whether you have hardware or software RAID. Also, the type of controller is essential when you use hardware RAID. Different controllers support different RAID levels and determine the types of disks you can use in sequence: SAS, SATA, or SSD.
Popular RAID Levels
- RAID 0 improves the server’s performance, known as “disk partitioning.” When using RAID 0, data is written over many disks. This means that the computer works with more than one disk instead of one, improving performance. This is because more than one drive reads and processes data, improving disk input/output. It needs at least two disks. Both software and hardware RAID support RAID 0, as do many controllers. The downside is that there is no fault tolerance. If even one of the disks fails, the whole array is corrupted, and there is a high probability of data loss or increased corruption.
- RAID 1 is known as disk mirroring with fault tolerance configuration. With RAID 1, data is seamlessly and continuously copied from one disk to another, thus providing a replica or twin structure. If one disk fails, the other can continue to work. This is the easiest way to utilize fault tolerance and is also cost-effective.
- The downside of RAID 1 is that it leads to a decrease in performance. RAID 1 is available via software or hardware. A hardware implementation of RAID 1 requires at least two disks. With the software RAID 1, instead of two physical disks, data can be copied on a disk partition on a single disk. Another point to remember is that RAID 1 divides the disk capacity in half. If a server with two 1TB drives is configured with RAID 1, the total storage capacity will be 1TB, not 2TB.
- RAID 5 is the most common configuration for enterprise servers and NAS devices. This RAID level provides better performance than RAID 1, i.e., mirroring. With RAID 5, data is partitioned across three or more disks. If a disk fails or starts to fail, the data is automatically and seamlessly recreated from this distributed block of data and parity. The system continues to work, even with one disk, until you replace the failed drive.
- Another benefit of RAID 5 is that it allows many NAS and server drives to be hot-swapped. So if a drive in the array fails, you can replace it with a new drive without disrupting access for users accessing the server or NAS and without shutting down the server or NAS. This is an excellent solution for fault tolerance. Because when a drive fails, the data is recreated on the new disks while the failed disks are replaced.
- The downside of RAID 5 is the performance hit where servers perform many write operations. For example, RAID 5 on a server with a database that many employees access during the working day can have a noticeable lag.
- RAID 6 is widely used in enterprises. It is almost the same as RAID 5, but RAID 6 is a more resilient solution. Because it uses multiple parity blocks compared to RAID 5, two of your disks can die, but your system will still work.
- RAID 10 is a combination of RAID 1 and 0. It is commonly referred to as RAID 1+0. It combines the mirroring of RAID 1 with the partitioning of RAID 0. It is the best-performing RAID level but is also more expensive than others. It requires twice as many disks as the other RAID levels, at least four. This RAID level is ideal for highly utilized database servers or hardware that performs many write operations. RAID 10 can be implemented as hardware or software, but the performance advantages are lost when using it.
Other RAID Levels
Other RAID levels are also available. Example: 2, 3, 4, 7, 0+1, etc. These are variants of the actual RAID configurations mentioned above and are used for specific operations. Here are brief descriptions of these levels:
- RAID 2 is similar to RAID 5, but the partitioning occurs at the bit level instead of disk partitioning by mirroring. RAID 2 is rarely used because it is generally costly to implement and performs poorly in some disk input and output operations.
- RAID 3 is similar to RAID 5, but this solution requires a specialized parity drive. RAID 3 is rarely used except in highly specialized databases or processing environments.
- RAID 4 is the configuration where disk partitioning is at the byte level instead of the bit level, as in RAID 3.
- RAID 7 is a proprietary RAID level owned by an organization that is no longer on the market.
- RAID 0+1 is often confused with RAID 10, but they are not the same. RAID 0+1 is a twin array of partitions with a RAID 0 layout. It is used for specific infrastructures that require high performance but not high scalability.
For many small and medium-sized business purposes, the performance of RAID 0, RAID 1, RAID 5, and in some cases, RAID 10 is sufficient. For many home users, RAID 5 can be overpowered, but RAID 1 provides good fault tolerance with disk mirroring.
Finally, we should note that RAID is not a standalone backup solution and cannot replace a backup strategy. RAID provides excellent benefits for optimizing NAS and server performance and quickly recovering from hardware failures. But it can only be one part of a complete disaster recovery solution.
