What is RAID Storage? Meaning, Types, and Working
RAID combines hardware disk units into a virtualized logical unit to improve the performance and reliability of storage.
A redundant array of independent disks – abbreviated as RAID – is a storage technology that combines multiple hardware disk units into a virtualized logical unit to improve data storage’s performance, reliability, and ease-of-access. This article explains the working and types of RAID data storage for enterprises.
Table of Contents
What Is RAID Storage?
Redundant array of independent disks – abbreviated as RAID – is defined as a storage technology that combines multiple hardware disk units into a virtualized logical unit to improve the performance, reliability, and ease-of-access of data storage.
“Redundant array of independent disks” is a form of storage that writes data to many disks in the same system. Different configurations, including RAID 0, RAID 1, and RAID 5, are stated as numbers. According to how it records and distributes your data, each RAID type offers unique advantages to its customers, including enhanced performance, higher fault tolerance, or a mix of both.
Although RAID may render company data storage more robust and reliable, it is not the same as data backup. RAID arrays distribute I/O operations over numerous disks to access and store data more quickly or replicate information on one disk across other disks, allowing the system to continue functioning sans data loss if one of the drives crashes.
In contrast, data backup allows you to recover lost files. Therefore, whereas backup and restore solutions are designed to get your systems going in the event of catastrophic loss of data, RAID is intended to prevent such loss from occurring. Similarly, although RAID makes your entire storage system more robust, it is still just a single copy of your data.
The following are concepts that are often associated with RAID:
- Striping: Data is split across many drives.
- Mirroring: Data is replicated between multiple drives.
- Parity: This is a determined number used to recreate data mathematically.
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How did RAID storage come into being?
In 1987, David Patterson, Randy Katz, and Garry A. Gibson created the phrase RAID. In their 1988 technical study titled “A Case for Redundant Arrays of Affordable Disks (RAID),” the three authors stated that such an array of affordable drives might outperform the most cost disk drives available. Using redundancy, a RAID array might be more dependable than a single disk drive.
While this article was the one to assign the notion a name, others had before proposed the usage of redundant drives. Gus German and Ted Grunau of Geac Computer Corp. first referred to this concept as MF-100. In 1977, IBM’s Norman Ken Ouchi submitted a patent for a system that was eventually dubbed RAID 4. In 1983, Digital Equipment Corporation delivered the hard disks that would ultimately become RAID 1; in 1986, IBM submitted a patent for what would become RAID 5.
While the RAID levels identified in the 1988 paper merely assigned titles to technology that was already in operation, the creation of a uniform nomenclature for the idea stimulated the data storage business to create additional RAID array solutions. Manufacturers subsequently revised the RAID term to mean “redundant array of independent disks.”
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What are RAID groups?
RAID Groups combine a collection of disks, often two or more similar units, into a single logical unit. If disks of varied sizes are connected to a common RAID Group, all disks in that group will work per the disk size with the least capacity. Likewise, if a RAID Group has many types of drives (SSD, HHD, SAS), the group will operate based on the weakest disk. Even though RAID Groups significantly improve the storage’s availability and performance, it is essential to build them depending on each group’s capacity and disk type.
To enable communication amongst servers and storage devices in the form of input/output (I/O) instructions, a LUN (Logical Unit Number) is utilized to identify the storage devices inside the RAID Group. A logical unit may consist of a single drive, numerous storage devices, a complete RAID array, or a subdivision of a single disk. Access and control rights may be assigned through these logical identities, simplifying storage resource management.
Therefore, the RAID Groups are integrated to form storage pools for improved performance and simplicity of administration. This enables enterprises to comfortably scale to meet their demands by installing disks or RAID Groups while increasing LUN storage space.
Storage pools consolidate a single or several RAID Arrays or RAID Groups that merge several kinds and sizes of hard drives into a single logical unit with a greater total storage capacity. Pools are just another RAID level that virtualizes the underlying RAID design. Pools distribute data and workload uniformly throughout the pool while extending RAID protection to the pool.
The IT infrastructure administrator may easily replace or add disks to the relevant RAID Group if a drive crashes or new drives are required. Afterward, they can dynamically redistribute the data among the pool’s current drives.
To achieve the needed level of fault tolerance, enterprises often demand unique settings for each RAID Group within their overall RAID storage architecture. These RAID combinations are referred to as RAID levels or various RAID categories.
Why is RAID storage necessary?
RAID is beneficial if you or your organization place a premium on uptime and accessibility. Backups function as an insurance policy against catastrophic loss of data. However, recovering vast volumes of data, such as when a hard disk fails, might take several hours. These backups could be worth hours or even days, losing users all the data saved or modified since the previous backup. RAID enables you to endure the breakdown of one or more hard disks sans data loss and, in many instances, without downtime.
RAID is convenient if you are experiencing disk IO difficulties, in which programs wait for the disk to complete tasks. RAID will increase performance by enabling users to access and write information from several drives rather than a single disk. In addition, when you opt for hardware RAID, it will have extra RAM for use as a cache, decreasing the pressure on the physical machine and enhancing overall performance.
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What Are The Types of RAID Storage?
Typical RAID setups are referred to as levels. There were initially five of these, but there are now many more, including many nested and several non-standard (often proprietary) levels.
As previously stated, mirroring is the duplication of data over several disks, striping is the distribution of data across multiple disks, and error correction is the storage of redundant data to enable the detection and possible repair of errors (also called fault tolerance). Depending on the system’s needs, one may use any or all of these approaches in various RAID configurations.
Varying levels have their own types of redundancy; therefore, depending on the application, a compromise involving fault tolerance and speed is often necessary. RAID 0, RAID 1, RAID 5, RAID 6, and RAID 10 are the primary RAID levels (there are others like RAID 3, which is not so frequently used). Let’s first explore these five RAID types:
1. RAID 0
RAID 0, sometimes referred to as striped set or striped volume, needs at least two drives. The disks are combined into a single big volume in which data is distributed uniformly throughout the array’s disks.
Disk striping is the technique of dividing data into chunks and writing them concurrently or sequentially on several drives. Configuring striped disks as a single partition improves speed since numerous drives execute simultaneous reading and writing operations. Consequently, RAID 0 is often deployed to increase performance.
It is the simplest and most cost-effective redundant disk design available. Nonetheless, it does not incorporate fault tolerance, redundancy, or parity in its structure. Consequently, issues with any of the disks in the array might result in a total loss of data. Therefore, it must only be employed for non-essential storage, such as backed-up temporary files.
2. RAID 1
RAID 1 is an ideal option when the main objective is data protection and redundancy. This RAID type saves your data on a single disk and a separate copy on the other available drives. This implies that you will still have access to your data even if one drive fails. This method provides a single drive’s storage space and writing performance while providing robust data security.
This is the lowest rate of RAID redundancy and is also known as mirroring since identical data is duplicated across two drives. It supports around twice the read efficiency of one drive but no enhancement in writing throughput. Data is always available as long as at least one disk is operational.
3. RAID 5
This is a popular setup that effectively balances security and performance. It needs at least three disks and provides faster reading speeds but unchanged write rates. RAID 5 adds consistency to the arrays, which occupy the space of a single disk. Additionally, this level can endure one disk malfunction. And parity checksums enable the data to be recreated in the case of a disk drive failure.
The advantage of RAID 5 is its ability to tolerate one failed disk drive. RAID 5 is hot-swappable, meaning that a disk drive may be swapped at a time the rest of the array continue to function normally. Since the parity checksums take up the space of one disk drive, the overall array storage capacity is reduced by one drive in RAID 5 deployments. RAID 5 surpasses RAID 1 and RAID 0 in fault tolerance and offers a higher overall storage capacity than RAID 1 arrays.
4. RAID 6
RAID 6 is comparable with RAID 5 only with the addition of double parity. Consequently, it is also known as a double-parity RAID. This configuration needs at least four drives. The configuration is similar to RAID 5, except two extra parity blocks are dispersed among the disks. Therefore, the data is distributed over the array using block-level striping, and two parity blocks are stored for each data block.
Striping at the block level using two parity blocks permits two disk failures before data is lost. This implies that RAID could still reassemble the data required if two drives crash. Its performance depends on the array’s implementation and the number of disks. Due to double parity, writing processes are slower when compared to other setups.
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5. RAID 10
A minimum of two RAID 1 sets are nested inside a RAID 0 setup in RAID 10. This combines performance with perhaps increased fault tolerance. Mirroring provides extra redundancy, allowing you to maintain the material regardless of whether you lose 50% of your disks – assuming your mirrored copy is not corrupted. When reliability and stability are crucial for intensive processes, corporations and other pro-units employ RAID 10.
RAID 10 utilizes logical mirroring to duplicate data across two or more disks for redundancy. If one disk fails, the data is replicated and saved on another drive. In addition, the array utilizes block-level striping to disperse data blocks across multiple disks. Since data is concurrently accessible from several drives, efficiency and reading and writing speeds are enhanced.
Another way to classify RAID is through the manner of its installation. Both software RAID and hardware RAID are available for installation, as well as an installation based on firmware:
6. Hardware-based RAID
Hardware-based RAID necessitates the installation of a specialized controller on the server. Based on the RAID configuration you select, the professionals at Steadfast will gladly offer you advice on the most appropriate hardware RAID settings that best suit your needs.
Hardware-based RAID cards manage the RAID array(s) and provide logical disks to the system without any intervention from the system itself. In addition, hardware RAID may supply the system with many RAID configurations concurrently. This contains RAID 1 arrays for the booting and app drives and a RAID 5 array for larger storage arrays.
7. Software-based RAID
Software RAID is a standard feature on almost all dedicated servers. This implies that there is NO charge for using the software RAID 1, which is strongly recommended if you employ localized storage on your machine. It is advised that all disks in RAID arrays have the same category and capacity. Software-based RAID will use a portion of the system’s processing resources to manage the RAID setup. If you intend to optimize the efficiency of a system, such as with RAID 5 or 6 configurations, users should utilize a hardware-first RAID card with ordinary HDDs.
8. Firmware-based RAID
Software-implemented RAID is rarely compliant with a machine’s boot procedure and is impracticable for desktop Windows editions. During early booting, the firmware may implement RAID, and the device drivers are initiated after the operating system is fully installed.
This technique is often referred to as “hardware-assisted software RAID” or “hybrid model RAID” since it requires little hardware assistance. This architecture has a benefit over traditional software RAID in that, in a redundancy state, the boot disk is protected against malfunctions (due to the firmware) while booting.
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How Does RAID Work?
RAID improves speed by distributing data over several drives and enabling input/output (I/O) processes to intersect measuredly. Because employing numerous drives improves the mean time registered between system crashes, redundantly storing data also improves fault tolerance. Every OS perceives RAID arrays as a single coherent disk.
RAID utilizes disk mirroring or disk striping methods. Mirroring will duplicate identical data onto many drives. Striping partitions help distribute data across several disk devices. The storage capacity of each disk is split into pieces ranging from 512 bytes to several gigabytes. The stripes of each disk are interleaved and sequentially addressed. In a RAID array, disk mirroring and striping may also be mixed.
A RAID controller manages hard disks in storage-focused arrays. Created as an abstraction layer (one of the critical components of computing and object-oriented programming) between the operating system and the actual disks, it presents groups of disks as logical units. A RAID controller might be based on hardware or software. Based on how you build a RAID, it may boost the performance of your computer and provide users with a singular ‘drive’ that can store as much data as the entire set of drives together. Alternatively, you may utilize RAID to boost dependability to ensure that your computer will continue functioning after a hard disk failure. Hybrid RAIDs enable both actions.
RAID storage isn’t a new phenomenon, but its importance has grown as organizations seek the power, redundancy, and resilience it provides. By analyzing the various RAID alternatives and their possible advantages, you may decide on the one that better matches your requirements and improves your disaster recovery approach.
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Takeaway
RAID storage can be handy for companies looking to scale their on-premise data infrastructure. Balancing your investments in cloud and disk-based storage systems is essential in an increasingly hybrid computing world. They provide the perfect mix of hardware and virtualization so that you can scale freely without compromising on control.
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