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What is RAID 5 and how is it used?

What is behind the RAID 1 hard drive array?

After being first described in 1987, the concept of merging storage media in a so-called RAID is still important decades later. For example, RAID 1 or RAID level 1 is still in demand as a storage solution for server applications today: The hard disk combination provides the proper level of security that high-availability software requires. What makes a RAID 1 system so secure, and what exactly is RAID 1?

What exactly is RAID 1?

RAID 1 is a storage security standard that aims to increase data security. The concept relies on a group of two or more hard drives that stores all data in mirrored form, or in duplicate, to achieve this purpose. The core feature of RAID 1 is data mirroring, commonly known as "mirroring." In a RAID 1 setup, all files created and saved on disk 1 are also written to disk 2 or all other disks, giving the system total redundancy in the specified factor: If one disk fails, the next one automatically takes over.

The storage quota of the smallest installed disk determines the maximum capacity of a RAID-1 array, or RAID level 1.

Controlling more than one hard disk during the read process and comparing the read data streams with each other can be added to the security if the RAID controller (in the case of a hardware RAID) or management software has a matching function. When there are disparities, the system generates an error, allowing early detection of hardware faults. In this instance, though, the system's performance suffers marginally. The read speed is another area where the suitable functionality of the control instances can help: Similar to a RAID 0 array, the RAID 1 system accesses multiple hard drives during the read phase and then reads in different sectors of these disks in simultaneously. This method, for example, can double the output performance of two linked disks.

A RAID (Redundant Array of Independent Disks) is a collection of at least two distinct storage media that work together to form one huge logical drive. The relevant hard disk installations, which are defined in RAID levels such as RAID 1, determine the concrete function. The main points are data security and increased data throughput.

With the exception of the minimum of two disks, there is no limit or specification for the number of storage media in a RAID 1. The trustworthiness of the data is automatically increased with each medium on which it is duplicated. However, it is important to realize that storage capacity does not rise as the number of hard drives increases, but is always restricted by the capacity of the smallest constrained component.

What are the benefits and drawbacks of a RAID 1 configuration?
RAID 1 is distinguished by its simplicity when compared to other storage arrays. All mounted drives have the same data, i.e. the system's whole data supply at any one time. With the right hardware, each hard disk could theoretically be operated and used in its own computer. There's also the benefit of not having to worry about a single component failing: The RAID-1 system can continue to function normally, and the malfunctioning hard disk can be replaced whenever it is convenient.

A RAID should not be viewed as a substitute for or replacement for a backup solution! There is no method to retrieve data lost in a RAID 1 array, for example, because it was unintentionally erased or because a data block was destroyed.

If the controller or management software supports simultaneous access to more than one storage medium, RAID 1 can provide enhanced read speed and additional disk protection. This is made possible in the first situation by parallel access to separate sectors, and in the second case by data alignment.

Because each hard drive in the array must have the same data status, a significant amount of potential store space is lost. RAID-1 storage, on the other hand, is at least twice as expensive as individual data carriers with the same storage capacity (when two hard drives are joined). When compared to other RAID levels that provide redundancy utilizing parity, RAID 1's high cost factor is also a drawback.

Advantages Disadvantages
Redundancy in full The array's storage capacity is limited to the capacity of the smallest hard drive.
A proper controller or software can optionally boost data security and speed. Factor of high cost

Where does RAID 1 come into play?

When high availability of stored data is necessary, combining hard disks in a RAID 1 is always useful. These redundant arrays, however, are not suited for backing up huge amounts of data because their storage is relatively expensive. Server systems of many types (including operating systems) are suitable application situations, such as installations for file servers or web servers.

RAID 1 is also frequently used in conjunction with other RAID levels to construct even more powerful storage solutions. The RAID 10 (also known as RAID 1+0) combination is very popular, as it provides both RAID 1 protection and highly optimized read and write performance.

After RAID 1, regular backups are also required in hardware installations. 

What are the other RAID levels that matter?
RAID 1 provides data redundancy according to the traditional RAID specification. Other levels store data redundantly as well, but they do so in a different way than RAID 1. RAID 5 and RAID 6, for example, do not replicate the user data and instead rely on parity information to maintain redundant storage. A RAID 0 system, on the other hand, operates fully without redundancy, making it a "redundant" array of separate disks in the strictest sense. Our huge RAID level comparison provides a thorough examination of the various RAID configurations.

Logical data loss on RAID

  • Firmware Update Failed
  • Configuration of the RAID controller deleted
  • Deleting folders and files
  • Deleting share folders
  • RAID formatting
  • RAID accidentally disbanded
  • Loss of array data
  • Loss of the order of the hard disks
  • Encrypted volume damaged
  • Accidental deletion of the array volume
  • Virus attack, Trojan horse

Symptoms of RAID failure

  • Shares not accessible
  • In degraded mode Read only
  • Invalid RAID volume
  • Critical state of the array / composite
  • Network share disappeared
  • RAID offline
  • RAID critical
  • RAID is reported as degraded
  • Storage - compound offline
  • Symptoms of RAID failure
  • volume crashed
  • Volume crashed / lost

Mechanical damage to RAID

  • Bad Blocks or defective sectors
  • Damaged read-write heads
  • Defective RAID controller
  • Defect of the server mainboard (integrated RAID controller)
  • Defective PCB (Printed Circuit Board) Hard disk drive circuit board
  • Data loss caused by fire
  • Data loss caused by water
  • Hard drives Firmware error
  • Falling, crash and impact damage
  • Hard disk damages due to natural disasters
  • Head-Crash with hard disk in RAID
  • HDD failure due to wear and tear
  • HDD failure due to overheating
  • Motor damage to hard disk
  • Surface damage of hard disk in RAID
  • Problems with the servomechanism
  • Rebuild for mechanically damaged hard disks
  • Damaged surface within the service area

Symptoms of RAID failure

  • Device I/O error
  • Plate failed
  • No drive
  • Failed hard disk
  • Shares not accessible
  • In degraded read only mode
  • Invalid RAID volume
  • Critical state of the array / composite
  • LED on RAID hard disk red
  • Multiple hard disk failure
  • Network share disappeared 
  • RAID critical
  • RAID offline
  • RAID server beeps, beeps
  • RAID is reported as degraded
  • Server does not start or boot
  • Storage - compound offline
  • Volume crashed / lost
  • volume crashed