RAID Levels & Types | RAID 0, RAID 1, RAID 3, RAID 5, RAID 7, RAID 10 Page 1 of 3
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RAID Levels and Types
RAID, an acronym of Redundant Array of Independent (Inexpensive) Disks
talk of the day. These are an array of disk to give more power, performance, fault
tolerance and accessibility to the data, as a single storage system. It's not mere
combination of disks but all the disks are combined providing standard MTBF (mean
time before failure) reliability scheme; otherwise chances are performance
affected drastically if disks are not combined as a single storage unit.
RAID Levels
All the RAID types and models are commonly classified as RAID levels, since RAID
represented by a higher number is regarded to be superior, more efficient,
performance array than the low numbered RAID.
Hence, high security feature of RAID also depends on the RAID level you are using.
RAID arrays, not only, provide the users with maximum security and reliability but
also make sure that if a disk fails no data is lost. The in-depth knowledge about RAID
levels would help you through buying of RAID servers.
Let's briefly discuss here the main RAID levels and classes:
RAID 0 - Striping:
It is the Stripped Disk Array with no fault tolerance and it requires at least 2 drives
to be implemented. Due to no redundancy feature, RAID 0 is considered to be the
lowest ranked RAID level. Striped data mapping technique is implemented for high
performance at low cost. The I/O performance is also improved as it is loaded across
many channels. Regeneration, Rebuilding and functional redundancy are some salient
features of RAID 0.
RAID 1 - Mirroring:
It is the Mirroring (Shadowing) Array meant to provide high performance. RAID 1
controller is able to perform 2 separate parallel reads or writes per mirrored
also requires at least 2 drives to implement a non-redundant disk array. High level of
availability, access and reliability can be achieved by entry-level RAID 1 array. With fu
redundancy feature available, need of readability is almost negligible. Controller
configurations and storage subsystem design is the easiest and simplest amongst all
RAID levels.
RAID 0+1:
It is the RAID array providing high data transference performance with at least 4 disks
needed to implement the RAID 0+1 level. It's a unique combination of stripping and
mirroring with all the best features of RAID 0 and RAID 1 included such as fast data
access and fault tolerance at single drive level. The multiple stripe segments have
added high I/O rates to the RAID performance and it is the best solution for maximum
reliability.
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RAID Levels & Types | RAID 0, RAID 1, RAID 3, RAID 5, RAID 7, RAID 10 Page 2 of 3
RAID 2 (ECC):
It is the combination of Inherently Parallel Mapping and Protection RAID
It's also known as ECC RAID because each data word bit is written to data disk which i
verified for correct data or correct disk error when the RAID disk is read. Due to specia
disk features required, RAID 2 is not very popular among the corporate data
masses, despite the extremely high data transference rates.
RAID 3:
RAID 3 works on the Parallel Transfer with Parity technique. The least number of
disks required to implement the RAID array is 3 disks. In the RAID 3, data blocks are
striped and written on data drives and then the stripe parity is generated, saved and
afterwards used to verify the disk reads. Read and write data transfer rate is very high
in RAID 3 array and disk failure causes insignificant effects on the overall performance
of the RAID.
RAID 4:
RAID 4 requires a minimum of 3 drives to be implemented. It is composed of
independent disks with shared parity to protect the data. Data transaction rate for
Read is exceptionally high and highly aggregated. Similarly, the low ratio of
disks to data disks indicates high efficiency.
RAID 5:
RAIDS 5 is Independent Distributed parity block of data disks with a minimum
requirement of at least 3 drives to be implemented and N-1 array capacity. It helps in
reducing the write inherence found in RAID 4. RAID 5 array offers highest data
transaction Read rate, medium data transaction Write rate and good cumulative
transfer rate.
RAID 6:
RAIDS 6 is Independent Data Disk array with Independent Distributed parity
is known to be an extension of RAID level 5 with extra fault tolerance and distributed
parity scheme added. RAID 6 is the best available RAID array for mission critical
applications and data storage needs, though the controller design is very complex and
overheads are extremely high.
RAID 7:
RAID 7 is the Optimized Asynchrony array for high I/O and data transfer
is considered to be the most manageable RAID controller available. The overall write
performance is also known to be 50% to 90% better and improved than the
spindle array levels with no extra data transference required for parity handling. RAID
7 is registered as a standard trademark of Storage Computer Corporation.
RAID 10:
RAID 10 is classified as the futuristic RAID controller with extremely high Reliability
and performance embedded in a single RAID controller. The minimum requirement to
form a RAID level 10 controller is 4 data disks. The implementation of RAID 10 is
based on a striped array of RAID 1 array segments, with almost the same fault
tolerance level as RAID 1. RAID 10 controllers and arrays are suitable for
uncompromising availability and extremely high throughput required systems and
environment.
With all the significant RAID levels discussed here briefly, another important point to
add is that whichever level of RAID is used regular and consistent data backup
maintenance using tape storage is must as the regular tape storage is best media to
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recover from lost data scene.
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