Raid Levels Technology

Presented By : Ishwor Panta
Roll No. : 13
Presentation on RAID

RAID
 Redundant Array of Independent Disks
 Example of storage virtualization
 Combines multiple disk drives into logical unit
 Provides data integrity, fault tolerance, throughput
compared to single driver
 Typically used in server computer and advanced
personal computers

RAID
 Basic Idea is to connect multiple disks to provide :
 Large Storage Capacity
 Faster Access to reading data
 Redundant Data
 Increase Performance

Working of RAID
 Combine multiple independent inexpensive disk
and group them together
 OS sees the combined disk as a single logical disk
 RAID Controller Card is used to handle all I/O to
disks and locate the stored data
 RAID Controller is a hardware device or software
program used to manage array of Storage devices.

RAID TERMINOLOGY
 Mirroring :
 Copying of data to multiple hard disks
 Striping:
 Splitting of data across multiple hard disks
 Error Correction:
 Detecting hard disk failure and recovering from
the failure, done with parity checking

RAID LEVELS
 RAID 0 (Striping)
 RAID 1 (Mirroring)
 RAID 2 (Redundancy through Hamming)
 RAID 3 (Bit interleaved parity)
 RAID 4 (Block interleaved parity)
 RAID 5 (Striping with parity)
 RAID 6 (extended of RAID 5)

RAID 0
 Striping
 Offer superior I/O
 Performance can be enhanced
 by using multiple controller
 Requires minimum of 2 disks
 No fault tolerance

RAID 1
 Mirroring
 Controller uses either the
 data drive or the mirror drive
 for data recovery
 Two minimum disk required
 Storage capacity is half of
 total disk capacity

RAID 2
 Redundancy through
 hamming code
 Stripe data at bit level
 rather than block
 Minimum 3 disk are required
 Data transfer rate is very high
 Single bit error can be detected and corrected

RAID 3
 Bit interleaved parity
 Files are broken into
 “byte-sized pieces”
 Written in parallel in two
 or more drives
 Additional drive stores parity information
 High throughput for large data transfer
 Minimum of 3 disk are required

RAID 4
 Block interleaved parity
 High read rate but slow
 write rate
 Each file is split into blocks
 of certain size
 Service multiple read request simultaneously
 Fault tolerance is very high
 Three minimum disk are required

RAID 5
 Striping with parity
 Most secure RAID
 Parity information is
 spread across all drives
 Read data transactions are
 very fast
 Disk failure may have an effect on throughput
 Complex technology

RAID 6
 Extension of RAID 5 level
 with additional fault
 tolerance (independent
 parity scheme)
 Data is striped as like in
 RAID 5 on block level
 Can sustain from multiple drive failures
 Poor write speed and complex system

RAID 1+0
 Uses multiple RAID1
 in single array
 Data striped across
 all mirrored sets
 High fault tolerance
 High performance rate
 High implementation cost

References
 http://www.acnc.com/raid.html
 https://en.wikipedia.org/wiki/Standard_RAID_levels

Raid Levels Technology

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