2. RAID
1) RAID USED TO INCREASE DATA STORAGE PERFORMANCE.
2) RAID stands for “Redundant array of independent disk”.
3) Used in laptop, servers, data centers, cloud computing etc.
4) Single disk = storage in laptop.
5) Multiple disk= servers , data centers, cloud computing.
6) Raid saves data in multiple disk. It is a set of multiple hard disk which are in network.
7) Caches =increase performance in laptop.
8) Additional disk = also increase performance.
9) Multiple i/o request =handled at the same time.
10) Single i/o request =also handle at the same time
3. Benefit
Prevent data loss due to disk failure.
Used in servers.
To prevent faile of operating system Raid technology is beneficial.
Raid technology can be implemented in hardware or software.
4. RAID TECHNOLOGY
7 layers:
RAID 0, used in servers now a days
RAID 1,
RAID 2, Much complicated and outdated.
RAID 3,
RAID 4,
RAID 5, used in servers now a days.
RAID 6.
5. Characteristics of 7
layers
1. A set of physical disk drives
2. Redundant disk capacity is used to store parity information.
3. Parity information is used to recovering the data in case of
disk failure.
4. O.S views these separate disk as a single logical disk.
6. About parity
Parity check:
A parity check is a process in which
accurate data transmition between
nodes during communication is
checked .
7. RAID level 0
Required 2 disk(minimum).
No redundancy.
Stripping= Division of data and save on different disks.
No parity check .
If one disk fail all data is lost.
RAID 0 does not support recover data.
ADVANTAGES DISADVANTAGES
Fast processing . 1) Not provide fault tolerance.
Data stripping. 2) Not used in critical environment.
Throughput increase. 3) No backup facility.
Implementation is easy.
No overhead of parity calculation.
8. RAID LEVEL 1
No data stripping.
Mirroring = copies of data onto two disk drives simultaneously.
Minimum two hard drives.
Automatic duplication.
Read data on any disk.
No parity check.
Store data on every disk.
Raid 1 is used in O.S.
Write request mean both disk updated.
9. RAID 1
ADVANTAGES DISADVANTAGES
1) Fault tolerance. 1) Storage cost is increase.
2) Provide data redundancy.)
3) RAID 1 Is Used to store system
software (o.s,compilers,drivers etc.) (due to duplication of data)
4) If one disk fails, the other automatically
takes over.
10. RAID LEVEL 2
All disks are participate in the execution of every I/o request.
Data stripping .
Check parity.
Costly to implement.
Individually disk are synchronized.
11. RAID LEVEL 3
Required minimum 3 disks.
Byte level stripping.
Dedicated parity.
Two types of parity
Dedicated parity Distributed parity
Separate and same storage If one fails other disk recover
Backup.Sepparate disk is used data.
to recover data
12. RAID LEVEL 4
Required minimum 4 disks.
Same as RAID 3.
Block level stripping
Two types of level
Byte level Block level
Divide byte and save data. divide block and save data.
13. RAID 5
Mostly used RAID 5.
RAID 5 technique is used in data centers, large computing
centers etc.
RAID 5 required minimum 3 disks.
1 hard disk is used to store parity bit, when data get
corrupted.
Parity checking is involved.
Raid 5 include stripping and mirroring.
RAID 5 used byte level stripping with distributed parity.
14. HOW RAID 5 DO ERROR
CHECKING
If one disk corrupt or error occurred
then specific data of this disk is
copied to another disk
15. RAID LEVEL 6
Same as RAID 5.
Extra parity bit storage than RAID 5
Required 6 minimum disk.
Byte level stripping with double distributed parity.
If one storage parity is failed then other parity will take place.
Two parity backup are available in RAID LEVEL 6.
16. RAID 10 (1,0)
Combination of RAID 1 and RAID 0
Combination of disk mirroring and disk stripping to protect data.
Provide fault tolerance.
I/O operation faster due to stripping .
Provide data redundancy and performance.
Required minimum of 4 disks.
