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Slide 1
Redundant Array of Inexpensive Disks
Slide 2
CONTENTS Storage devices. Optical drives. Floppy disk. Hard
disk. Components of Hard disks. RAID technology. Levels in RAID
technology. Summary.
Slide 3
Storage devices Some of the storage devices are as follows:
Optical drives such as floppy disks,CD/DVD Rom Hard disks.
Slide 4
Floppy disk drives. FLOPPY DISK
Slide 5
CD/DVD drives
Slide 6
Geometry of hard disk Hard disk is an organization of data on
the platters. It shows where the data will be stored in each
platters. They are specified by numerical values such as: Heads.
Cylinders. Sectors per track. Write precompensation. Landing
Zone.
Slide 7
Components of Hard disk. o Platters and Media o Read/Write
Heads o Head Sliders, Arms and Actuator o Spindle Motor o
Connectors and Jumpers o Logic Board o Integrated Cache
Slide 8
Sectors per track.
Slide 9
Types of Hard disk SCSI Hard disk. SATA Hard disk.
IDE(ATA/PATA).
Slide 10
IDE (Integrated Drive Electronics) IDE is older type of Hard
disk. It is also called ATA/PATA hard disk. Some of the IDE hard
disk are as follows: ATA-1 ATAPI (ATA Packet Interface) ATA-2
ATA-3: ATA/ATAPI-4 ATA/ATAPI-5: Enhanced IDE (EIDE Fast ATA Ultra
ATA
Slide 11
SATA (Serial ATA Hard disk) SATA is latest technology that is
replaced by PATA/ATA hard disk. SATA has several advantages over
PATA they are as follows: Superior cabling and connectors. Higher
bandwidth. Greater reliability.
Slide 12
SCSI (Small Computers System Interface) These hard disks are
used in workstations and servers because of following advantages:
Improved performance over IDE and SATA in multitasking and
multiuser environment. Ability to dairy chain many drivers on
computer.
Slide 13
RAID (Redundant Array of Inexpensive Disk) RAID is the method
in which information is spread across several hard disk and
maximize the ability to recover information in case of hard disk
crash.
Slide 14
Some Information about RAID technology i. Mirroring refers to
copying of data to multiple hard disks. ii. Striping refers to
splitting of data across multiple hard disks. iii. Error correction
refers to detecting hard disk failures and recovering from the
failures. Error detection is done by parity checking.
Slide 15
Different levels of RAID are as follows: RAID 0 RAID 1 RAID 3
RAID 4 RAID 5 RAID 6 RAID 10 RAID 53
Slide 16
RAID 0 level RAID 0 level specifies data stripping. It means
that data will split up into several smaller parts without any
parity. It requires minimum 2 number of hard disks to operate. RAID
0 level provides good performance over single disk storage.
Slide 17
RAID 1 level Specifies data Mirroring(same copy of data in all
hard disks) but without any parity. This means data is copied to
multiple disk but there is no error correction of RAID1 level like
RAID 0 level also requires at least two hard disk drivers.
Slide 18
RAID 2 level ( Stripping with parity.) RAID 2 level suggests
data is split across multiple hard disk with parity bit is stored
in the same hard disk. If any data is lost then we can recover
disk. If any data is lost then we can recover the whole data with
the help of parity bit. Minimum 2 HDD is required
Slide 19
RAID3 level RAID 3 level specifies data stripping with
dedicated parity disk. This means RAID 3 level generates parity and
dedicated one of its hard disk drive for storing the parity
information. Minimum 3 HDD is required for building RAID3
level.
Slide 20
RAID 3: XOR Exit Hamming Code, Enter XOR (eXclusive OR) XOR in
Action: 0101 2 XOR 0011 2 = 0110 2 If ???? 2 XOR 1100 2 = 0110 2,
Then 1100 2 XOR 0110 2 = ???? 2 = 1010 2 Thus we can use XOR
results to recover lost data XOR Logic Table A XOR BR esult 000 011
101 110
Slide 21
RAID 3: Pros and Cons Advantages: High Read/Write Transfer
Rates Disk failures dont slow the system Low Ratio of Data Disks to
Parity Disks Disadvantages: Transaction rate slowed by Parity Disk
Complex Controller Design Software Implementation Resource
Intensive
Slide 22
RAID 3: Uses Video Production High-end Video and Image Editing
Other uses that require high throughput of data
Slide 23
RAID 4 level RAID 4 level is similar to RAID 3 except with a
difference. The difference is that : In RAID 3 we stripes data one
byte at time. Whereas RAID 4 strips data in blocks.
Slide 24
RAID 4: Uses Advantages: Very high read rates Multiple files
read at once Uses: Web Servers, and other high read, low write
situations Disadvantages: Very slow write rates Even small writes
fill up parity write queue Inefficient data recovery Even more
Complex Controller Design than RAID 3 *Has most of the other
Advantages and Disadvantages of RAID 3
Slide 25
RAID 5 level RAID 5 took all the advantages from RAID 0-RAID 4
and build up this technology. The advantages are as follows: RAID
0-Stripping. RAID 1-Mirroring. RAID 2-Stripping bit level parity.
RAID 3-Stripping with dedicated parity. RAID 4-Block level parity.
Therefore, RAID 5 level has got highest popularity as it uses all
the level and it is used widely.
Slide 26
RAID 5 Highest Read data transaction rate Medium Write data
transaction rate Most complex controller design Used For Server
Applications.
Slide 27
RAID 10 Characterized by: - each drive duplicated - high
implementation cost
Slide 28
RAID 10 Uses multiple (mirrored) RAID 1 in a single array Data
striped across all mirrored sets Very high fault tolerance High
performance rate
Slide 29
How are the HDD are designed in RAID technologies
Slide 30
Advantages of RAID The foremost advantage of using a RAID drive
is that it increases the performance and reliability of the system.
The RAID drive is a credible example that could be used in a
server. The RAID increases the parity check and thus it regularly
checks for any possibility of a system crash. Disk stripping is
also a hot topic when we discuss about the RAID drives. The
performance is much highlighting and increases a lot when the disk
stripping is done. The mirroring is the complete duplication of the
data. Or in the other sense the mirroring is the 100% duplication
of the data on two drives.
Slide 31
Disadvantages of Raid A major disadvantage regarding the RAID
drive is that there needs to be written the drivers for a Network
Operating System (NOS). Hence the major fact and also the most
important usage of the RAID system is that it is essentially
designed and extensively used in a server. Another disadvantage
regarding the RAID is that it is very much difficult for an
administrator to configure the RAID system. The ability to
dynamically enlarge the RAID server is also complex process;
especially for those administrators who are the IS managers and
also the LAN administrators.
Slide 32
Summary RAID level Mirroring Striping Parity Min. drives Key
features 0 No Block No 2 Fastest, but lacks data protection. 1 Yes
No 32No 2 Requires double capacity but fastest protected solution.
3 No Byte Dedicated 3 Distributes each block across disks. 4 No
Block Dedicated 3 Larger blocks improve performance. Dedicated
parity disk is potential bottleneck. 5 No Block Distributed 3
Eliminates parity bottleneck.
Slide 33
Thank you ANJAN KUAMR.B. -Guided by Mr. Pintunath.