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Disk Controller - PowerPoint PPT Presentation


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Disk Characteristics. Rotational Delay. To disk subsystem . Disk Controller. Disk Block Block Size. Seek time. Capacity Rotational Speed (RPM) Seek Time Interface (SCSI, ATA, Serial ATA, Serial Attached SCSI, Fiber Channel). Disk Block and Record Storage. Disk Block

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Presentation Transcript
slide1

Disk Characteristics

Rotational Delay

To disk subsystem

Disk Controller

Disk Block

Block Size

Seek time

Capacity

Rotational Speed (RPM)

Seek Time

Interface (SCSI, ATA, Serial ATA, Serial Attached SCSI, Fiber Channel)

slide2

Disk Block and Record Storage

Disk Block

Record size (Fixed / Variable)

Spanned vs. Unspanned

Blocking Factor

b6

b7

b8

b9

b10

b11

b12

b13

Disk Block

C101^Smith^Joe^Hanover^NJC102^Green^Ed^Lodi^NY 

Record 1

Record 2

Record separator

Field separator

slide3

Spanned vs. Unspanned Record Organization

Unspanned Record Organization

R1

R2

R3

R4

R5

R6

b6

b7

b8

b9

Spanned Record Organization

R1

R2

R3

R4

R5

R6

b6

b7

b8

b9

slide4

Block

101

102

103

104

FNAME LNAME EMPID DNO SALARY

JOHN SMITH 123456789 5 30000

FRANKLIN WONG 333445555 5 40000

JOYCE ENGLISH 453453453 5 25000

RAMESH NARAYAN 666884444 5 38000

JAMES BORG 888665555 1 55000

JENNIFER WALLACE 987654321 4 43000

AHMAD JABBAR 987987987 4 25000

ALICIA ZELAYA 999887777 4 25000

Primary Index

I-Field Block

123456789 101

453453453 102

888665555 103

987987987 104

slide5

Block

101

102

103

104

FNAME LNAME EMPID DNO SALARY

JOHN SMITH 123456789 5 30000

FRANKLIN WONG 333445555 5 40000

JOYCE ENGLISH 453453453 5 25000

RAMESH NARAYAN 666884444 5 38000

JAMES BORG 888665555 1 55000

JENNIFER WALLACE 987654321 4 43000

AHMAD JABBAR 987987987 4 25000

ALICIA ZELAYA 999887777 4 25000

Secondary Index

Record Pointer

I-Field Block Record Offset

BORG 103 1

ENGLISH 102 1

JABBAR 104 1

NARAYAN 102 2

SMITH 101 1

WALLACE 103 2

WONG 101 2

ZELAYA 104 2

slide6

Block

101

102

103

104

FNAME LNAME EMPID DNO SALARY

JAMES BORG 888665555 1 55000

JENNIFER WALLACE 987654321 4 43000

AHMAD JABBAR 987987987 4 25000

ALICIA ZELAYA 999887777 4 25000

JOHN SMITH 123456789 5 30000

FRANKLIN WONG 333445555 5 40000

JOYCE ENGLISH 453453453 5 25000

RAMESH NARAYAN 666884444 5 38000

Secondary Index

Clustering Index

Record Pointer

I-Field Block Record Offset

BORG 101 1

ENGLISH 104 1

JABBAR 102 1

NARAYAN 104 2

SMITH 103 1

WALLACE 101 2

WONG 103 2

ZELAYA 102 2

I-Field Block

1 101

4 101

5 103

slide7

Block

101

102

103

104

FNAME LNAME EMPID DNO SALARY

JAMES BORG 888665555 1 55000

JENNIFER WALLACE 987654321 4 43000

AHMAD JABBAR 987987987 4 25000

ALICIA ZELAYA 999887777 4 25000

JOHN SMITH 123456789 5 30000

FRANKLIN WONG 333445555 5 40000

JOYCE ENGLISH 453453453 5 25000

RAMESH NARAYAN 666884444 5 38000

B Tree Index

NARAYAN

ENGLISH

WALLACE

BORG ENGLISH

101 104

JABBAR NARAYAN

102 104

SMITH WALLACE

103 101

WONG ZELAYA

103 102

slide8

Block

101

102

103

104

FNAME LNAME EMPID DNO SALARY

JAMES BORG 888665555 1 55000

JENNIFER WALLACE 987654321 4 43000

AHMAD JABBAR 987987987 4 25000

ALICIA ZELAYA 999887777 4 25000

JOHN SMITH 123456789 5 30000

FRANKLIN WONG 333445555 5 40000

JOYCE ENGLISH 453453453 5 25000

RAMESH NARAYAN 666884444 5 38000

B+ Tree Index

NARAYAN

ENGLISH

WALLACE

BORG ENGLISH

101 104

JABBAR NARAYAN

102 104

SMITH WALLACE

103 101

WONG ZELAYA

103 102

slide9

Block

101

102

103

104

FNAME LNAME EMPID DNO SALARY

JAMES BORG 888665555 1 55000

JENNIFER WALLACE 987654321 4 43000

AHMAD JABBAR 987987987 4 25000

ALICIA ZELAYA 999887777 4 25000

JOHN SMITH 123456789 5 30000

FRANKLIN WONG 333445555 5 40000

JOYCE ENGLISH 453453453 5 25000

RAMESH NARAYAN 666884444 5 38000

B* Tree Index

NARAYAN

104

ENGLISH

104

WALLACE

101

BORG ENGLISH

101 104

JABBAR NARAYAN

102 104

SMITH WALLACE

103 101

WONG ZELAYA

103 102

some definitions
Some Definitions
  • Block Size: Minimum Fixed sized unit that can be read or written on disk (in Bytes)
  • Record Size: Size of a data record for a particular table. Add together field/column sizes (in Bytes)
  • Blocking Factor: The number of data records than can fit in a data block (in Records per Block)
  • Index Entry Size: The size of an index entry calculated as either (in Bytes):
    • (Primary, Clustering) The size of the indexed column + size of the block pointer
    • (Secondary) The size of the indexed column + size of the block pointer + the size of the record offset
  • Fan Out: The number of index entries that can fit in a Block (in Index entries per block)
  • Number of first level index entries:
slide11

Example: Primary Index

Block Size: 512 Bytes Record Size: 35 Bytes nRecords: 6200

bFactor:  512 / 35  = 14 rec/block nBlocks:  6200 / 14  = 443 blocks

Index Entry Size: 19 Bytes Fan Out:  512 / 19  = 26 index entry/block

First Index Level:  443 / 26  = 17.03846  = 18 Blocks

Second Index Level:  18 / 26  = 1 Block

Total Number of Levels: 2 Levels (check with Log26 443)

Total Size of Primary Index: (18 + 1) = 19 Blocks

I1 I27 I53 … I418

2nd Level

Index

1st Level

I1 I2 I3 I4… I26

I27 … I52

I53 … I78

I418 … I443

IB1

IB2

IB3

IB17

R1 … R14

R15 … R28

…R6200

Data

Block 1

Block 2

B3

B4

B26

B27

B52

B53

B78

B79

B443

slide12

Example: Secondary Index

Block Size: 512 Bytes Record Size: 35 Bytes nRecords: 6200

bFactor:  512 / 35  = 14 rec/block nBlocks:  6200 / 14  = 443 blocks

Index Entry Size: 20 Bytes Fan Out:  512 / 20  = 25 index entry/block

First Index Level:  6200 / 25  = 248 Blocks

Second Index Level:  248 / 25  = 10 Blocks

Third Index Level:  10 / 25  = 1 Block Total Size: 259 Blocks

Total Number of Levels: 3 Levels (check with Log25 6200)

I1 I626 …. I5626

3nd Level

IB259

2nd Level

I626 … I1250

I5626 … I6176

I1 I26 I51 … I625

Index

IB249

IB250

IB258

I1 I2 I3 I4… I25

I26 … I50

I51 … I75

I6176 … I6200

1st Level

IB3

IB1

IB2

IB248

R1 … R14

R15 … R28

…R6200

Data

Block 1

Block 2

B3

B4

B26

B27

B52

B53

B78

B79

B443

slide13

Example: Secondary Index – Close Up View

I1 I626 I1251 I1876 I2501 I3126 I3751 I4376 I5001 I5626 I6251

IB259

I626 I651 I676 I701 I726 …. I1176 I1201 I1226

I1 I26 I51 I76 …. I526 I551 I576 I601

IB249

IB250

I1 I2 I3 I4 I5 I6 I7 I8 I9 I10 I11 I12 I13 I14 I15 I16 I17 I18 I19 I20 I21 I22 I23 I24 I25

I26 I27 I28 I29 I30 I31 I32 I33 I34 …

IB1

IB2

R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14

R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R25 R26 R27 R28

Data Block 1

Data Block 2

slide14

Ordered File

Block

b1

b2

b3

b4

FNAME LNAME SSN DNO SALARY

JAMES BORG 888665555 1 55000

JOYCE ENGLISH 453453453 5 25000

AHMAD JABBAR 987987987 4 25000

RAMESH NARAYAN 666884444 5 38000

JOHN SMITH 123456789 5 30000

JENNIFER WALLACE 987654321 4 43000

FRANKLIN WONG 333445555 5 40000

ALICIA ZELAYA 999887777 4 25000

slide15

Unordered File

Block

b1

b2

b3

b4

FNAME LNAME SSN DNO SALARY

RAMESH NARAYAN 666884444 5 38000

ALICIA ZELAYA 999887777 4 25000

JAMES BORG 888665555 1 55000

JOHN SMITH 123456789 5 30000

JENNIFER WALLACE 987654321 4 43000

FRANKLIN WONG 333445555 5 40000

AHMAD JABBAR 987987987 4 25000

JOYCE ENGLISH 453453453 5 25000

slide16

Indexed File

Block

b1

b2

b3

b4

FNAME LNAME SSN DNO SALARY

RAMESH NARAYAN 666884444 5 38000

ALICIA ZELAYA 999887777 4 25000

JAMES BORG 888665555 1 55000

JOHN SMITH 123456789 5 30000

JENNIFER WALLACE 987654321 4 43000

FRANKLIN WONG 333445555 5 40000

AHMAD JABBAR 987987987 4 25000

JOYCE ENGLISH 453453453 5 25000

Index

Record Pointer

I-Value Block

BORG b2

ENGLISH b4

JABBAR b4

NARAYAN b1

SMITH b2

WALLACE b3

WONG b3

ZELAYA b1