17-1-2011 ,

/ : : (sectors): : interblock gaps (cluster) :

(Sector) (= block=page) /

(platter) (cylinder)

(track)

record : .

(values) (fields) : Byte

File :

bfr= B/R

B= bytes R= bytes

B-(bfr*R) bytes (spanned)

bfr # r

r : b : r b= r/bfr

(unspanned)

r=20.000 . :

(30 byte) (9 byte) (40 byte) (9 byte) _(8 byte) (1 byte) _(4 byte) _ (4 byte) ( 4 byte) _(3 byte)

1 -

B=512 byte =20 = 400 15

1 -

; ; ; ; R byte. bfr b,

1 - ; 20 * 512 Byte = 10kb ; : . 400

1 - 1 15 * = 30 . :

30 * 10=300 kb

1 = 400 .

300 * 400=120Mb

1 - R byte (30byte +9+40+9+8+1+4+4+4+3+1 ) R=113 bfr b,

bfr= B/R = 512/113 = 4

b=r/bfr=20000/4=5000

-

:(b/2)block - ( ) - ( ) : log2(b) block ( )

(index) () (indexing field)

block

: ( ) :

.

2 -

r = 30000 B=1024 byte R=100 byte

; 1.

2. 3.

bfr=(/R)=10 b=(r/bfr)=3000

log2b= log23000=12

2

V=9byte block P=6 byte

;

Ri=9+6=15byte bfri=1024/15=68

bfri=(/Ri)

ri

bi= (ri/bfri)= (3000/68) =45 block (log2bi) = (log245) =6 block

ri=# =3000 ( )

-

: +

3

r = 30000 B=1024 byte R=100 byte

;

bfr=(/R)=10 b= (r/bfr) =3000

b/2=3000/2=1500 .

3

- V=9byte block P=6 byte

Ri=9+6=15byte bfri= (/Ri)=1024/15=68 . O ri 30000. bi= (ri/bfri)= (30000/68)=442 block (log2bi)= (log2442)=9 block 10 block

: bfri =fo ( (fan-out))

fo>2 logfobi213 =14

!!!