F?s??? ??????s? ??se?? ?ed?

1
11

• F?s??? ??????s? ??se?? ?ed?µ????

• ??p?? ????af??
• ??p?? Se??d??
• ?µad?p???s? ????af??
• ??a?e???s? ????? ??s???
• ??a?e???s? ?p?µ???t???? ???µ??

2
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??ep???e?e? ?e?t???????? S?st?µ?t??

• Se s?st?µata t?? 32 bit, t? µe?a??te?? µ??e???
  a??e??? e??a? 4 Gb
• O t??p?? ??????s?? t?? a??e??? e?a?t?ta? ap? t?
  ?e?t??????? S?st?µa
• ???sa?µ??? t?? S??? ?? p??? t?? ?d?a?te??t?te?
  t?? ???e ?e?t??????? S?st?µa

3
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?µ?µata t?? S??? s?et??? µe t? f?s??? ??????s?
t?? ded?µ????
4
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?µ?µata t?? S??? s?et??? µe t? f?s??? ??????s?
t?? ded?µ????

• ? ??a?e???st?? ????? ??s??? e??a? t? ?pe?????
  ????sµ??? ??a t?? a?????s? ?a? t?? ap????e?s?
  se??d?? st? d?s??.
• ? ??a?e???st?? ???µ?? ?p?µ???s?? e??a? t?
  ?pe????? ????sµ??? ??a t?? ?at?tµ?s? t?? ????a?
  µ??µ?? se ?at?????a tµ?µata ?ste ta pe??e??µe?a
  t?? se??d?? ?a ap????e???ta? p??s????? ap? t?
  d?s??.
• O ??a?e???st?? ???e??? e??a? ??a s?????
  p????aµµ?-t?? p?? ???p????? d??f??e? d?µ??
  a??e??? ?a? ep?s?? e??a? ?pe?????? ??a t??
  ta?t?p???s? t?? e???af??.

5
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????te?t????? e??? ?p?????st???? s?st?µat??

• ? ep????????a µeta?? t?? ????a? µ??µ?? ?a? t??
  ß?ad?te??? de?te?e???s?? µ??µ?? ???eta?
• sta µe???a s?st?µata µe t? ?a???? (channel),
• sta µ???? s?st?µata µe t? d?a??? (bus) ded?µ????.
• S??p?? e??a? ? e??µ????s? t?? ???µ?? µetaf????
  ded?µ????.

6
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????te?t????? e??? ?p?????st???? s?st?µat??

• ?? ?a???? ??e? d??? t?? µ??µ?, e?? ? ßas??? t??
  ?e?t?????a e??a? ? µetat??p? t?? ???e?? t??
  ????a? µ??µ?? se bytes ?a? t? a?t?st??f?.
• ?p?????? d?? e?d?? ?a????a
• ?p??e?t??? ?a???? p?? e?te?e? p????? t? p????aµµa
  p?? af??? µ?a s?s?e?? p??? ?a a???se? ?a e?te?e?
  t? p????aµµa µ?a? ?????.
• ????p?e?t??? ?a???? p?? e?te?e? ta?t?????a ta
  p?????µµata p????? de?te?e???s?? s?s?e???.

7
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????te?t????? e??? ?p?????st???? s?st?µat??
8
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??p?? e???af??

• ? ??af??? pa??stas? t?? ??????s?? t?? ped??? µ?a?
  e???af?? ???eta? ??aµµ????f?s? (layout).
• ?? e???af?? µ?a? ??t?t?ta? ????? ?d?a µ??f? ?a?
  ?????ta? e???af?? sta?e??? µ?????.
• Sta s?es?a?? µ??t??a ?a??? ?a? sta
  a?t??e?µe-??st?af? s?st?µata p????pt??? e???af??
  µetaß??t?? µ?????.

9
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??e??e?t?µata e???af?? µetaß??t?? µ?????

• ?a p?e??e?t?µata ?? p??? t?? ap????e?s? e??a?
  ?d?a?te?a s?µa?t??? ?ta?
• ?p???e? µe???? ap????s? t?? µ???? t?? e???af??
  ap? t? µ?s? µ???? e???af??,
• ta a??e?a e??a? ????d?,
• e??a? µe???? ? s????t?ta ???s??,
• t? ????? e??a? a???ß?.

10
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
? µetaß??t?t?ta t?? e???af?? ?fe??eta? se

• ped?a µetaß??t?? µ?????
• s?µß???se????, ?p?? ???µata, d?e????se?? ??p

• e???af?? d?af??et???? µ??f??

• epa?a?aµßa??µe?e? ?µ?d?? ped???
• ??. e???af? ?pa?????? µe d?? ? t??a pa?d??

11
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? e???af?? µetaß??t?? µ?????

• ???s? e?d???? d?a????st??
• ?e ???s? e??? µ????? ?ata????? st?? a??? t??
  e???af?? ?p?? ??a ???e ped?? ap????e?eta? ?
  ap?stas? t?? ap? t?? a??? t?? e???af??

12
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??e??e?t?µata ???s?? ?ata????? (2? p??s????s?)

1. ?pa?te? pe??ss?te?? ???? a??? e??a? ???????
   ap?te?esµat???te?? ??at? p??sf??e? ?µes?
   p??sp??as? ???e ped???
2. ?e? apa?te?ta? ? ap????e?s? s???e???µ????
   s?µß???? ??a t?? t?µ? NULL ??p???? ped???, a???
   ap??? ? ap?stas? t?? ep?µe??? ped??? e??a? ?s? µe
   t?? ap?stas? t?? s???e???µ???? ped???.

13
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?e???e?t?µata d?a?e???s?? e???af?? µetaß??t??
µ?????
?? ?????te?? p??ß??µa e??a? ? a???s? t?? µe??????
t?? e???af?? ?at? t?? e??µ???s? e??? ped???,
?p?te a?t? µp??e? ?a p???a??se?

• t?? a????? ta?t?p???s?? t?? pe??e??µ???? t??
  se??da? µe t?? ?at?????? µeta????s? (shifting)
  µe????? e???af??.
• t?? a????? ap????e?s?? t?? s???e???µ???? e???af??
  se ???? se??da ???? a?ep???e?a? ?????.
• a? ? e???af? µeta?????e?, t?te st? ??s? t??
  ap????e?eta? ? ??a d?e????s? ?ste ?a µ? ?a????
  ded?µ??a.

14
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??????s? se??d??

• ???e se??da ??e? ep??efa??da (page header), p??
  pe????e? s?µa?t???? p????f???e?, ?p?? a???µ??
  ap????e?µ???? e???af?? st? se??da, d?e????s?
  ep?µe??? se??da? t?? a??e??? ??p.
• ??a se??da e??a? ??a s????? ??se?? (slots) ??a
  t?? ap????e?s? t?? e???af??. ???e e???af? µp??e?
  ?a ?a?a?t???s?e? ap? t? s?st?µa µe ??a µ??ad???
  ??d??? e???af?? (record identifyer - rid), p??
  ap?te?e?ta? ap? t? ?e???? lt??d???? se??da?,
  a???µ?? ??s??gt (ltpage id, slot numbergt).

15
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????af?? sta?e??? µ????? se se??de?
?p?????? d?? e????e? ??se?? ??a t?? e?t?p?sµ? t??
e???af?? µ?sa st? se??da
1? ??s? ?? e???af?? ap????e??-?ta? st?? p??te?
d?a??s?µe? ??se?? t?? se??da?, ?p?te e??a?
e?????? ? ?p?????sµ?? t?? ap?st?se?? (offsets).
Se pe??-pt?s? d?a??af?? ? te?e?ta?a e???af?
?at??aµß??e? t? ??s? t?? d?a??afe?sa?.
16
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????af?? sta?e??? µ????? se se??de?
?e?????t?µa a? ?p?????? a??s?de? e???af??, ?a?
µ?a e???af? e?t?? t?? s???e???µ???? se??da?
de???e? p??? t? ??s? t?? te?e?ta?a? e???af??,
t?te a?t? de? µp??e? ?a µeta?????e?
2? ??s? ?p????e?eta? st?? ep??e-fa??da ??a?
d?ad???? p??a?a? µe s?µa?e? p?? d??????? a? µ?a
??s? e??a? ?ate???µµ??? ? ???. ?at? t?? a?a??t?s?
e?et????ta? µ??? ?? ??se?? µe a???e?? s?µa?e?,
e?? ? a?t?st???? s?µa?a ?a??stata? ?e?d?? ?at? t?
d?a??af?.
17
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????af?? µetaß??t?? µ????? se se??de?

• ???ß??µata d?µ????????ta? ?a? st?? e?sa???? µ?a?
  e???af?? ?p?? ?a p??pe? ?a ?ata??ße? ??p???
  ?at?????? ?e?? ???? (?????ta? ???p?? ???s? t??
  ?e??? ?????) ?a? st? d?a??af? µ?a? e???af?? ??at?
  ?? ?p????pe? ?a p??pe? ?a µeta???????? ?ste ?
  ?e??? ????? ?a e??a? e??p???µ????.

18
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????af?? µetaß??t?? µ????? se se??de?

• 1? ??s? ??a? ?at?????? ??se?? (directory of
  slots), ? p??a?a? t?p???t?s?? (position table)
  st?? ep?-?efa??da t?? se??da? pe????e? ??a ???e
  e???af? t? ?e???? ltap?stas? e???af??, µ????
  e???af??gt. ?p?p????, ?p???e? ??a? de??t?? p???
  t?? a??? t?? se??da? ap? ?p?? a????e? ? pe?????
  ap????e?s?? t?? e???af??, ?a??? ?a? ??a? de??t??
  p??? t?? a??? t?? e??p???µ???? pe?????? p?? e??a?
  e?e??e?? ?a? d?a??s?µ? ??a ap????e?s? ????
  e???af??.

19
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
????af?? µetaß??t?? µ????? se se??de?

• 2? ??s? ? ?at?????? de? pe????e? ?e???
  ltap?stas? e???af??, µ???? e???af??gt a??? µ???
  t?? ltap?stas? e???af??gt , e?? ? ??de??? µ?????
  (length indicator) t?p??ete?ta? st?? a??? t??
  a?t?st????? e???af??. ?ts?, d?e??????eta? ?
  ?p??ßas? µ?a? e???af?? se pe??pt?s? a?a??t?s??.

20
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?µad?p???s? e???af??

• ?p???t??µe ?t?
• µ???da ap????e?s?? e??a? ? s?????? d?s???,
• ? e???af? e??a? ? e????st? ?????? µ???da
  d?a????s?? p????f???a?,
• ? se??da e??a? t? e????st? f?s??? p?s? ded?µ????
  p?? µetaf??eta? µeta?? t?? d?s??? ?a? t?? ????a?
  µ??µ??.

21
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?µad?p???s? e???af??

• ?a?????ta? ?µad?p???s?? (blocking factor - Bfr)
  e??a? ? a???µ?? t?? e???af?? p?? ?????? se µ?a
  se??da. ?? ?p?te?e? ?t? aµe??t?? µ??e???
  ep??efa??da? t?? se??da? ?a? ?t? ?? e???af??
  e??a? sta?e??? µ?????, t?te ? pa?????ta?
  ?µad?p???s?? ?s??ta? µe
• ?p??
• ? e??a? t? µ??e??? t?? se??da?,
• R e??a? t? µ??e??? t?? e???af??

22
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?µad?p???s? e???af??

• ?? ?? e???af?? e??a? µetaß??t?? µ?????, t?te ?
  µetaß??t? R s?µß????e? t? µ?s? µ???? t??
  e???af??.
• ???se???st???, ? µ?s?? ?e??? ????? ?s??ta? µe t?
  µ?s? t?? µ?s?? e???af?? , ?p?te ? pa?????ta?
  ?µad?p???s?? ???eta?

23
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?µad?p???s? e???af??

• ?? n e??a? t? p????? t?? e???af??, t?te ?
  a???µ?? t?? se??d?? t?? a??e??? e??a?
• ?? ?? ?efa??? e??a? t?p??et?µ??e? st?? a??? t??
  se??da?, t?te ? ?????? µetaf???? t?? se??da?
  ?s??ta? µe

?p?? t e??a? ta??t?ta d?a????s?? t?? ded?µ????
µeta?? d?s??? ?a? µ??µ?? ?a? µet??ta? µe
bytes/ms.

• ?? (a?t? se??da?) ?e????e? µ?a ?t?a?t?? ?, t?te ?
  ?????? µetaf???? ?s??ta? µe
• ?p?? r e??a? ? µ?s?? ?????? pe??st??f??.

24
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??????s? s?????? d?s???

• St? s????? d?s?? apa?te?ta? ??p??a ??????s? µe
  s??p? t? s???????sµ? ?at? t? ?e?t?????a t?? ?a?
  ep?µ???? t? µe??s? t?? ?a??????ta pe??st??f????
  ??????.
• St?? p???? s??a?t??ta? d?? t??p?? ??a t??
  ??????s? e??? d?s???
• ? ?pa??? t?? ?e??? µeta?? t?? se??d??, ?a?
• ? ???s? t?? te?????? t?? pa?eµß????
  (interleaving) p?? ep?t?????e? ?a??te???? ???????
  p??sp??as?? a??? e??a? s?et??? pe??p????.

25
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?e????? pa?eµß????

• ? te????? t?? pa?eµß???? e??a? a?a??a?a epe?d? ?
  e?e??t?? t?? d?s??? apa?te? ??p??? ?????
  epe?e??as?a? t?? ded?µ???? p?? d??eta? ap? t?
  d?s??, p??t?? µp???se? ?a de??e? ???a ded?µ??a.
  ?ts?, a? ? ?????? ep?µe?? se??da t?p??et???ta?
  st?? f?s??? ep?µe?? t?µ?a, t?te ?a ?p?epe ?a
  ???e? µ?a p????? pe??st??f? t?? d?s???, ?ste ?a
  e?t?p?s?e? ? a??? t?? ep?µe??? se??da?.

26
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?e????? pa?eµß????

• ?st? ?t? p??pe? ?a ap????e????? 10 se??de? e???
  a??e??? st??? 10 t?µe?? µ?a? at???t??.
• ?p?s??, a? ?p?te?e? ?t? ? e?e??t?? apa?te?
  d?p??s?? ????? ap? t? ????? p?? apa?te?ta? ??a
  t?? p??sp??as? t?? ep?µe??? t?µ?a.

27
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?e????? pa?eµß????

• St? s???e???µ??? pa??de??µa a????? t?e??
  pe??st??f?? ??a t?? a?????s? ???? t?? t?µ??? t??
  at???t??, e?? ?a ??e?a??ta? d??a pe??st??f?? a?
  de? ???s?µ?p?????ta? ? te????? a?t?.
• ?a te?e?ta?a ?????a ?? ta??t?te? t?? e?e??t??
  ????? ße?t???e? s?µa?t???. ?ts? a?af??eta? ap?
  t??? ?atas?e?ast?? d?s??? ?t? ? ????? pa?eµß????
  e??a? 11, p?? s?µa??e? ?t? ? ?????? se??? t??
  t?µ??? ta?t??eta? µe t? f?s??? se??? t???.

28
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?µat???? ?????? µetaf???? se??da?

• ?ta? ?? d?s??? e??a? f??µa??sµ???? µe t? µ???d?
  t?? ?e???, t?te ?e????µe µ?a ?a???????a µetaß??t?
  p?? ???µ??eta? p?a?µat???? ?????? µetaf????
  se??da? (effective block transfer time) ?a?
  ?s??ta? µe
• ?p?? t' e??a? ? ta??t?ta d?a????s?? ded?µ???? ap?
  f??µa??sµ??? d?s?? st? µ??µ? ?a? µet??ta? ep?s??
  µe bytes/ms.

29
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?a??µet??? ?a? t?µ?? t?? ??? 3380
30
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
?a??t?ta a?????s??

• ? se???a?? a?????s? a??e??? apa?te? ?????
• ? t??a?a a?????s? ???? t?? se??d?? e??? a??e???
  apa?te? ?????

• ?p??
• b e??a? t? µ??e??? t?? a??e??? se se??de?,
• s e??a? ? µ?s?? ?????? a?a??t?s?? se ms,
• r e??a? ? µ?s?? ?????? pe??st??f?? se ms., e??
• ?e??e?ta? aµe??t?? t? µ??e??? t?? ep??efa??da?,
  ?a?
• ?p?t??eta? ?t? ?? e???af?? ????? sta?e?? µ????.

31
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ???a? ???s?µ? ??a s????? se??d?? t?? a??e??? ?a
  ap????e??e? se d?ad?????? at???t??? t?? d?s???,
  ?ste ? se???a?? a???t?s? t??? ?a ???eta?
  ap?te?esµat???.
• ?? fa???µe?? t?? ?pa???? ?e??? ????? se ???e
  se??da ???µ??eta? es?te???? tµ?µat?p???s?.
• To p????? t?? se??d?? pe??????eta? ap? t? µ??e???
  t?? ap?µ???t???? µ??µ??, ?a? ap?te?e? t? ?e??µe??
  ??d? (bucket) p?? e??a? ? ?????? µ???da
  p??sp??as?? st? d?s??.

32
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• H e????? t?? ?at??????? µe?????? ??d?? e??a?
  s?µa?t??? ??a t? ße?t?st?p???s? t?? ???s?? t??
  ????? t?? d?s???.
• ?st? ?t? t? µ??e??? e???af?? e??a? 160 bytes, e??
  t? µ??e??? t?? se??da? e??a? 256 bytes
• ?? e???af?? ap????e???ta? e? µ??e? se d?? se??de?
  (a???µ??? ??st?? p??sp??as??),
• ???e e???af? ap????e?eta? se µ?a se??da (a???µ???
  ??st?? se ???? ???? ?pa???? ?e??? ?????).

33
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???
34
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ?? p?s?st? ???s?µ?p???s?? t?? ????? d?deta? ap?
• ?p?? Ppb e??a? ? a???µ?? t?? se??d?? a?? ??d?
• ?a? S e??a? t? µ??e??? t?? t?µ?a se bytes.

35
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ?????? a?a??t?s?? (seek), Tseek µeta????s? t??
  ?efa??? ep??? ap? t?? ?at?????? t?????.
• ?????? pe??st??f???? ?a??st???s?? (rotational
  latency), Trot a?aµ??? µ???? ? ?at??????? t?µ?a?
  pe??se? ??t? ap? t?? ?efa??.
• ?????? ?etaf???? (transfer) ded?µ????, Ttrans ?
  ?efa?? d?aß??e? ? ???fe? ded?µ??a.
• G?a t? ????? p??sp??as?? (access) ?s??e? Ttotal
  Tseek ?rot ?trans

36
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ?? ? ???s? ?e????e? ?t? ???eta? µe ß?s? t?? ??d?,
  t?te ? ?????? se???a??? a?????s?? e??? a??e???
  ?s??ta? µe
• ?p?? bk e??a? ? a???µ?? t?? ??d?? t?? a??e???
  ?a? dtt e??a? ? ?????? µetaf???? ded?µ????
• O ?????? t??a?a? a?????s?? t?? a??e??? e??a?
• ?e??e?ta? aµe??t?? t? µ??e??? t?? ep??efa??da?
• ?p?t??eta? ?t? ?? e???af?? ????? sta?e?? µ????.

37
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ? a??a?? t?? µe?????? t?? ??d?? de? ep?d?? st??
  ta??t?ta t?? se???a??? a?????s??
• ? a???s? t?? µe?????? t?? ??d?? a????e? t??
  ta??t?ta t?? t??a?a? p??sp??as?? t?? a??e??? µe
  ß?s? t?? ??d?, e?? µe???e? t?? ta??t?ta t??
  t??a?a? p??sp??as?? t?? a??e??? µe ß?s? t??
  e???af?

38
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ?? ? ???s? ???eta? µe ß?s? t?? e???af??, t?te ?
  a?t?st????? t?p?? e??a?
• G?a t?? p??sp??as? µ?a? e???af?? p??pe? ?a
  µetafe??e? st?? ????a µ??µ? ??a? ????????? ??d??
  a?t? µ?a? ? d?? se??d??

39
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ?? ? epe?e??as?a t?? a??e??? ???eta? ?????? ?at?
  t??a?? t??p?, t?te de? s?µf??e? ?a ?µad?p?????ta?
  p????? se??de? se ??a? ??d?.
• ? e????? t?? ?at??????? a???µ?? se??d?? a?? ??d?
  e??a? ??a p???d??stat? p??ß??µa.

40
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ? d?a?e???st?? p??pe? ?a ??????e? p??e? se??de?
  e??a? ?ate???µµ??e? ?a? p??e? e?e??e?e?. ?p??????
  d?? te??????
• µe ???s? µ?a ??sta? ??a t?? d?e????se?? t??
  e?e??e??? se??d??, ?p?? ???eta? µe t? s??????
  s???p?d??? (garbage collection) ap? ??a
  ?e?t??????? s?st?µa, ?
• µe ???s? e??? d?ad???? p??a?a, ?p?? ta 1 ?a? 0
  a?t?st?????? st?? ?ate???µµ??e? ?a? st??
  e?e??e?e? se??de?, a?t?st???a.

41
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ? tµ?µat?p???s? t?? d?s??? e??a? ? d?ad??as?a
  ?at? t?? ?p??a ?p???e? s??????? e?e??e??? ?????
  ?µ?? e??a? µ? p?a?t??? e?µeta??e?s?µ??.
• ?a a??e?a ???????ta? se e?t?se?? (extents) ?p??
  ???e ??tas? ?ata?aµß??e? ??a s???e???µ??? µ????
  t?? d?s???
• ?? e?t?se?? e??a? ?s?µe???e?? ?a? p???????? se
  p????? ap? µ?a µ???? µe????? de??de?.

42
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ????? d?s???

• ???a? p??? ap?te?esµat??? ap? ?p??? pa?a?????sµ??
  ta µe???a a??e?a ?a ep?µe?????ta? se e?t?se?? p??
  ap????e???ta? se d?af??et????? d?s????. ?
  ?ata??µ? a?t? ???eta? ?e??? ? s??des? (spanning).
  
• ??a e?sa??µe?? e???af? µp??e? ?a µ? ???? se
  ??p??a ??tas?. ??te t? s?st?µa pa?a???e? st?
  a??e?? µ?a ep?p???? ??tas? µe t??p? ad?afa?? ??a
  t? ???st?. ???µ?, t? s?st?µa µp??e? µ?a ?de?a
  ??tas? ?a t? d?a??se? se ??p??? ???? a??e??.

43
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ? s??p?? t?? ap?µ???t???? µ??µ?? (buffer
  memories) e??a? ? ?µa??p???s? t?? ???? t??
  ded?µ???? µeta?? t?? ???????? ????a? µ??µ?? ?a?
  t?? ß?ad?te??? pe??fe?e?a??? s?s?e???, ?a? ?e????
  d?a??????ta? se d?? t?p???
• t?? ?????? (hardware buffers), p??
  ???s?µ?p?????ta? e???tata ??a t? d?a?e???s? t??
  ?d?a?te?a a???? pe??fe?e?a??? s?s?e???, ?a?
• t?? ????sµ???? (software buffers), p?? e??a?
  tµ?µata t?? ????a? µ??µ??.

44
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• S??p?? t?? ap?µ???t???? (buffer) µ??µ?? e??a? ?
  ?µa??p???s? t?? ???? t?? ded?µ???? µeta?? t??
  ???????? ????a? µ??µ?? ?a? t?? ß?ad?te???
  pe??fe?e?a??? s?s?e???.
• ?? ?????? (hardware buffers) ???s?µ?p?????ta?
  e???tata ??a t? d?a?e???s? t?? ?d?a?te?a a????
  pe??fe?e?a??? s?s?e???.
• ???s?µ?p?????ta? st?? a?a???st???? µ???de?
  ?a?t?ta?????,
• s?µe?a ???s?µ?p?????ta? st??? e?t?p?t?? ?a?
  ß??s???ta? µ?sa st?? e?e??t? t???.
• ?? ????sµ???? (software buffers) e??a? tµ?µata
  t?? ????a? µ??µ??.

45
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ?? ????sµ???? ap?-µ???t???? µ??µe? e??a?
  apa?a?t?t? s?stat??? ???e S???.

• ? ap?µ???t??? µ??µ? e??a? ??µµ?t? t?? ????a?
  µ??µ?? ?p?? t?p??et???ta? p??s????? ap? t?
  d?a?e???st? t?? ap?µ???t???? µ??µ?? ta ded?µ??a
  p?? ?????ta? ap? t? d?s?? µ???? ?a ???e? ?
  epe?e??as?a t???.

46
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??
? d?a?e???st?? t?? ap?µ???t???? µ??µ?? e??a?
?pe?????? ??a t?? teµa??sµ? t?? µ??µ?? se ??a
s????? p?a?s??? (frames), ?p?? t? µ??e??? ???e
p?a?s??? e??a? ?s? p??? t? µ??e??? t?? se??da?,
e?? t? s????? t?? p?a?s??? ???µ??eta? de?aµe??
µ??µ?? (buffer pool).
47
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??
?a a??te?a st??µata t?? s?st?µat?? ep??????????
µe t? d?a?e???st? t?? ap?µ???t???? µ??µ?? ?a?

• t?? ??t??? ??p??a se??da, p?? µp??e? ?d? ?a
  ß??s?eta? se ??p??? p?a?s??, a????? p??pe? ?a
  p??spe?as?e? ap? t? d?s??, ?
• t?? pe????? ??a µ???µa ?t? de? ??e?????ta? p????
  ??p??a se??da, ?p?te t? p?a?s?? µp??e? ?a
  e?e??e???e?,
• t?? pe????? ??a µ???µa ??a ??p??a e??µ???s? p??
  ??e? ep???e? se ??p??a se??da, ?p?te ? e??µ???s?
  a?t? p??pe? ?a pe??se? st?? a?t?st???? se??da t??
  d?s???.

48
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??
? d?a?e???st?? ??????e? ??a ???e p?a?s?? p?se?
f???? ??e? ??t??e? ????? ?a e?e??e???e? ap? t?te
p?? ? a?t?-st???? se??da t?p??et????e st??
ap?µ???t??? µ??µ?, ?a? a? t? p?a?s?? e??a?
ß??µ??? (dirty), d??ad? a? ??e? e??µe???e?. ??t?
ep?t?????eta? µe t? ß???e?a t?? ?e??µe??? µet??t?
?a?f?µ?t?? (pin_count) ?a? t?? ?e??µe??? ß??µ????
bit. ?????? ?? d?? µetaß??t?? pa?????? t?µ? ?s?
µe µ?d??.
49
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ?ta? ??te?ta? µ?a se??da ? d?a?e???st?? ???e? ta
  e???
• ?????e? a? ? ????? t?? ap?µ???t???? µ??µ??
  pe????e? t? se??da. ?? de? ?p???e?, ?
  d?a?e???st?? t? f???e?
• ep????e? ??a p?a?s?? p??? a?t??at?stas? ?a?
  a????e? t? µet??t? pin_count ?at? 1,
• a? t? ß??µ??? bit t?? p??? a?t??at?stas? p?a?s???
  e??a? 1, ???fe? t?? se??da st? d?s??,
• d?aß??e? t? se??da ?a? t?? t?p??ete? st? p???
  a?t??at?stas? p?a?s??.
• ?p?st??fe? t? d?e????s? t?? p?a?s??? p?? pe????e?
  t? se??da.

50
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ?ta? µ?a se??da ß??s?eta? se ??a p?a?s?? ?a?
  e??a? ? se??da ep?µe??? ??t?s??, t?te ? µet??t??
  ?a?f?µ?t?? a????eta? ?at? ??a ?a? µe???eta? ?ta?
  ???e? µ???µa ?t? ? se??da de? e??a? p???? ???s?µ?
• ?ta? µ?a se??da de? ß??s?eta? se ??p??? p?a?s??
  ?a? e??a? ? se??da ep?µe??? ??t?s??, t?te
  ep????eta? ??a p?a?s?? ??µa ??a t?? t?p???t?s?
  t??.

51
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ?? ??µa ep????eta? µeta?? t?? p?a?s??? µe
  µ?de???? µet??t? ?a?f?µ?t?? efa?µ????ta? µ?a
  p???t??? a?t??at?stas?? se??d?? (page
  replacement).
• ???? e?e??e???e? ? ????? t?? ??µat?? p??pe? ?a
  e?e???e? t? ß??µ??? bit. ?? t? bit a?t? e??a? 0,
  t?te p???µat? t? p?a?s?? e?e??e???eta?, e?? a?
  e??a? 1 t?te t? pe??e??µe?? t?? p?a?s???
  ap????e?eta? st?? a?t?st???? se??da t?? d?s???.
• ?ta? de? ?p???e? se??da µe µ?de???? µet??t?
  ?a?f?µ?t??, ? ??a a?t?s? p??pe? ?a pe??µ??e? ?a?
  p??a??? ?a ap????f?e?.

52
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ? d??at?t?ta p??ß?e??? t?? µe????t???? ??t?s??
  µp??e? ?a ???s?µ?p????e? µe s??p? t? ße?t??s? t??
  ap?te?esµat???t?t?? t?? sta e??? s?µe?a
• µe t?? ep????? t?? ?at??????? p?a?s??? ??a t?
  ???? t?? ??µat??,
• µe t?? ep????? t?? ?at??????? st??µ?? ??a t??
  ap????e?s? t?? ß??µ???? se??d?? st? d?s??, ?a?
• µe t?? p??-p??sp??as? (prefetching) se??d?? ap?
  t? d?s?? p??? a??µ? a?t?? ??t?????.

53
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ? p??-p??sp??as? ße?t???e? s?µa?t??? t?? ep?d?s?
  t?? s?st?µat?? ?ta? de? ??t???ta? ??e? t??
  se??de? t?? d?s??? ?s?p??a?a, a??? ?? a?t?se??
  est?????ta? ?????? se µe????? pe?????? ded?µ????.
  
• ??t? ???µ??eta? t?p???t?ta (locality), ?a? ?d??e?
  se a???s? t?? ????? ep?t???a? (hit ratio), d??ad?
  t?? ????? t?? a???µ?? a?t?se?? p?? apa?t??ta?
  ????? p??sp??as? st? de?te?e???sa µ??µ? p??? t??
  a???µ? t?? s???????? a?t?se??.
• ? p??-p??sp??as?
• ße?t???e? t?? ep?d?s? ?ta? ????µe se???a??
  p??sp??as?, e?? f???e? ?ta? ????µe t??a?a
  p??sp??as?,
• s??te?e? st? µe??s? t?? µ?s?? ?????? p??sp??as??
  t?? se??da?.

54
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ? ???s? t?? µ??µ?? ???eta? ap?te?esµat???te??
  ?ta? µetaf????ta? ded?µ??a ta?t?????a ap? t?
  pe??fe?e?a?? s?s?e?? p??? t?? µ??µ? ?a? ap? t?
  µ??µ? st?? pe????? t?? p?????µµat?? t?? ???st?
  (user program area).
• ? µ???d?? single buffering ???p??e?ta? µe ??a
  µ??a??sµ? ???????? ??sta? µe d?? de??te?
• ? p??t?? de???e? t?? p??t? d?a??s?µ? e???af? ??a
  t? p????aµµa efa?µ????,
• ? de?te??? de???e? t?? p??t? d?a??s?µ? ??s? ??a
  ap????e?s? e???af?? ap? t? de?te?e???sa s?s?e??.

55
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• H te????? double buffering ???s?µ?p??e?ta? st?
  se???a?? p??sp??as?.
• ?a??de??µa
• ?st? ?t? ? ap?µ???t??? µ??µ? ap?te?e?ta? ap? 2
  p?a?s?a
• ?st? ?t? ta d?? p?a?s?a ?eµ????? µe t?? p??te? 2
  se??de? t?? a??e???
• µ???? ?????????e? ? epe?e??as?a t?? p??t??
  p?a?s???, t?te a?t? ?a?a?eµ??e? µe t? pe??e??µe??
  t?? t??t?? se??da?
• se ???e ??????? st??µ? t? ??a p?a?s?? d??eta?
  ded?µ??a, e?? t? ???? s?µµet??e? st?? epe?e??as?a
• ? te????? a??a??? t?? ????? ???µ??eta? a?ta??a??
  ap?µ???t???? µ??µ??.

56
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??
57
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ?ta? ?? ?p?????sµ?? e??a? s???et??, t?te de?
  ????µe ?eaµat??? ap?te??sµata
• St? ep?µe?? pa??de??µa ?p???t??µe ?t? ? ??????
  CPU t??p??s??? ap? ????? ?/?.

58
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
??a?e???s? ap?µ???t???? µ??µ??

• ?? ?? ap?µ???t???? µ??µe? ????? µ??e??? ?s? µe
  µ?a ?t?a?t?, t?te ? ?????? p?? apa?te?ta? ??a t?
  se???a?? epe?e??as?a t?? a??e??? e??a?
• ?p?? t e??a? ? ????? t?? ?????? CPU p??? t? ?????
  e?s?d??/e??d??
• b ? a???µ?? t?? ??d?? t?? a??e???
• ebt ? p?a?µat???? ?????? µetaf???? se??da?

59
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
???????µ?? a?t??at?stas?? se??d??

• ? ???st?te?? p???t??? a?t??at?stas?? se??d??
  e??a? ? ep????? t?? ????te?? p??sfata
  ???s?µ?p???µ???? (least recently used, LRU)
• ???p??e?ta? µe µ?a ????? ?p?? t?p??et???ta? ??
  d?e????-se?? t?? p?a?s??? µe µet??t? ?a?f?µ?t??
  ?s? µe µ?d??,
• ?? ??µa ep????eta? t? p?a?s?? st? ?efa?? t??
  ?????.
• O??????a?? (clock) p???t???
• ??e? t?? ?d?a s?µpe??f??? µe t?? LRU µe µ????te??
  ??st??
• st????eta? se µ?a µetaß??t? current p?? ?e??e?
  ??????? ??a ta p?a?s?a
• ?ta? ? µet??t?? ?a?f?µ?t?? e??a? gt0, t?te ?
  µetaß??t? a????eta? ?at? ??a µ???? ?a ß?e?
  p?a?s?? µe µet??t? ?a?f?µ?t?? 0.

60
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
???????µ?? a?t??at?stas?? se??d??

• ?? p???t???? p?? e?et?st??a? de? e??a? ??
  ?a??te?e?, e?d??? a? p????? a?t?se?? ???st??
  ??t??? se???a?? p??sp??as?.
• ?a??de??µa
• ?st? ap?µ???t??? µ??µ? 10 p?a?s??? ?a? p???
  se???a?? p??sp??as? a??e?? µe 11 ? pe??ss?te?e?
  se??de?,
• µe t?? LRU ???e se???a?? p??sp??as? ?a p??pe? ?a
  d?aß??e? ??e? t?? se??de? t?? a??e???.
• St?? pe??pt?s? a?t? p?? ???µ??eta? se???a??
  p??µµ??a (sequential flood), ? LRU e??a? ?
  ?e???te?? p???t??? a?t??at?stas?? se??d??.

61
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
???????µ?? a?t??at?stas?? se??d??

• ???e? p???t???? a?t??at?stas?? se??d?? e??a?
• ???a?a (random),
• ?e??ss?te?? p??sfata ???s?µ?p???µ??? (most
  recently used - MRU),
• ???t? e???µe?? p??t? a?t??a??st?µe?? (first-in
  first out - FIFO).

62
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
???p???t?s? a?t?se??

• ? e?e??t?? d?s??? d?a??te? µ?a ???? e??p???t?s??
  (service queue) a?t?se??, ?p?? ap????e???ta?
  a?t?se?? p??? p??sp??as?.
• G?a t?? e??p???t?s? µ?a? a?t?s?? apa?te?ta?
  s???????? ?????? TseekTrotTtrans, ?p??
  s?µa?t???te??? e??a? ? ?????? Tseek.
• ?? µ???d?? e??p???t?s? p??spa???? ?a
  e?a??st?p???-s??? t? ????? Tseek.

63
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
???p???t?s? a?t?se??

• ?? ?????te?e? µ???d?? e??p???t?s?? e??a?
• ???t? e???µe??, p??t? e??p??et??µe?? (first come,
  first served - FCFS),
• ???ta ? µ????te?? a?a??t?s? (shortest seek time
  first - SSTF),
• S???s? (SCAN),
• Look.

64
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
S?????

• ? f?s??? ??????s? t?? ded?µ???? t?? ß?s??
  s?et??eta? ?µesa µe t?? ap?d?s? t?? s?st?µat??.
• G?a t? ???? a?t?, e?te????ta? ap? t? S??? p?????
  ?e?t?????e? d?a?e???s?? a??e??? p?? pa?ad?s?a??
  ß??s???ta? st? d??a??d?s?a t?? ?S.

65
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
S?????

• ?a ded?µ??a t?? ß?s?? ap????e???ta? se a??e?a.
• ???e a??e?? ap?te?e?ta? ap? ??a s????? e?t?se??.
• ? ??tas? d?a?????eta? se se??de?, ?a? t????
• ???e se??da pe????e? ??a s????? e???af?? sta?e???
  ? µetaß??t?? µ?????, a?????a µe t?? ???p???s?.
• ? µetaf??? ded?µ???? ap?/p??? t? de?te?e???sa
  µ??µ? p?a?µat?p??e?ta? µe t? ß???e?a ap?µ???t????
  µ??µ??.

66
?ef??a?? 11 F?s??? ??????s? ??se?? ?ed?µ????
S?????

• ? µ??µ? ap?µ???s?? e??a? tµ?µa t?? ????a? µ??µ??,
  t? ?p??? ???s?µ?p??e?ta? ap???e?st??? ap? t?
  S???.
• ? a?a??t?s? ded?µ???? p?a?µat?p??e?ta? p??ta st?
  µ??µ? ap?µ???s??, ?a? µ??? se pe??pt?s? ap?t???a?
  ep??e??e?ta? p??sp??as? st? de?te?e???sa µ??µ?.
• ?ts? µe???eta? ? ?????? epe?e??as?a?, ?a??? µ?a
  p??sp??as? st? d?s?? ??e? µe?a??te?? ???????
  ??st?? se s??s? µe µ?a p??sp??as? st?? ????a
  µ??µ?.