DB2 V9.5 Tablespace -pages missing and Total pg's not equal to useable pg's

Hi friends -

I created a automatic storage tablespace with a pagesize of 16 K and initial size of 64 MB.

create large tablespace test_tbsp1 pagesize 16k managed by automatic storage autoresize yes initialsize 64 M increasesize 64 M maxsize 2 G no extent size 16 prefetchsize 16 bufferpool test_bp1 file system caching dropped table recovery on

so, the number of pages should be (initialsize/pagesize)= (64 MB /16 K) = 4096 pages

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$ db2pd -db SMPT1 -tablespace 3

Database Partition 0 -- Database SMPT1 -- Active -- Up 0 days 04:48:13

Tablespace 3 Configuration:
Address Type Content PageSz ExtentSz Auto Prefetch BufID BufIDDisk FSC NumCntrs MaxStripe LastConsecPg Name
0x070000006E46AAA0 DMS Large 16384 16 No 16 2 2 Off 9 0 15 TEST_TBSP1

Tablespace 3 Statistics:
Address TotalPgs UsablePgs UsedPgs PndFreePgs FreePgs HWM State MinRecTime NQuiescers
0x070000006E46AAA0 4032 3888 48 0 3840 48 0x00000000 0 0

Tablespace 3 Autoresize Statistics:
Address AS AR InitSize IncSize IIP MaxSize LastResize LRF
0x070000006E46AAA0 Yes Yes 0 0 No 0 None No

Containers:
Address ContainNum Type TotalPgs UseablePgs StripeSet Container
0x070000006E46B500 0 File 448 432 0 /db2/databases/SMPT1/SPTH7/inst4/NODE0000/SMPT1/T0000003/C0000000.LRG
0x070000006E46B660 1 File 448 432 0 /db2/databases/SMPT1/SPTH8/inst4/NODE0000/SMPT1/T0000003/C0000001.LRG
0x070000006E46B7C0 2 File 448 432 0 /db2/databases/SMPT1/SPTH9/inst4/NODE0000/SMPT1/T0000003/C0000002.LRG
0x070000006E46B920 3 File 448 432 0 /db2/databases/SMPT1/SPTH5/inst4/NODE0000/SMPT1/T0000003/C0000003.LRG
0x070000006E46BA80 4 File 448 432 0 /db2/databases/SMPT1/SPTH1/inst4/NODE0000/SMPT1/T0000003/C0000004.LRG
0x070000006E46BBE0 5 File 448 432 0 /db2/databases/SMPT1/SPTH2/inst4/NODE0000/SMPT1/T0000003/C0000005.LRG
0x070000006E46BD40 6 File 448 432 0 /db2/databases/SMPT1/SPTH3/inst4/NODE0000/SMPT1/T0000003/C0000006.LRG
0x070000006E46BEA0 7 File 448 432 0 /db2/databases/SMPT1/SPTH4/inst4/NODE0000/SMPT1/T0000003/C0000007.LRG
0x070000006E46C000 8 File 448 432 0 /db2/databases/SMPT1/SPTH6/inst4/NODE0000/SMPT1/T0000003/C0000008.LRG

========


db2 list tablespaces show detail

Tablespace ID = 3
Name = TEST_TBSP1
Type = Database managed space
Contents = All permanent data. Large table space.
State = 0x0000
Detailed explanation:
Normal
Total pages = 4032
Useable pages = 3888
Used pages = 48
Free pages = 3840
High water mark (pages) = 48
Page size (bytes) = 16384
Extent size (pages) = 16
Prefetch size (pages) = 16
Number of containers = 9

=======

From the above command ouput it is clear that the total number of pages is 4032.

Useable pages are only 3888


Questions :

1) Why are the total number of pages not equal to 4096 ?

2) Why are the total pages not equal to useable pages ?


...


Thanks
Pandith

re: DB2 V9.5 Tablespace -pages missing and Total pg's not equal to useable pg's

there are always header pages, and pages used to keep the chain between pages..
best regards, guy przytula