DB2 9.5 - Shrink Tablespace I'm trying to run the following:

db2 alter tablespace TABLESPACE1 reduce

I keep getting errors. As you can see, I have around 50% free pages. I'd like to shrink it in order to reclaim OS disk space.

 Tablespace ID                        = 281
 Name                                 = TABLESPACE1
 Type                                 = Database managed space
 Contents                             = All permanent data. Large table space.
 State                                = 0x0000
   Detailed explanation:
     Normal
 Total pages                          = 8943720
 Useable pages                        = 8943696
 Used pages                           = 4559696
 Free pages                           = 4384000
 High water mark (pages)              = 8914736
 Page size (bytes)                    = 32768
 Extent size (pages)                  = 8
 Prefetch size (pages)                = 24
 Number of containers                 = 3
 Minimum recovery time                = 2014-12-09-16.28.18.000000

  Container ID                         = 0
 Name                                 = /data/db2dat_10/sida1/TABLESPACE1_01.dbf
 Type                                 = File
 Total pages                          = 2981240
 Useable pages                        = 2981232
 Accessible                           = Yes
 Container ID                         = 1
 Name                                 = /data/db2dat_11/sida1/TABLESPACE1_02.dbf
 Type                                 = File
 Total pages                          = 2981240
 Useable pages                        = 2981232
 Accessible                           = Yes
 Container ID                         = 2
 Name                                 = /data/db2dat_12/sida1/TABLESPACE1_03.dbf
 Type                                 = File
 Total pages                          = 2981240
 Useable pages                        = 2981232
 Accessible                           = Yes
I ended up figuring this one out.

Shrink a tablespace with DB2 9.5 is much more difficult.
The reduce and resize command exist but will only work if the high water mark is low.
You cannot use reduce or resize below the HWM size.

You need to use DB2DART -LHWM and have the database deactivated while doing so.