Monitoring sbspaces with oncheck -cS

The oncheck -cS option checks smart-large-object extents and the sbspace partitions in the user-data area.

Figure 1 shows an example of the output from the -cS option for s9_sbspc.

The values in the Sbs#, Chk#, and Seq# columns correspond to the Space Chunk Page value in the -pS output. The Bytes and Pages columns display the size of each smart large object in bytes and pages.

To calculate the average size of smart large objects, you can total the numbers in the Size (Bytes) column and then divide by the number of smart large objects. In Figure 1, the average number of bytes allocated is 2690, as the following calculation shows:

Average size in bytes = (15736 + 98 + 97 + 62 + 87 + 56) / 6 
                    = 16136 / 6
                    = 2689.3

For information about how to specify smart large object sizes to influence extent sizes, see Sbspace extents.

Figure 1. oncheck -cS output

Validating space 's9_sbspc' ...

Large Objects
  ID               Ref Size       Allocced       Creat   Last
  Sbs# Chk#  Seq#  Cnt    (Bytes)    Pages Extns Flags   Modified
  ---- ---- ----- ---- ---------- -------- ----- ----- ------------------------
     2    2     1    1      15736        8     1 N-N-H Thu Jun 21 16:59:12 2007
     2    2     2    1         98        1     1 N-K-H Thu Jun 21 16:59:12 2007
     2    2     3    1         97        1     1 N-K-H Thu Jun 21 16:59:12 2007
     2    2     4    1         62        1     1 N-K-H Thu Jun 21 16:59:12 2007
     2    2     5    1         87        1     1 N-K-H Thu Jun 21 16:59:12 2007
     2    2     6    1         56        1     1 N-K-H Thu Jun 21 16:59:12 2007

The Extns field shows the minimum extent size, in number of pages, allocated to each smart large object.