Monitoring sbspaces with onstat -g smb

The onstat -g smb s option displays sbspace attributes.

Use the onstat -g smb s option to display the following characteristics that affect the I/O performance of each sbspace:

Logging status
If applications are updating temporary smart large objects, logging is not required. You can turn off logging to reduce the amount of I/O activity to the logical log, CPU utilization, and memory resources.
Average smart-large-object size
Average size and extent size should be similar to reduce the number of I/O operations required to read in an entire smart large object. The avg s/kb output field shows the average smart-large-object size in kilobytes. In Figure 1, the avg s/kb output field shows the value 30 kilobytes.

Specify the final size of the smart large object in either of the following functions to allocate the object as a single extent:
- The DataBlade API mi_lo_specset_estbytes function
- The Informix® ESQL/C ifx_lo_specset_estbytes function
For more information about the functions to open a smart large object and to set the estimated number of bytes, see the HCL Informix Enterprise Replication Guide and HCL Informix DataBlade API Programmer's Guide.
First extent size, next extent size, and minimum extent size
The 1st sz/p, nxt sz/p, and min sz/p output fields show these extent sizes if you set the extent tags in the -Df option of onspaces. In Figure 1, these output fields show values of 0 and -1 because these tags are not set in onspaces.

Figure 1. onstat -g smb s output

sbnum 7    address 2afae48 
  Space    : flags    nchk owner    sbname 
             -------- 1    informix client 
  Defaults : LO_LOG LO_KEEP_LASTACCESS_TIME 

  LO     : ud b/pg flags   flags    avg s/kb max lcks 
           2048    0       -------- 30       -1 
  Ext/IO : 1st sz/p nxt sz/p min sz/p mx io sz 
           4        0        0        -1 

  HdrCache : max   free 
             512   0