Configuration parameters that affect sbspace I/O

The SBSPACENAME, BUFFERPOOL, and LOGBUFF configuration parameters affect the I/O performance of sbspaces.

The SBSPACENAME configuration parameter indicates the default sbspace name if you do not specify the sbspace name when you define a column of data type CLOB or BLOB. To reduce disk contention and provide better load balancing, place the default sbspace on a separate disk from the table data.

The BUFFERPOOL configuration parameter specifies the default values for buffers and LRU queues in a buffer pool for both the default page size buffer pool and for any non-default pages size buffer pools. The size of your memory buffer pool affects I/O operations for smart large objects because the buffer pool is the default area of shared memory for these objects. If your applications frequently access smart large objects, it is advantageous to have these objects in the buffer pool. Smart large objects only use the default page size buffer pool. For information about estimating the amount to increase your buffer pool for smart large objects, see The BUFFERPOOL configuration parameter and memory utilization.

By default, the database server reads smart large objects into the buffers in the resident portion of shared memory. For more information on using lightweight I/O buffers, see Lightweight I/O for smart large objects.

The LOGBUFF configuration parameter affects logging I/O activity because it specifies the size of the logical-log buffers that are in shared memory. The size of these buffers determines how quickly they fill and therefore how often they need to be flushed to disk.

If you log smart-large-object user data, increase the size of your logical-log buffer to prevent frequent flushing to these log files on disk.

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