The Direct Read and Write Rate graph keeps track of unbuffered I/O¾that is, reads and writes that do not involve the buffer pool, but directly access the database to manage large amounts of data and to perform utility functions.
The graph contains the following series, which measure the direct read and write rates in the database over consecutive monitoring intervals. These rates are based on the number of pages per second.
Read —Plots the direct read rate in the database. Direct reads are used to read VARCHAR and LOB (large object) column data from disk and to perform backups.
Write —Plots the direct write rate in the database. Direct writes are used to write VARCHAR and LOB column data to disk and to perform data loads and restores.
The Statistics tab shows the direct read and write counts used to generate this graph. The names for these statistics begin with either Direct or I/O. These statistics are derived from the DIRECT_READ and DIRECT_WRITE data elements that the DB2 snapshot monitor captures.