SINGLEBLKRDTIM	Cumulative single block read time (in hundredths of a second)
PHYBLKRD	Number of physical blocks read
PHYBLKWRT	Number of blocks written to disk, which may be the same as PHYWRTS if all writes are single blocks
WAIT_COUNT	Wait Count

Table 4.13 - Important metrics on file-level I/O in dba_hist_filestatxs

Next, a customized exception report will be examined.  In this simple report called hot_write_files.sql, the dba_hist_filestatxs will be queried to identify hot write datafiles where the file consumed more than 25% of the total physical writes for the instance.  The query compares the physical writes or the phywrts column of dba_hist_filestatxs, with the instance-wide physical writes or statistic# = 55 from dba_hist_sysstat.

This simple yet powerful script allows the Oracle professional to track hot-write datafiles over time, thereby, gaining important insights into the status of the I/O sub-system over time.