Question: I use your STATSPACK extension
table for vmstat (stats$vmstat)
and I have been quite happy with my IS stats. I now understand
that Oracle offers a view with limited OS data, called v$osstat.
Is v$osstat better than a custom OS statistics collection?
Answer: Traditionally, Oracle ran in a
vacuum, and you had to go "outside" of Oracle to measure CPU, RAM,
Network and disk spindle I/O bottlenecks. However, Oracle has
now advanced and an instance samples its external environment
placing OS data into v$osstat, dba_hist_system_event.
The v$osstat is created by querying the
gv$osstat view, slicing-off data for each specific instance on
inst_id = userenv('instance')
Oracle has several views that collect OS information, namely
v$osstat, stats$osstat, stats$osstatname and
Still, many DBAs will write custom scripts to gather
OS statistics, collecting from OS tools such as vmstat and
placing the data into STATSPACK extension tables for trend analysis.
Querying from v$osstat ensures that an Oracle
performance problem is not constrained by an external OS
select * from v$osstat;
select * from
select * from dba_hist_system_event;
-- If you don't want to pay the fee to purchase
AWR, use my vmstat table
select * from stats$vmstat