v$osstat tips 

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 the server:

select
   stat_name,
   value,
   osstat_id,
   comments,
   cumulative
from
   gv$osstat
where
   inst_id = userenv('instance')

Oracle has several views that collect OS information, namely v$osstat, stats$osstat, stats$osstatname and dba_hist_osstat.

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 ODS bottleneck. 

select * from v$osstat;
select * from dba_hist_osstat;
select * from dba_hist_sytatem_event;

-- If you don't want to pay the fee to purchase AWR, use my vmstat table

select * from stats$vmstat

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