IOPS vs. Mbytes/sec

IOPS

• The standard unit of measurement for I/O operations per second. Includes all reads and writes.
• This is how you rate a I/O stack components ability to process small block random I/O requests.
• Used to describe I/O rate driven applications (OLTP, random I/O ) Mbytes/s


Mega”Bytes” per sec

• Used to measure large block sequential transfer rates, with no response time characterization
• Used to describe data rate driven applications (DSS, OLAP)
• Transaction/s – its anything you claim it to be.

Oracle query to gather this data from your database:

set lines 250
set pages 9999
spool sysmetric_outp.log
alter session set nls_date_format=’dd-mm-yyyy hh24:mi’;
select min(begin_time), max(end_time),
sum(case metric_name when ‘Physical Read Total Bytes Per Sec’ then average end)
Physical_Read_Total_Bps,
sum(case metric_name when ‘Physical Write Total Bytes Per Sec’ then average end)
Physical_Write_Total_Bps,
sum(case metric_name when ‘Redo Generated Per Sec’ then average end)
Redo_Bytes_per_sec,
sum(case metric_name when ‘Physical Read Total IO Requests Per Sec’ then average end)
Physical_Read_IOPS,
sum(case metric_name when ‘Physical Write Total IO Requests Per Sec’ then average end)
Physical_write_IOPS,
sum(case metric_name when ‘Redo Writes Per Sec’ then average end) Physical_redo_IOPS,
sum(case metric_name when ‘Current OS Load’ then average end) OS_LOad,
sum(case metric_name when ‘CPU Usage Per Sec’ then average end)
DB_CPU_Usage_per_sec,
sum(case metric_name when ‘Host CPU Utilization (%)’ then average end) Host_CPU_util, –
NOTE 100% = 1 loaded RAC node
sum(case metric_name when ‘Network Traffic Volume Per Sec’ then average end)
Network_bytes_per_sec,
snap_id
from dba_hist_sysmetric_summary
group by snap_id
order by snap_id;
spool off

[source: CERN]