Buffer cache hit ratio negative


Article ID: 140356


Updated On:


DX Infrastructure Management NIMSOFT PROBES


We have UIM 9.0.2 with oracle agent 5.41 monitoring one oracle RAC version
We enabled the buf_cachehit_ratio checkpoint but sometimes it returns s negative value that should not be correct:


Profile PORTAL, instance portal2, buffer cache hit-ratio (-40.63%) is too low


This is caused by getting a bad value from Oracle.


Release : 9.0.2

Component : UIM - ORACLE

Oracle Database 11g Enterprise Edition Release - 64bit Production


Please consult with your Oracle DBA to see if the result set of this query ever returns a negative number:

SELECT a.value as db_block_gets,

     b.value as consistent_gets,

     c.value as physical_reads,

     d.value as pr_direct,

     e.value as pr_direct_lob,

     f.value as pr_direct_temp_space

 FROM v$sysstat a, v$sysstat b, v$sysstat c, v$sysstat d, v$sysstat e, v$sysstat f

WHERE a.name = 'db block gets' AND b.name = 'consistent gets' AND c.name = 'physical reads' AND d.name = 'physical reads direct'

 AND e.name = 'physical reads direct (lob)' AND f.name = 'physical reads direct temporary tablespace';