How does EM12c calculate tablespace freespace?

From: Rich Jesse <>
Date: Tue, 2 Jun 2015 09:04:07 -0500 (CDT)
Message-ID: <>

Hey all,

EM popped a "Tablespace MYTBS is 97 percent full" incident last week, but I haven't been able to determine why or how it thinks the tablespace is at 97% capacity.

The target is on AIX. There are no rows in DBA_OUTSTANDING_ALERTS and no tablespace alerts in DBA_ALERT_HISTORY in the target, so I'm guessing this is an EM12c calculation rather than a DB one.

Working from the storage calc listed on MOS 1590051.1, I'm using this query to show "percent full":

FROM dba_tablespaces t,

	SELECT tablespace_name,
		SUM(NVL(bytes,0))/(1024*1024*1024) total_gb
	FROM dba_data_files
	GROUP BY tablespace_name) f,

SELECT tablespace_name, SUM(NVL(bytes,0))/(1024*1024*1024) used_gb FROM dba_segments WHERE TABLESPACE_NAME = 'MYTBS' GROUP BY tablespace_name) s WHERE t.tablespace_name = f.tablespace_name (+) AND t.tablespace_name = s.tablespace_name (+);

It returns a value of about 83.77, which is corroborated by Toad's Schema Browser.

There's much more data for this, but in the interest of brevity, I'll start with this.

Thoughts anyone?


Received on Tue Jun 02 2015 - 16:04:07 CEST

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