When using autoextend on tablespaces, the oracle tablespace rule and extents rule fire but it looks if they are comparing the space left in the current extent and not the MaxSize that a tablespace can grow to. The end result is many alerts are being fired when there is plenty of growth left in the tablespaces.
The rule is simply based on the Severity column in the complex observation. The agent takes the values from the ASPs, and depending on which tablespaces that is specified in the ASPs, applies the thresholds.
There are three default primary ASPs that are applied to all tablespaces not otherwise specified A warning, critical and fatal percentage. Once these percentages have been met, the row committed to Foglight will have either a Warning, Critical, or Fatal in the severity Column.
Then, if the desire is to either ignore a tablespace or override these default values, the need would be to open up the secondary ASP, Tablespace Specification List and specify the tablespace and whether they want to ignore it or provide different thresholds.
In Foglight 4 on the FMS console | Right click on the Oracle agent | edit ASP's | Click on the Space Monitoring (Tablespaces) tab
In Foglight 5 on the Web Console | Under Dashboards | Administration | Agents | Agent Status | highlight Oracle agent | Edit properties | Space Monitoring (Tablespaces)
This allows the user to identify important or un-important tablespaces within their database and raise alerts appropriately.
A tablespace is made up of many datafiles each datafile has a MAXSIZE attribute. An autoextensible datafile can and will automatically grow when more space is needed by Oracle until it either reaches MAXSIZE or the filesystem the datafile is on runs out of freespace. Thus, the Oracle agent uses some complex algorithms to determine the REAL (read that as POTENTIAL) size of these autoextensible datafiles by looking at the freespace on the disk and comparing it to the MAXSIZE attribute, and summing this up for the tablespace