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Therefore any DBA should perform Healthcheck for the database By Check the below :

1- Check Alert Log.

Check alert log is very important step, which its Indicate for any Error occurs in Database level, So the Data is always append, don’t forget to rotate alert log or purge if you are using 11g you can use ADRCI tools.
you can find alert log location :

in 10g

SQL> show parameter background_dump_dest;

NAME                                 TYPE        VALUE
———————————— ———– ——————————
background_dump_dest                 string      /u01/app/oracle/admin/orcl/bdump

in 11g

SQL> show parameter diagnostic_dest

NAME                                 TYPE        VALUE
———————————— ———– ——————————
diagnostic_dest                      string      /u01/app/oracle

2.Check Dump_File_szie

As we know Oracle Generate Trace file On OS level, But how Oracle manage their size, all this happened By Parameter Called “Max_dump_File_size” This Parameter define Max Size for OS Disk Space.

SQL> show parameter max_dump_file_size

NAME                                 TYPE        VALUE
———————————— ———– ——————————
max_dump_file_size                   string      UNLIMITED

3.Audit Files

If you are enable Audit Parameter, Or SYSDBA Operation is Enable Oracle Will Start generate audit files which is take significant amount of space. and if you didn’t monitor this space it will prevent you access to oracle database until you remove them.

4.Check TableSpace (System, SysAux , Temp … )

You should monitor tablespace and check the free space and status for these table space and all the tablespace should be monitored to avoid any problem that could occur in the future since it will prevent users continuous their works, the below script check Size for each table space and Free space

SELECT /* + RULE */  df.tablespace_name "Tablespace",
       df.bytes / (1024 * 1024) "Size (MB)",
       SUM(fs.bytes) / (1024 * 1024) "Free (MB)",
       Nvl(Round(SUM(fs.bytes) * 100 / df.bytes),1) "% Free",
       Round((df.bytes - SUM(fs.bytes)) * 100 / df.bytes) "% Used"
  FROM dba_free_space fs,
       (SELECT tablespace_name,SUM(bytes) bytes
          FROM dba_data_files
         GROUP BY tablespace_name) df
 WHERE fs.tablespace_name (+)  = df.tablespace_name
 GROUP BY df.tablespace_name,df.bytes
UNION ALL
SELECT /* + RULE */ df.tablespace_name tspace,
       fs.bytes / (1024 * 1024),
       SUM(df.bytes_free) / (1024 * 1024),
       Nvl(Round((SUM(fs.bytes) - df.bytes_used) * 100 / fs.bytes), 1),
       Round((SUM(fs.bytes) - df.bytes_free) * 100 / fs.bytes)
  FROM dba_temp_files fs,
       (SELECT tablespace_name,bytes_free,bytes_used
          FROM v$temp_space_header
         GROUP BY tablespace_name,bytes_free,bytes_used) df
 WHERE fs.tablespace_name (+)  = df.tablespace_name
 GROUP BY df.tablespace_name,fs.bytes,df.bytes_free,df.bytes_used
 ORDER BY 4 DESC;

OR

SELECT d.STATUS "Status",
d.tablespace_name "Name",
d.contents "Type",
d.extent_management "Extent Management",
d.initial_extent "Initial Extent",
TO_CHAR(NVL(a.bytes / 1024 / 1024, 0),'99,999,990.900') "Size (M)",
TO_CHAR(NVL(a.bytes - NVL(f.bytes, 0), 0)/1024/1024,'99,999,999.999') "Used (M)",
TO_CHAR(NVL((a.bytes - NVL(f.bytes, 0)) / a.bytes * 100, 0), '990.00') "Used %",
TO_CHAR(NVL(a.maxbytes / 1024 / 1024, 0),'99,999,990.900') "MaxSize (M)",
TO_CHAR(NVL((a.bytes - NVL(f.bytes, 0)) / a.maxbytes * 100, 0), '990.00') "Used % of Max"
FROM sys.dba_tablespaces d,
(SELECT tablespace_name, 
SUM(bytes) bytes, 
SUM(decode(autoextensible,'NO',bytes,'YES',maxbytes))
maxbytes FROM dba_data_files GROUP BY tablespace_name) a,
(SELECT tablespace_name, SUM(bytes) bytes FROM dba_free_space 
GROUP BY tablespace_name) f
WHERE d.tablespace_name = a.tablespace_name(+)
AND d.tablespace_name = f.tablespace_name(+)
ORDER BY 10 DESC;

5. Data Files Locations

you should check the location for datafiles to make sure there’s no misunderstanding and check autoextened

SQL> select * from v$dbfile;

to Check if the auto extend is on

SQL> select file_id, tablespace_name, bytes, maxbytes, maxblocks, increment_by, file_name
from dba_data_files where autoextensible = ‘YES’;

6. Redo Log

Redo log is very important components in database since its minimize loss of data in the database Redo log files are used in a situation such as instance failure to recover commited data that has not yet been written to the data file.

SQL> select * from v$logfile;

7. Parameter files

Check Spfile, Or pfile in database to Ensure startup and database parameters

SQL> show parameter pfile ;

NAME                                 TYPE        VALUE
———————————— ———– ——————————
spfile                               string      /u01/app/oracle/product/10.2.0/db_1/dbs/spfileorcl.ora

 8. Backup

You have to Check if the backup Script Run successfully without any problems

RMAN > list backup summary

This is how health check database there’s others things you can do such as indexes,and memory

Thank you
Osama Mustafa