How to check Database Growth for a DB on ASM?

Question

Hi there
I have been using the following script to check the database growth (for DBs on Filesystem):
SELECT b.tsname tablespace_name ,
  MAX(b.used_size_mb) cur_used_size_mb ,
  ROUND(AVG(inc_used_size_mb),2)avg_increas_mb
FROM
  (SELECT a.days,
    a.tsname ,
    used_size_mb ,
    used_size_mb - LAG (used_size_mb,1) OVER ( PARTITION BY a.tsname ORDER BY a.tsname,a.days) inc_used_size_mb
  FROM
    (SELECT TO_CHAR(sp.begin_interval_time,'MM-DD-YYYY') days ,
      ts.tsname ,
      MAX(ROUND((tsu.tablespace_usedsize* dt.block_size )/(1024*1024),2)) used_size_mb
    FROM dba_hist_tbspc_space_usage tsu ,
      dba_hist_tablespace_stat ts ,
      dba_hist_snapshot sp,
      dba_tablespaces dt
    WHERE tsu.tablespace_id    = ts.ts#
    AND tsu.snap_id            = sp.snap_id
    AND ts.tsname              = dt.tablespace_name
    AND sp.begin_interval_time > sysdate-7
    GROUP BY TO_CHAR(sp.begin_interval_time,'MM-DD-YYYY'),
      ts.tsname
    ORDER BY ts.tsname,
      days
    ) a
  ) b
GROUP BY b.tsname
ORDER BY b.tsname;And I think it always gave me good results until I ran this script on a DB (10.2.0.5) on ASM.
Is it because databases on ASM are maintaied differently OR is it that most proabbly there has been no activity on this database in the last 7 days? I even ran this query for last 90/180-days and it still returned me following results:
TABLESPACE_NAME                CUR_USED_SIZE_MB AVG_INCREAS_MB
SYSAUX                                   574.38            .36
SYSTEM                                   514.69              0
DATA                                    1593.25              0
IDX                                         .06              0
UNDOTBS1                                  69.06          -3.84
USERS                                     96.13              0Thanks in advance!

Answer 1

I have no reason to believe tablespaces under ASM are maintained differently, so the most likely explanation is change in DB activity.
What is your AWR retention? The default is 7 days, so if yours is set at the default then running the query for 90/180 days would not give you more information.
If you want to get useful output from your scripts, you might need to adjust the AWR retention and your SYSAUX tablespace respectively.
If the DB is monitored by Oracle Enterprise Manager(OEM), you can do tablespace forecasting based on the metrics collected by OEM. I did a presentation about this (NYOUG,VirtaThon) a while back:
http://iiotzov.files.wordpress.com/2011/08/iotzov_oem_repository.pdf
http://iiotzov.files.wordpress.com/2012/05/oem-repository-a-second-look.doc
Iordan Iotzov