2.04.2016

Storage difference between 2 identical Exa boxes. How and why?

We noticed around 1.6TB storage difference between two Eight (1/8) Exadata boxes while configuring Data Guard. Wondered what went wrong. The Exa box configured for DR was around 1.6TB short compare to the other Exa box. Verified the lun, physical disk and grdidisk status on a cell, which showed active/online status. The tricky part on Exadata is, everything has to be active/online across all cell storage servers. We then figured-out that grid disk status on the 3rd cell storage server was inactive. After making them active on the 3rd cell server, everything become normal, i mean, the missing 1.6TB space appeared.
When you work with Exadata, you need to verify all cell storage servers to confirm the issue, rather than just query things over just one cell server.

1.12.2016

Gather system stats on EXADATA X4-2 throws an ORA-20001,ORA-06512

After a recent patch deployment on Exadata X4-2 system, the following error encountered whilst gathering system stats with Exadata mode (dbms_stats.gather_system_stats('EXADATA')):

SQL> exec dbms_stats.gather_system_stats('EXADATA');
BEGIN dbms_stats.gather_system_stats('EXADATA'); END;

*
ERROR at line 1:
ORA-20001: Invalid or inconsistent input values
ORA-06512: at "SYS.DBMS_STATS", line 27155
ORA-06512: at line 1

It appears to be a BUG, and the following workaround should resolve the issue:

(1) As SYS user execute the scripts below:

SQL> @?/rdbms/admin/dbmsstat.sql
SQL> @?/rdbms/admin/prvtstas.plb
SQL> @?/rdbms/admin/prvtstat.plb
SQL> @?/rdbms/admin/prvtstai.plb

(2) Then, re-run your DBMS_STATS call:

exec dbms_stats.gather_system_stats('EXADATA');

Indeed this worked for us and hope this would work for you as well.

8.19.2015

Shrink/Grow Exadata diskgroups

One of the important tasks that I foresee after an initial Exadata deployment is, mostly prior to DB in production, is to balance/resize the Exadata diskgroups (DATA & RECO).  Generally, the space is distributed as 80(DATA), 20(RECO) or 40(DATA), 60(RECO), depending on the database backup option you choose while deploying. In one of our Exadata setups, we don't need such a huge RECO size, hence, we shrunk the RECO size and increased the DATA diskgroup size. I am pretty sure, many of you might have done and want to do the same. However, shrinking/rebalancing the space is not like a normal ASM resize operation on Exadata, it needs some special consideration and tasks. The following Oracle Support Notes has the better explanation and examples to achieve the task.

Example of dropping RECO diskgroup and adding the space to DATA diskgroup (Doc ID 1905972.1)
NOTE:1465230.1 - Resizing Grid Disks in Exadata: Example of Recreating RECO Grid Disks in a Rolling Manner
How to increase ASM disks size in Exadata with free space in cell disks (Doc ID 1684112.1)
Resizing Grid Disks in Exadata: Examples (Doc ID 1467056.1)



7.13.2015

Oracle Exadata Database Machine Implementation Essentials - Exam cleared

I have cleared my 'Oracle Exadata Database Machine Implementation Essentails' exam on 9-July-2015. This has been really one of the good weeks of my life. My latest Oracle book, 'Oracle Exadata Expert's Handbook' was released on 6-July-2015, passed the exam on 9-July-2015, can't ask for more.

Thank you my dears and nears.

Oracle Exadata Expert's Handbook - is out now

I am happy to share a good news with the Oracle community today. Our latest book 'Oracle Exadata Expert's Handbook' authored by well-known Oracle gurus is hit the racks on 6-July-2015.

Contents if you wish know what has been covered in this book



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We hope the book will meet your expectations and will add more knowledge your skill set.