Hemant's Oracle DBA Blog
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Hemant K Chitale is an Oracle Database Specialist in Singapore.
Hemant's Oracle DBA Blog
4d ago
In Oracle Grid Infrastructure, the OCR (Oracle Cluster Registry) and Voting "Disks" must be on Shared Storage accessible by all the nodes of the Cluster. Typically, these are on ASM.
In ASM, a DiskGroup is created for the disks that hold the OCR.
Normally, an ASM DiskGroup may use External Redundancy (Mirroring or other protection against Physical Disk or LUN failure is provided by the underlying Storage) or Normal Redundancy (Two-Way Mirroring, i.e. two Disks or LUN devices) or High Redundancy (Three-Way Mirroring with three Disks).
However, for the OCR and Voting "Dis ..read more
Hemant's Oracle DBA Blog
3w ago
DBSAT is Oracle's "Database Security Assessment Tool" that you can get from Oracle Support Document "Oracle Database Security Assessment Tool (DBSAT) (Doc ID 2138254.1)" .
This is the User Guide for the current release (3.1)
It does checks against "proven Oracle Database Security best practices, CIS benchmark recommendations and STIG rules".
See Oracle Support Document "Does DBSAT Scan for all of the STIG And CIS Benchmark Controls? (Doc ID 2651827.1)" for a disclaimer.
Here I demonstrate quick installation :
[oracle@node2 ~]$ cd /u01/app/oracle
[oracle@node2 oracle]$ cd DB ..read more
Hemant's Oracle DBA Blog
1M ago
The Oracle Autonomous Health Framework is described in Support Document "Autonomous Health Framework (AHF) - Including TFA and ORAchk/EXAchk (Doc ID 2550798.1)"
In a recent video I have demonstrated running 24.1 orachk (with "-b" for "Best Practices Check) against a 21.3 RAC Cluster.
Here I demonstrate the installation and execution against a 12.2 non-RAC database.
When you download the 24.1 release of AHF (AHF-LINUX_v24.1.0.zip, approximately 410MB), you have to unzip it and then run ahf_setup. It is preferable to use the default location /opt/oracle.ahf (and precreate a "da ..read more
Hemant's Oracle DBA Blog
1M ago
In my previous post, I have demonstrated how a new service can be created for a Pluggable Database (PDB) in Oracle RAC.
Custom Services are configured as Resources. Thus, in that post, I have demonstrated the custom service "newservice" for the PDB "hemantpdb" being configured in the Cluster.
However, PDBs can also be configured and managed as resources. (see the reference in the Oracle Database Features documentation).
This is the current listing of resources in my 2-node 21c RAC Cluster :
[grid@node1 ~]$ crsctl status resource -t ..read more
Hemant's Oracle DBA Blog
1M ago
On my existing, RAC database I have :
[oracle@node1 ~]$ srvctl status database -db DB21CRAC
Instance DB21CRAC1 is running on node node1
Instance DB21CRAC2 is running on node node2
[oracle@node1 ~]$
[oracle@node1 ~]$ srvctl status service -d DB21CRAC -s hemantpdb
PRKO-2017 : Service hemantpdb does not exist for database DB21CRAC.
[oracle@node1 ~]$ srvctl status service -db DB21CRAC -service hemantpdb -pdb HEMANTPDB
PRKO-2017 : Service hemantpdb does not exist for database DB21CRAC.
[oracle@node1 ~]$
[grid@node1 ~]$ lsnrctl status LISTENER_SCAN1
LSNRCTL for Linux: Version 21.0.0.0.0 - Product ..read more
Hemant's Oracle DBA Blog
1M ago
This is a link to my YouTube playlist of demonstrations on Oracle RAC (12c and 21c ..read more
Hemant's Oracle DBA Blog
2M ago
I've put up a short video that shows a client session connected to a RAC SCAN IP address failing over to the surviving RAC instance when the database node goes down
Video demonstration of RAC Client Query Session and Query Failover
When a client connects to a RAC Instance via a SCAN listener : If the node (Linux in this case) goes down abnormally, Grid Infrastructure does a failover of the SCAN IP address to any of the surviving nodes.
In this demo, I have two connections to two different SCAN IPs, one on node1 and the other on node2 (i.e. two different Linux DB Servers run ..read more
Hemant's Oracle DBA Blog
3M ago
Refreshable Clone PDBs have been available since Oracle 12.2
These are 4 blog posts I had made between Nov-21 and Jan-22 :
1. Refreshable Clone PDB -- 1 Manual Refresh (30-Nov-21)
2. Refreshable Clone PDB -- 2 Datafile Names (04-Dec-21)
3. Refreshable Clone PDB -- 3 The ArchiveLog and ArchParLog files (05-Dec-21)
4. Refreshable Clone PDB -- 4 Converting it to a Read Write PDB (23-Jan-22)
Additionally, here is a recent write-up Refreshable PDB Clones in Data Guard Environments On-premises and on Oracle Cloud  ..read more
Hemant's Oracle DBA Blog
5M ago
The Oracle feature allowing the DBA to put a database in "BACKUP" mode is useful for environments where non-RMAN methods / storage snapshots etc are used to make database backups.
However, there seems to be misconception that datafiles are not updated when the database is in BACKUP mode.
Here is a quick demonstration to disprove it. I first place the database in BACKUP mode and then, from other sessions, start-off transactions and checkpoints and switch logfiles. I then check if the datafile headers are updated and whether the datafiles themselves are updated.
17:55:28 SQL ..read more
Hemant's Oracle DBA Blog
6M ago
I start with a 19c CDB called "ORCLCDB" and PDB "ORCLPDB1" that is present in it.
SQL> col name format a16
SQL> select dbid, name, current_scn from v$database;
DBID NAME CURRENT_SCN
---------- ---------------- -----------
2778483057 ORCLCDB 20906515
SQL> select dbid, guid, name, open_mode from v$pdbs;
DBID GUID NAME OPEN_MODE
---------- -------------------------------- ---------------- ----------
2054948555 88129263B99F4BBDE0530100007F7BDF PDB$SEED READ ONLY
4057974068 8812E29864F47615E05301 ..read more