Oracle Management Database in Grid Infrastructure: -MGMTDB

Oracle,

Why? Why is is now mandatory to have the cluster management database as an Oracle CDB, with a PDB having the same name as the cluster? It’s not that I object to having another 1GB of memory lost to this DB, and up to 10GB of disk in the initial ASM Disk Group. It’s this:

You have called it -MGMTDB

That means I now have directories all over my Linux / Unix structure called (more...)

Oracle on 4096 (4k) sector disks don’t work (ish)

I recently came across 4K (4096 byte) sector drives. They are a fairly new thing and have come about so drives can exceed the 2TB limit imposed by having 512byte sectors. The details behind this can be found here, in much greater detail than I need to understand.

What I do understand is that Oracle doesn’t deal with 4K sectors (4Kn) very well and it shows up in a couple of ways. Don’t get me (more...)

Locking Privileges in Oracle

What permissions do you need to lock rows on an Oracle table?
What about to lock the whole table?

It’s not quite as much as you may think!

Lets have a couple of users; schema_owner and user1

SQL> show user
USER is "SYS"
SQL> create user schema_owner identified by schema_owner;
User created.
SQL> grant connect,resource to schema_owner;
Grant succeeded.
SQL> grant unlimited tablespace to schema_owner;
Grant succeeded.
SQL> create user user1 identified by user1;
User  (more...)

Oracle Cluster Health Monitor – changes in 12.1.0.2

From Oracle 12.1.0.2, the Oracle Cluster Health Monitor becomes an Oracle database by default [replacing the old Berkley DB], and it’s called “-MGMTDB” (note the leading “-“)

cat /etc/oratab

+ASM1:/u01/app/grid:N # line added by Agent
-MGMTDB:/u01/app/grid:N # line added by Agent

It lives on one of the nodes on your RAC cluster and occupied space on Disk Group provisioned during install.

The DB will take about 750MB, so even more (more...)

Oracle 12.1.0.2.0 ACFS on Linux 7 don’t work

I installed OEL 7.1…

uname -a
Linux rac12c01 3.8.13-55.1.6.el7uek.x86_64

Then I installed Grid Infrastructure and Database 12.1.0.2.0 and looked to configure ACFS for the database files, ready for DB create. And it won’t let me. In asmca, the tabs are greyed-out.

Lets just investigate that:

acfsdriverstate supported
ACFS-9459: ADVM/ACFS is not supported on this OS version: 'unknown'

Unknown! Great. This means…patching. After a (more...)

Linux Annoying Defaults

So why does Linux have an alias for “ls” which turns on colour, by default, making some text impossible to read? eh?

alias ls=’ls –color=auto’

To stop this temporarily, you can “unalias ls”, but to stop it permanently for everyone:

vi /etc/profile.d/colorls.sh

comment out the line:

alias ll='ls -l --color=auto' 2>/dev/null
alias l.='ls -d .* --color=auto' 2>/dev/null
# alias ls='ls --color=auto' 2>/dev/null

And that’s it. Cured for life.

 

While I’m on, why (more...)

PC Pro Oracle DBA Article

PC Pro August 2015 CoverI was interviewed recently by UK publication PC Pro magazine for their regular series about IT Careers with regard to database administration (surprise!) The (somewhat abridged!) interview has just appeared in the August 2015 edition of the magazine. I cannot link to the on-line version of the article so here’s my hopefully readable cropped photograph of it.

PC Pro also has an on-line sister publication, Alphr, which is worth a look

PC Pro Neil Chandler DBA


Filed under: Administration (more...)

Cloud Control 12c Discovery Problem

You know when things just don’t quite work as they should, and you spend far longer than you think you should have sorting them out. Well, this was one of them. Burned 20 minutes on this!

I’m running Oracle Enterprise Linux 6.6 with Oracle Enterprise Manager Cloud Control 12.1.0.4, and I’m trying to discover some lovely new targets. Discovery from within OEM is simplicity itself: Delegate privileges from the OEM server, (more...)

Oracle ACE Award

I have just learned that I have been nominated and accepted as an Oracle ACE. I would like to thank Jonathan Lewis for the nomination and Oracle Corp. for the recognition.

O_ACELogo_clr

It’s a tremendous honour for me to receive this award. I just hope I can live up to it by continuing to serve the community, write some more blog posts (here) that people find useful, keep organising the UKOUG RAC, Cloud, Availability and Infrastructure (more...)

Goldengate Data Manipulation – When Inserts & Updates differ

One very useful aspect of Golden Gate is to allow the manipulation of data between the source and the destinations.

One recent problem that I encountered was to alter the data differently for inserts than for updates. This was caused by the receiving system needing to have some default data in columns which may or may not be supplied by the insert or update statements. This is slightly more complex than first imagined: