Tips and Tricks for Installing Ops Center 12c R2 (PSU2)

In one of my old posts, I wrote a step by step guide to install Ops Center on Linux. I still get questions about installation, mostly about installing repository Database. So I have downloaded latest patch set version if anything has changed about installation, and decided to write tips and tricks to help Ops Center users. If you have read my previous blog, or you are already an Ops Center user, you may remember (more...)

Physical IO on Linux

I posted a fair amount of stuff on how Oracle is generating IOs, and especially large IOs, meaning more than one Oracle block, so > 8KB. This is typically what is happening when the Oracle database is executing a row source which does a full segment scan. Let’s start off with a quiz: what you think Oracle is the maximum IO size the Oracle engine is capable of requesting of the Operating System (so the (more...)

How to setup git as a daemon

This is a quick post on using git on a server. I use my Synology NAS as a fileserver, but also as a git repository server. The default git package for Synology enables git usage on the command line, which means via ssh, or via web-DAV. Both require a logon to do anything with the repository. That is not very handy if you want to clone and pull from the repository. Of course there are (more...)

Exadata and Bash Shellshock

There has recently been a lot of news about the exploit revealed in the bash shell.  While the fix is very quick to implement, there are a couple of tricks that are required to install this update on an Exadata environment.  According to Oracle support note #1405320.1, Exadata storage server versions 11.2.3.x.x and 12.1.1.x.x are susceptible to the exploit.  On a typical Oracle Enterprise Linux, a simple (more...)

Where is my space on Linux filesystem?

Not Often, I checked about my space after made filesystem on Linux. Today, I have made Ext4 filesystem around 460GB, I found it 437GB only. Some path should be 50GB, but it was available only 47GB.
Thank You @OracleAlchemist and @gokhanatil for good information about it.
Filesystem                   Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup0-U01LV   50G   52M   47G   1% /u01

Reference  - (more...)

Extend linux partition on vmware

It was a quiet day, I worked as System Administrator and installed Oracle Linux on Virtual Machine guest. After installed Operating System, I wanted to extend disk on guest. So, I extended disk on guest. Anyway, I came back in my head what I was supposed to do on Linux then ? 
- Create new disk (and Physical Volume) and then add in Volume Group.
Checked my partition:
[root@mytest01 ~]# fdisk -l (more...)

Switch CentOS to Oracle Linux –

My time has used much with Linux. Some people asked to move from CentOS to Oracle Linux somehow. I used to believe it easy to do like that. Anyway, It'd better to test. 
I focused on 2 links.

Oracle introduces script that can convert CentOS 5 and 6 systems to Oracle Linux. After that run "yum upgrade" again.
[root@test-centos ~]# uname -r
2.6.32-431.29. (more...)

Using Ansible for executing Oracle DBA tasks.

This post looks like I am jumping on the bandwagon of IT orchestration like a lot of people are doing. Maybe I should say ‘except for (die hard) Oracle DBA’s’. Or maybe not, it up to you to decide.

Most people who are interested in IT in general will have noticed IT orchestration has gotten attention, especially in the form of Puppet and/or Chef. I _think_ IT orchestration has gotten important with the rise of (more...)

Grid logging in

Most of the talk about Oracle’s release of is about the InMemory feature, but more things have changed, for example some essential things about loggin in the Grid Infrastructure have changed. Normally in Oracle Grid Infrastructure logging for Grid components was done in $GI_HOME:

oracle@dm01db01(*gridinfra):/home/oracle> cd $ORACLE_HOME/log/`hostname -s`/

There we have the main alert log for GI and several subdirectories for the GI binaries where they write (more...)

Oracle IO wait events: db file sequential read

(the details are investigated and specific to Oracle’s database implementation on Linux x86_64)

Exadata IO: This event is not used with Exadata storage, ‘cell single block physical read’ is used instead.
p1: file#
p2: block#
p3: blocks

Despite p3 listing the number of blocks, I haven’t seen a db file sequential read event that read more than one block ever. Of course this could change in a newer release.

One of the important things (more...)

Clobbering grub.conf is Bad

I’m sharing this in the hope of saving someone from an unwelcome surprise.


I recent upgraded an Exadata system from to Apart from what turns out to be a known bug[1] that resulted in the patching of the InfiniBand switches “failing”, it all seemed to go without a snag. That’s until I decided to do some node failure testing…

Having forced a node (more...)

Changes in Oracle Linux 7

The following is a list of changes I noted during installation of Oracle Linux 7. I imagine the same will apply to Red Hat Enterprise Linux 7, but I haven’t verified that to be the case.

Setting the Hostname

I was accustomed to updating /etc/sysconfig/network with the hostname of my machine as documented here for Oracle Linux 7. I did this and was then surprised to find that my hostname was not picked up. On returning (more...)

Mounting VMWare-Volumes/Disks with Debian

Some time ago a vmware server did not recognize any more a data disk. This disk was formatted with vmfs v3 (enter the vmware server via ssh and type mount..). First thing i did, was creating an image of this disk, to play around without any danger of data loss.

There is a good article how to mount vmfs, but on debian i had to install the package otherosfs.

After i installed this (more...)

What the heck are the /dev/shm/JOXSHM_EXT_x files on Linux?

There was an interesting question in Oracle-L about the JOXSHM_EXT_* files in /dev/shm directory on Linux. Basically something like this:

$ ls -l /dev/shm/* | head
-rwxrwx--- 1 oracle dba 4096 Apr 18 10:16 /dev/shm/JOXSHM_EXT_0_LIN112_1409029
-rwxrwx--- 1 oracle dba 4096 Apr 18 10:16 /dev/shm/JOXSHM_EXT_100_LIN112_1409029
-rwxrwx--- 1 oracle dba 4096 Apr 18 10:16 /dev/shm/JOXSHM_EXT_101_LIN112_1409029
-rwxrwx--- 1 oracle dba 4096 Apr 18 10:23 /dev/shm/JOXSHM_EXT_102_LIN112_1409029
-rwxrwx--- 1 oracle dba 4096 Apr 18 10:23 /dev/shm/JOXSHM_EXT_103_LIN112_1409029
-rwxrwx--- 1  (more...)

Oracle Linux 7 Beta 1 (fixed with CVE-2014-0160 with openssl-1.0.1e-23.0.1.el7)

Last post, I blog about Oracle Linux Beta 1 that I would like to learn more after it has changed to use Systemd targets. In this post, I just wanted to update for some people who have installed Oracle Linux 7 Beta 1 or have been testing it. On Oracle Linux Beta 1, that uses openssl version (openssl-1.0.1e-23.el7) and it's issue about CVE-2014-0160. Users can go Oracle Linux Early Access Downloads and download (more...)

Read Oracle Linux 7 Beta 1

It might be too late posting about Oracle Linux 7 (Beta 1). Just came back from long holidays in Thailand. I think it's very interesting to learn something new in OL7. Users can download it by using OTN account.
Release Note.

After installed it, I tested some a little bit.
[root@ol7beta ~]# cat /etc/oracle-release
Oracle Linux Everything release 7.0 Beta
[root@ol7beta ~]# uname -r
Users can choose to (more...)

Ubuntu upgrade to 12.04: grub timeout does not work anymore

After doing the upgrade and solving some issues with my screen-resolution, another grub problem hit me:
The timeout for booting the standard kernel did not work anymore.
Inside /etc/default/grub
and update-grub, grub worked like
If you need a  good manual  just look here, but this does not help me, too.

After some tries, i did the following:

In /boot/grub/grub.cfg i changed from
terminal_output gfxterm
if [ "${recordfail}" = 1 ] (more...)

Ubuntu upgrade to 12.04: screen only works with 1024×768

After upgrading a laptop-system to 12.04 (precise pangolin) X only starts with a resolution of 1024x768 and not with 1366x768.
I followed many postings and tried many things:
  • add new resolution with xrandr (here)
  • create a xorg.conf file (here)
  • add new drivers (here)
  • ...
But there was only one thing wrong: /etc/default/grub

After changing the following line everything worked:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash i915.modeset=0
(i added (more...)

Automated Linux VM build on ESX

How to automatically install RedHat like (Red Hat, Cent OS, Oracle Enterprise Linux) Linux system on ESX or VirtualBox servers ? There are at least two methods. I have seen VM cloning in lot of places using ESX (VSphere Center) or VirtualBox functionality. Cloning is fine but it required some intervention after clone will be finished (like host rename or IP address change). What if we want to install different releases of systems - well it (more...)

Troubleshooting Oracle DBFS mount issues

On Exadata the local drives on the compute nodes are not big enough to allow larger exports and often dbfs is configured. In my case I had a 1.2 TB dbfs file system mounted under /dbfs_direct/.

While I was doing some exports yesterday I found that my dbfs wasn’t mounted, running quick crsctl command to bring it online failed:

[oracle@exadb01 ~]$ crsctl start resource dbfs_mount -n exadb01
 CRS-2672: Attempting to start 'dbfs_mount' on 'exadb01'