Oracle MVA

Tales from a Jack of all trades

Archive for August 2009

RCU and 11g, the solution…

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After reading up on sqlnet, learning how to trace sqlnet trafic of jdbc-thin database sessions and a lot of agony, Oracle support finally solved the problem with RCU and 11g. A small testprogram in java gave a clue. It turns out the 11g database is too slow in accepting the session. Adding JDBC_LOGON_TIMEOUT with a value larger then 15 in $RCU_HOME/rcu/config/rcu.properties solved the issue.

Sometimes VMWare on my laptop is far from ideal.

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Written by Jacco H. Landlust

August 28, 2009 at 3:54 pm

Posted in RDBMS

Tracing sqlnet in 11g

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When I was still young, you could easily trace a sqlplus session by adding some parameters to the appropriate sqlnet.ora file e.g.:

TRACE_LEVEL_CLIENT=16
TRACE_DIRECTORY_CLIENT=/home/oracle
TRACE_FILE_CLIENT=client
TRACE_UNIQUE_CLIENT=ON
TRACE_TIMESTAMP_CLIENT=ON

When I tried to trace a session with an 11g client, the trace-file didn’t appear in the expected TRACE_DIRECTORY_CLIENT. After a quick look around, it turned out that the trace went to $ORACLE_BASE/diag/clients/user_oracle/host_$NUMBER/trace. Documentation seems clear, so I figured I was going crazy.

My personal lesson for today was: never ever trust your knowledge when you move to a new version of Oracle. Old-school (Oracle 10) tricks are useless, when Oracle introduces a new sqlnet parameter called DIAG_ADR_ENABLED and sets the default to ON. This setting causes Oracle to ignore the TRACE_*_CLIENT parameters.

What is even more sad is that I was not the only person to fall for this caveat.


While reading up some more about tracing I ended up on this page, which provides a utillity for non intrusive jdbc tracing.

Written by Jacco H. Landlust

August 27, 2009 at 10:23 am

Posted in RDBMS

RCU and 11g

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For Oracle Fusion Middleware 11g a repository creation utility (RCU) was provided. I tried to install the repository in a 11.1.0.7 RDBMS on OEL 5 and guess what: it won’t connect to the database. RCU does work with 10.2.0.4.

Time for yet another SR….

Written by Jacco H. Landlust

August 19, 2009 at 5:42 pm

Posted in Weblogic

Creating a failover disk using ascrs

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I certainly hope that installing CRS is no magic anymore for most DBA’s. If it is, please refer to Tim Hall’s website and follow the guide. Certain things in the CRS installation are less documented though:

  1. X-forwarding has been a nuisance for a lot of DBA’s. Refer to this post for some more information about x-forwarding.
  2. I notice that most guides on VMWare ask you to reboot after adding disks. Refer to this post to see how to scan your bus without rebooting.
  3. Shared disks and VMWare Workstation are a pain in the behind.  Obviously someone else felt the same pain too.

I installed CRS on my laptop running VMWare Workstation. The machines are called wls1 and wls2 (guess what this will be in when I’m done 😉 ) After installing CRS, I installed ascrs. ascrs is delivered through the Companion CD of Oracle Fusion Middleware 11g. It installs by just unzipping the ascrs.zip file in your CRS-tree. Next simply call the configure script in the $CRS_HOME/ascrs/bin directory. When you want to use ascrs on all nodes of the cluster, you need to unzip the file on all nodes.

Read the rest of this entry »

Written by Jacco H. Landlust

August 18, 2009 at 3:36 pm

X-forwarding

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In some situations you have a Linux sysadmin that configures a machine for you, but sometimes you have to configure it yourself. If you happen to end up with some raw iron and you want a minimal install of Linux (without a X-server), x-forwarding can be a hassle. Here are some pointers in troubleshooting x-forwarding:

  1. Check for x-forwarding in the /etc/sshd/sshd_config file
  2. Check for x-forwarding in your local ssh-client (like putty )
  3. Check for a running local X-server (Xming is all you need)
  4. Check for a .Xauthority file in your homedirectory (if missing, install xorg-x11-xauth rpm)

Written by Jacco H. Landlust

August 18, 2009 at 11:20 am

Posted in Linux

Why reboot when you could just scan your scsi-bus?

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Whenever I read install guides about Oracle and installations on VM-Ware I always see remarks telling you to reboot your system after you added a disk. This is not necessary.

While your virtual machine is running, click on edit hardware and add a disk. When using VMWare workstation you cannot choose which scsi bus to use. Either try all buss-es, or check the .vmx file. In my case, I called the newdisk newdisk.vmdk, which represents these lines in the vmx file:

scsi0:2.present = “TRUE”
scsi0:2.fileName = “newdisk.vmdk”
scsi0:2.redo = “”

By looking at the code, I can see that the disk has been added to scsi bus 0. Next I scan the bus:

[root@wls2 ~]# echo – – – >/sys/class/scsi_host/host0/scan

This command scans every channel, every target and every lun on the host0 device. When checking dmesg, I notice that the disk is present.

[root@wls2 ~]# dmesg
[..]
Vendor: VMware,   Model: VMware Virtual S  Rev: 1.0
Type:   Direct-Access                      ANSI SCSI revision: 02
target0:0:2: Beginning Domain Validation
target0:0:2: Domain Validation skipping write tests
target0:0:2: Ending Domain Validation
target0:0:2: FAST-40 WIDE SCSI 80.0 MB/s ST (25 ns, offset 127)
SCSI device sdf: 16777216 512-byte hdwr sectors (8590 MB)
sdf: Write Protect is off
sdf: Mode Sense: 5d 00 00 00
sdf: cache data unavailable
sdf: assuming drive cache: write through
SCSI device sdf: 16777216 512-byte hdwr sectors (8590 MB)
sdf: Write Protect is off
sdf: Mode Sense: 5d 00 00 00
sdf: cache data unavailable
sdf: assuming drive cache: write through
sdf: unknown partition table
sd 0:0:2:0: Attached scsi disk sdf
sd 0:0:2:0: Attached scsi generic sg5 type 0

Now I can create a partition using fdisk and start using the disk without rebooting.

Written by Jacco H. Landlust

August 18, 2009 at 9:16 am

Posted in Linux, VMWare

Back again, this time in English…

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After the migration of my dutch blog (http://www.ikkanalles.nl) went wrong,  I switched to wordpress. In the future my dutch domain will link to this blog too. Also I will try to post older relevant post from my dutch blog (after I translated them to English).

The posts on my blog will handle all kinds of technical challenges I experience during my work as MVA. For me it’s an online archive of things to remember, which hopefully can help you as blog reader in your work as Oracle technician. In the end, most of the post are just a reminder for myself 😉

If you have any remarks on a article, please leave a comment.

Let the posting begin!

Written by Jacco H. Landlust

August 12, 2009 at 8:25 am

Posted in Announcements