Amardeep Sidhu

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Little bit of fun with Oracle and the related technologies...
Updated: 21 hours 1 min ago

ORA-56841: Master Diskmon cannot connect to a CELL

Thu, 2016-05-19 11:45

Faced this error while querying v$asm_disk after adding new storage cell IPs to cellip.ora on DB nodes of an existing cluster on Exadata. Query ends with ORA-03113 end-of-file on communication channel and ORA-56841 is reported in $ORA_CRS_HOME/log/<hostname>/diskmon/diskmon.log. Reason in my case was that the new cell was using different subnet for IB. It was pingable from the db nodes but querying v$asm_disk wasn’t working. Changing the subnet for IB on new cell to the one on existing cells fixed the issue.

 

 

Categories: BI & Warehousing

MRP process on standby stops with ORA-00600

Thu, 2015-08-20 04:03

A rather not so great post about an ORA-00600 error i faced on a standby database. Environement was 11.2.0.3 on Sun Super Cluster machine. MRP process was hitting ORA-00600 while trying to apply a specific archive log.

The error message was something like this

MRP0: Background Media Recovery terminated with error 600
Errors in file /u01/app/oracle/product/11.2.0.3/diag/diag/rdbms/xxxprd/xxxprd1/trace/xxxprd1_pr00_6342.trc:
ORA-00600: internal error code, arguments: [2619], [539], [], [], [], [], [], [], [], [], [], []
Recovery interrupted!

Some googling and MOS searches revealed that the error was due to corrupted archive log file. Recopying the archive file from primary and restarting the recovery resolved the issue. The fist argument of the ORA-600 is actually the sequence no of the archive it is trying to apply.

Categories: BI & Warehousing

Writing tips

Tue, 2015-05-19 04:14

Tim Hall has written some brilliant posts about getting going with writing (blogs, whitepapers etc). This post is the result of inspiration from there only. Tim says that just get started with whatever Winking smile.

If you are into blogging and no so active or even if you aren’t you may want to take a look at all the posts to get some inspiration to document the knowledge you gain on day to day basis.

Here is an index to all the posts by Tim till now

http://oracle-base.com/blog/2015/05/11/writing-tips-why-should-i-bother/

http://oracle-base.com/blog/2015/05/12/writing-tips-how-do-i-start/

http://oracle-base.com/blog/2015/05/13/writing-tips-writing-style/

http://oracle-base.com/blog/2015/05/14/writing-tips-how-do-i-stay-motivated/

http://oracle-base.com/blog/2015/05/15/writing-tips-dealing-with-comments-and-criticism/

http://oracle-base.com/blog/2015/05/18/writing-tips-should-i-go-back-and-rewrite-revise-remove-old-posts/

http://oracle-base.com/blog/2015/05/19/writing-tips-how-often-should-i-write/

Enjoy !

Categories: BI & Warehousing

Want to learn Exadata ?

Fri, 2015-01-02 03:19

Many people have asked me this question that how they can learn Exadata ? It starts sounding even more difficult as a lot of people don’t have access to Exadata environments. So thought about writing a small post on the same.

It actually is not as difficult as it sounds. There are a lot of really good resources available from where you can learn about Exadata architecture and the things that work differently from any non-Exadata platform. You might be able to do lot more RnD if you have got access to an Exadata environment but don’t worry if you haven’t. Without that also there is a lot that you can explore. So here we go:

  1. I think the best reference that one can start with is Expert Oracle Exadata book by Tanel Poder, Kerry Osborne and Randy Johnson. As a traditional book covers the subject topic by topic from ground up so it makes a fun read. This book is also no different. It will teach you a lot. They are already working on the second edition. (See here).
  2. Next you can jump to whitepapers on Oracle website Exadata page, blog posts (keep an eye on OraNA.info) and whitepapers written by other folks. There is a lot of useful material out there. You just need to Google a bit.
  3. Exadata documentation (not public yet) should be your next stop if you have got access to it. Patch 10386736 on MOS if you have got the access.
  4. Try to attend an Oracle Users Group conference if there is one happening in your area. Most likely someone would be presenting on Exadata so you can use that opportunity to learn about it. Also you will get a chance to ask him questions.
  5. Lastly if you have an Exadata machine available do all the RnD you can.

Happy New Year and Happy Learning !

Categories: BI & Warehousing

VirtualBox and Windows driver verifier

Wed, 2014-12-03 04:34

I was troubleshooting some Windows hangs on my Desktop system running Windows 8 and enabled driver verifier. Today when I tried to start VirtualBox it failed with this error message.

Failed to load VMMR0.r0 (VERR_LDR_MISMATCH_NATIVE)

Most of the online forums were asking to reinstall VirtualBox to fix the issue. But one of the thread mentioned that it was being caused by Windows Driver Verifier. I disabled it, restarted Windows and VirtualBox worked like a charm. Didn’t have time to do more research as i quickly wanted to test something. May be we can skip some particular stuff from Driver Verifier and VirutalBox can then work.

Categories: BI & Warehousing

Oracle GoldenGate 11g Handbook

Thu, 2013-07-18 10:02

Few months ago I contributed a chapter (on Monitoring, Troubleshooting and Performance tuning) to a GoldenGate book on Oracle Press that Robert Freeman was authoring. Thought of posting a small update that the book is now out. My name doesn’t appear on the main page Sad smile but you will see it in the Acknowledgements section Winking smile Below is a screenshot taken from Amazon preview Smile.

You may want to grab a copy if you are using/planning to use Oracle GoldenGate 11g.

Here is the link to the book page on Amazon. It seems the book is not published in India yet but one can order the imported edition on amazon.in

image

Categories: BI & Warehousing

Oracle database 12c

Wed, 2013-06-26 20:58

So there is a new toy in the market for database geeks : Oracle has released database 12c. Every social platform is abuzz with the 12c activity. So thought that I should also complete the ritual Winking smile

In this post Aman has already summed up many important links.

Maria Colgan has posted some useful links here.

And here is a link to a slidedeck about Upgrading and Migrating to 12c.

Happy 12c’ing !

Categories: BI & Warehousing

agent deployment error in EM 12c

Sun, 2013-06-16 12:04

Yesterday I was configuring EM 12c for a Sun Super Cluster system. There were a total of 4 LDOMs where I needed to deploy the agent (Setup –> Add targets –> Add targets manually). Out of these 4 everything went fine for 2 LDOMs but for the other two it failed with an error message. It didn’t give much details on the EM screen but rather gave a message to try to secure/start the agent manually. When I tried to do that manually the secure agent part worked fine but the start agent command failed with the following error message:

oracle@app1:~$emctl start agent
Oracle Enterprise Manager Cloud Control 12c Release 2
Copyright (c) 1996, 2012 Oracle Corporation.  All rights reserved.
Starting agent ………………………………………………………. failed.
HTTP Listener failed at Startup
Possible port conflict on port(3872): Retrying the operation…
Failed to start the agent after 1 attempts.  Please check that the port(3872) is available.

I thought that there was something wrong with the port thing so I cleaned the agent installation, made sure that the port wasn’t being used and did the agent deployment again. This time it again failed with the same message but it reported a different port number ie 1830 agent port no:

oracle@app1:~$emctl start agent
Oracle Enterprise Manager Cloud Control 12c Release 2
Copyright (c) 1996, 2012 Oracle Corporation.  All rights reserved.
Starting agent ……………………………………………. failed.
HTTP Listener failed at Startup
Possible port conflict on port(1830): Retrying the operation…
Failed to start the agent after 1 attempts.  Please check that the port(1830) is available.

Again checked few things but found nothing wrong. All the LDOMs had similar configuration so what worked for the other two should have worked for these two also.

Before starting with the installation I had noted the LDOM hostnames and IPs in a notepad file and had swapped the IPs of two LDOMs (actually these two only Smile with tongue out ). But later on I found that and corrected. While looking at the notepad file it occurred to me that the same stuff could be wrong in /etc/hosts of the server where EM is deployed. Oh boy that is what it was. While making the entries in /etc/hosts of EM server, I copied it from the notepad and the wrong entries got copied. The IPs for these two LDOMs got swapped with each other and that was causing the whole problem.

deinstalled the agent, correct the /etc/hosts and tried to deploy again…all worked well !

Categories: BI & Warehousing