Introduction to Intel Pin

This blogpost is an introduction to Intel’s Pin dynamic instrumentation framework. Pin and the pintools were brought to my attention by Mahmoud Hatem in his blogpost Tracing Memory access of an oracle process: Intel PinTools. The Pin framework provides an API that abstracts instruction-set specifics (on the CPU layer). Because this is a dynamic binary instrumentation tool, it requires no recompiling of source code. This means we can use it with programs like the Oracle (more...)

Redo a blogpost

This blogpost is about the Oracle redo log structures and redo efficiency in modern Oracle databases. Actually, a lot of subtle things changed surrounding redo (starting from Oracle 10 actually) which have gone fairly unnoticed. One thing the changes have gone unnoticed for is the Oracle documentation, the description of redo in it is an accurate description for Oracle 9, not how it is working in Oracle 10 or today in Oracle 12.1.0. (more...)

Smart Scans efficiency chart for Oracle Engineered Systems

If you manage an Oracle Engineered System you may wonder how well your Smart Scans are performing. Are you taking full advantage of Exadata Optimizations? If so, how do you measure them?

Uwe Hesse explains well some important statistics on Exadata. For some time now, eDB360 includes a report on Smart Scan efficiency, which is nothing but a Google Chart on top of relevant statistics.

Sample chart below is from a data warehouse DW application. It (more...)

DOAG Konferenz 2016

| Nov 5, 2016


Noch eine Woche und ein paar Tage dann startet die DOAG Konferenz 2016.

Es warten viele Interessante Themen rund um das Thema Oracle.

Einfach mal über den Link ins Vortragsprogramm schauen.



Exadata memory configuration

Read this post if your Exadata compute nodes have 512/768GB of RAM or you plan to upgrade to the same.

There has been a lot of information about hugepages and I wouldn’t go into too much details. For efficiency, the (x86) CPU allocates RAM by chunks (pages) of 4K bytes and those pages can be swapped to disk. For example, if your SGA allocates 32GB this will take 8388608 pages and given that Page Table (more...)

OTN Appreciation Day:

In the wake of the great hospitality shown by the OTN crew at Open World, Tim Hall thought that getting the community together for a series of “OTN appreciation” blogs would be a good way to show our thanks back.

Thinking about tools provided by Oracle that make my life easier, my mind went to  This tool helps automate many of the tedious tasks that must be performed when performing an OS update on an Exadata compute (more...)

How to enable Exadata Write-Back Flash Cache

Yes, this is well-known and the process has been described in Exadata Write-Back Flash Cache – FAQ (Doc ID 1500257.1) but what the note fails to make clear is that you do NOT have to restart cell services anymore hence resync the griddisks!

I had to enable the WBFC many times before and every time I’d restart the cell services, as note suggests. Well, this is not required anymore, starting with 11.2.3. (more...)

Extending an Exadata Eighth Rack to a Quarter Rack

In the past year I’ve done a lot of Exadata deployments and probably half of them were eighth racks. It’s one of those temporary things – let’s do it now but we’ll change it later. It’s the same with the upgrades – I’ve never seen anyone doing an upgrade from an eighth rack to a quarter. However, a month ago one of our customers asked me to upgrade their three X5-2 HC 4TB units from (more...), failed and IB listener

So this customer has an Exadata quarter rack and they have an IB listener configured on both DB nodes (for DB connections from a multi-racked Exalogic system). We were adding a new DB node to this rack. So just followed the standard procedure of creating users, directories etc on the new node, setting up ssh equivalence and running All went fine but failed. Little looking into the logs revealed that it (more...)

OEDA–Things to keep an eye on

So if you are filling an OEDA for Exadata deployment there are few things you should take care of. Most of the screens are self explanatory but there are some bits where one should focus little more. I am running the Aug version of it and the screenshots below are from that version.

  1. On the Define customer networks screen, the client network is the actual network where your data is going to flow. So typically (more...)

How to resolve missing dependency on exadata-sun-computenode-minimum

I’ve been really busy last few months – except spending a lot of time on M25 I’ve been doing a lot of Exadata installations and consolidations. I haven’t posted for some time now but the good news is that I got many drafts and presentations ideas.

This is a quick post about an issue I had recently. I had to integrate AD authentication over Kerberos on the compute nodes (blog post to follow) but had (more...)

SCAN Listener Crash After Applying July 2016 PSU

I ran in to a small issue while applying the July 2016 quarterly patch to a couple of Exadata racks last week.  The systems were running GI, previously with the January 2016 PSU.  The patches applied successfully, and we were beginning the process of running the post-patch scripts on the databases in the cluster.  This process involves manually starting the database in upgrade mode, and we saw a message in SQL*Plus that the (more...)

Redirecting ILOM Console Via SSH Tunneling With Putty

While preparing for a virtualized Exalytics upgrade, I was testing the various connection methods that would be needed.  Last on the list was to validate that I could connect to the ILOM’s web interface, launch the java console, and mount an ISO file from my laptop to the machine.   This is necessary because the Oracle VM server upgrade for a virtualized Exalytics requires you to boot from a specific ISO file in order to patch (more...)

Notes on vendor lock-in

Vendor lock-in is an important subject. Everybody knows that. But few of us realize just how complicated the subject is, nor how riddled it is with paradoxes. Truth be told, I wasn’t fully aware either. But when I set out to write this post, I found that it just kept growing longer.

1. The most basic form of lock-in is:

  • You do application development for a target set of platform technologies.
  • Your applications can’t run (more...)

How To Configure Exadata Database Machine in Enterprise Manager Cloud Control 13c (OEM13c)

I have followed the steps in Oracle Documentation link: to configure Exadata Database Machine in OEM13c. If you want to configure your Exadata in OEM13c you have to follow the above mentioned link. In this post I will share the mandatory steps for configuration, and some of the issues which I faced while configuring the Exadata…

How To Avoid Exadata Cell Node Reboot While Modifying NTP Service

Recently, we had a hardware failure on our NTP server which caused its crash. Due to this, the ntpd daemon on compute nodes and cell nodes went offline. After fixing the hardware issue on NTP server, starting ntpd service using "service ntpd start" on compute nodes was successful but when I started the ntp service…

ORA-56841: Master Diskmon cannot connect to a CELL

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 (more...)

Is Your Data Center Ready For Exadata Machines!!

Before opting to procure Exadata machines, the first thing you need to check is the readiness of your data center to hold these machines. Exadata's dimensions are similar to other normal racks i.e a 42U rack. The complete details for X5-2 physical site requirements can be found HERE. This is very important step as, for some data…

Exadata X6-2 Launched

5th April 2016, Oracle announced arrival of Exadata X6-2. Overview of all its capabilities can be found HERE. Check DataSheet for list of hardware components and capacity of each X6-2 rack. Sometimes, Oracle changes hardware specifications for its racks e.g X5-2 was released with 4TB HDD initially, but after few months the datasheet was modified and…

Planning Database Hardware Upgrade !!! Consider Oracle Exadata

Upgrading database hardware in an organization is always a cumbersome process. The most time consuming step is, planing for the upgrade, which mainly includes choosing right hardware for your Oracle databases. After deciding on the hardware type for your databases, rest will be taken care by technical teams involved. I will be discussing, how I…