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Using Datapump from SQLDeveloper

One problem that we all have is with exporting/importing between different versions of the datapump client. The following error is not uncommon

UDI-00018: Data Pump client is incompatible with database version

Permissions problem with and tnsnames.ora

There is a Bug documented in MoS regarding the setting of permissions by the script (which calls  This causes the ownership of grid home to be owned by root and permissions given to oinstall group

app/gridsoft/ $ls -ld

drwxr-x---  65 root       oinstall      2048 Feb 27  2012 . 

Balancing ASM disks in one command – the benefits

As a response to my previous post about adding and dropping ASM disks with one command Emre Baransel asked a question as to whether it was more efficient or not to do it as one or two commands. It was easier to add  a second post complete with screen shots rather than just a simple reply.

My test system was a 3.5Tb database spread across 10 512Gb luns.

The first choice was to add and drop in one command

ASM – Adding and dropping disks in one command

One of the possibilities within ASM that is not widely documented is the opportunity to add disks, drop disks and set the rebalance power all in one command.

One might wonder when you might be both adding and dropping disks simultaneously from the same disk group. Recently we have been migrating to a new storage array and this command comes in very useful in that situation

Test Case for 11gR2 Role Separation issue on HP-UX – help wanted

On any HPUX (11:31) system where grid infrastructure has been applied with 2 software owners – in our case grid and oracle  – oracle’s best practise for GI implementations – RAC or standalone systems.

 The standard  unix account we are using  is , testuser (although in this case he is in the DBA group).

 This user is a member of the following groups :

Huge asm_rbal_trace file with text UNINDENT OF DISK

You may notice a large and growing trace file in diag dest which contains numerous lines starting with the phrase “NOTE: Unident of disk ” followed by a disk path.

Curing unevenly balanced ASM diskgroups to reduce poor file distribution

Back in Nov 2011 I posted a question on the Oracle-L mailing group about my perception that ASM disk rebalances seemed to be required on DATA diskgroups in ASM  (never FRA, presumably because the FRA had lots of similar sized objects (flashlogs archivelogs  etc)) and even after rebalancing there seemed to be a permanent imbalance between disks of the same size. I was querying the effectiveness of the rebalancing operation.

Excellent Optimizer Statistics articles

For anybody who is interested in reading about optimizer statistics and gaining a clear understanding on what they can do and how they can be managed then I suggest reading the following two white papers

Part 1 – Understanding Optimizer Statistics

Part 2 – Best Practises for Gathering Optimizer Statistics

Interview questions – one approach

In my last post I talked about doing a lot of interview questions lately. I have been thinking of changing my standard set of questions anyway so I thought it would be a good idea to write about the questions I have been asking and the responses I get.

Alter system v Alter database – which to guess at

I have been doing a lot of interviewing recently and I have a set of questions which are quite generic but I like to use them to lead into areas where I can probe a bit deeper if the interviewee allows me to get  that far by answering the question correctly in the first place.

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