Monthly Archives: February 2009

ORA-00845 Memory_Target Not supported on this system

I was working on testing some 11g streams configurations today. I needed to startup 3 databases instances on the same server. I was using AMM (Automatic memory management). When i was trying to startup the 3rd database, i kept getting the error message “ORA-00845: MEMORY_TARGET not supported on this system”. I also had error messages in the alert log.

This is because, the space allocated for /dev/shm is not sufficient to allocate the SGA+PGA’s for all the 3 database instances (When using the initialization parameter memory_target). The space allocated needs to be >= the total SGA+PGA size of all the 3 instances together.

You can increase the space allocated using the command  “mount -t tmpfs shmfs -o size=2000m /dev/shm” ( I had 3 instances 600mb each SGA+PGA). You can persist this allocation across reboots by adding it to the /etc/fstab.

Xsane and Ghostscript

Today, i ended up having to scan some receipts in, to send my expense reports. I had never tried using printer-scanners with ubuntu ever. But i was pleasantly surprised, by how well, Xsane the linux program for acquiring images with scanners, worked. It worked seamlessly with my HP-Photosmart-C4400 series printer-scanner (Dint have to install any drivers or anything of that sort). You can choose between saving the image as a jpeg or a pdf file.

Once I scanned the images, i ended up with two distinct pdf documents (1 page each), which i had to then combine before i submitted my expense report. I used  ghostscript, with the following switches, to combine these two files  into a single file.

gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOUTPUTFILE=merged.pdf Tempout-0001.pdf Tempout-0003.pdf

Tempout-0001.pdf and Tempout-0003.pdf are the files I am merging into merged.pdf.

Simple Rails Program

Thought building applications  using Microsoft Access was easy ? try building one in Rails, it is Easy…

Install and configure ruby and rails as described in my earlier post.

First create a directory to hold your Rails code. Let us say /u01/ror

cd /u01/ror

Issue the following command to create the necessary rails directory structure

rails test

cd to the config directory

cd test/config

Edit the database Connection properties file

vi database.yml

Modify the details for the development environment as follows (You can remove test and production). Make sure you use oracle_enhanced as the adapter, and not just oracle.

adapter: oracle_enhanced
database: RK01
username: scott
password: tige

cd /u01/ror

Create the Model/View and Controller

script/generate scaffold Customer name:string contact:string phone:string email:string

Create the table named Customers in the Oracle database

rake db:migrate

Start the web server

ruby script/server

Then you can access the application you just created by going to your browser and putting in the URL http://localhost:3000/customers.

This application can now view/add/modify/delete customer information

“That was easy”

Simply Rails 2” by patrick lenz is a great book for Rails beginners and includes Rails 2 information.