Open a terminal window and execute the following command:

dbca

At the Welcome window, click Next.

At the Operations window, make sure Create a Database is selected and click Next.

At the Database Templates window, select General Purpose and click Next.

At the Database Identification window, enter asm.oracle.com for the Global Database Name and asm for the SID and click Next.

At the Management Options window, accept the defaults and click Next.

At the Database Credentials window, enter a Password and Confirm Password and click Next.

At the Storage Options window, select Automatic Storage Management (ASM) and click Next.

At the Create ASM Instance window, click ASM Parameters.

Enter /u02/asmdisks/* (or the path where your disks are located) in the asm_diskstring value field and click Close.

Enter a SYS Password and Confirm SYS Password and click Next.

Click OK to create and start the ASM instance.

Now you will create your ASM Disk Group. At the ASM Disk Group window, click Create New.

Enter DGROUP1 in the Disk Group Name field. A list od Member Disks should appear. Check the checkbox next to Disk Path to select all the disks. If a list of Member Disks does not appear,

Select the Disk Group you just created and click Next.

Make sure Use Oracle-Managed Files is selected and +DGROUP1 is entered in the Database Area and click Next.

Deselect Specify Flash Recovery Area and click Next.

Accept the defaults. Click Next.

Accept the defaults. Click Next.

Accept the defaults. Click Next.

Click Finish.

Click OK.

The progress window appears. The database is being created.

The ASM database was created successfully. Note the Enterprise Manager URL. Click Exit.

Start Oracle Enterprise Manager (Desktop icon) by entering the URL http://<your hostname>:5501/em/ and enter sys/<password> as SYSDBA. Then click Login.

At the Licensing window, scroll down to the bottom and click I Agree.

Click the instance name that ends with +ASM1.

See the pie chart on the right. Click the piece of the pie belonging to ASM DGROUP1 Disk Group.

Login to the ASM instance using userid sys/<password> as SYSDBA. You need to login to the ASM instance because you've selected a disk group, and disk groups are managed in the ASM instance.

View the disks in the disk group. Note that the data is evenly spread across the four disks.

On the page from the last step of the previous topic (the disk listing for the disk group) select the disk DGROUP1_0002 and then click Delete.

Confirm the delete. Click Yes.

Click the Performance tab.

Set the Refresh rate (see the top right of the page) to 15 seconds and observe the graph changes after refreshes.

After the graph changes settle (this may take several minutes) click the General link in the upper left of the page to go back to the general disk group information page.

Note that the DGROUP1_0002 disk no longer appears in the list. If it is still there, it should have a "State" of "DROPPING". Refresh the page until it is removed from the list.

Note that each of the 3 disks now has a greater percentage used. That is because the data from the dropped disk has been rebalanced onto the remaining three disks.

Before actually adding the disk back to the disk group, generate some test data for later use. Alt-tab to a terminal session and type the commands below:

cd /home/oracle/wkdir

./pop_t1.sh

Note the "Elapsed" timing value for the query at the end. You will compare this to later query timings.

Keep this window open, sitting at that directory.

Go back to the Enterprise Manager page, and click Add Disks.

On the left, select the disk that was removed previously, whose path is "/u02/asmdisks/disk4". (Note that it is the only disk with a "Header Status" of "FORMER". In the "ASM Disk Name" column, enter DGROUP1_0002. Leave the other column values as the default.

Do not click on the OK button yet.

Alt-tab back to the terminal window, and run the command below. As soon as you press <enter> to start this script.

./poll_timing.sh

Immediately alt-tab back to the Enterprise Manager page and click on the OK button.

Switch back to the Enterprise Manager window. Click the browser's Reload button, observing the change in the bar graph for the "Used" column, for each disk, especially noting the growth in the value for the disk just added.

Click Reload again.

Alt-tab back to the terminal window, and scroll through the timings that were output for the same query being run while the data was being rebalanced. Note the change in times for each run. Press ctrl-c to cancel the script when done.