Creating DCLI Group Files in Oracle Exadata

 Creating DCLI Group Files in Oracle Exadata

Oracle Exadata Administration Series

Managing multiple database and storage servers individually can be time-consuming. Oracle Exadata provides DCLI (Distributed Command Line Interface), which allows administrators to execute commands across multiple nodes simultaneously. To simplify administration, Exadata uses group files that contain lists of target servers.

In this article, we’ll learn how to create and use the most common Exadata group files: dbs_group, cell_group, and all_group.

What are Exadata Group Files?

Group files are plain text files that contain hostnames of Exadata servers. These files are used with DCLI commands to execute operations on multiple nodes at once.

Common group files include:

Group File	Purpose
dbs_group	Contains all Database Servers
cell_group	Contains all Storage Servers (Cell Nodes)
all_group	Contains both Database and Storage Servers

Exadata Environment Example

Let’s assume our Exadata rack contains:

Database Servers

ex01dbadm01.gs.local

ex01dbadm02.gs.local

Storage Servers (Cell Nodes)

ex01celadm01.gs.local

ex01celadm02.gs.local

ex01celadm03.gs.local

Step 1: Create dbs_group

The dbs_group file contains all database servers.

vi ~/dbs_group

Add the following entries:

ex01dbadm01.gs.local

ex01dbadm02.gs.local

Verify:

cat ~/dbs_group

Output:

ex01dbadm01.gs.local

ex01dbadm02.gs.local

Step 2: Create cell_group

The cell_group file contains all storage servers.

vi ~/cell_group

Add:

ex01celadm01.gs.local

ex01celadm02.gs.local

ex01celadm03.gs.local

Verify:

cat ~/cell_group

Output:

ex01celadm01.gs.local

ex01celadm02.gs.local

ex01celadm03.gs.local

Step 3: Create all_group

The all_group file contains both database and storage servers.

vi ~/all_group

Add:

ex01dbadm01.gs.local

ex01dbadm02.gs.local

ex01celadm01.gs.local

ex01celadm02.gs.local

ex01celadm03.gs.local

Verify:

cat ~/all_group

Output:

ex01dbadm01.gs.local

ex01dbadm02.gs.local

ex01celadm01.gs.local

ex01celadm02.gs.local

ex01celadm03.gs.local

Quick Creation Using Linux Commands

Instead of manually editing files, you can create them using echo commands.

Create dbs_group

echo -e "ex01dbadm01.gs.local\nex01dbadm02.gs.local" > ~/dbs_group

Create cell_group

echo -e "ex01celadm01.gs.local\nex01celadm02.gs.local\nex01celadm03.gs.local" > ~/cell_group

Create all_group

cat ~/dbs_group ~/cell_group > ~/all_group

Step 4: Validate SSH Equivalence

Before using DCLI, passwordless SSH must be configured.

Test connectivity:

ssh ex01dbadm02 hostname

ssh ex01celadm01 hostname

If no password prompt appears, SSH equivalence is configured correctly.

Step 5: Using Group Files with DCLI

Execute Command on Database Nodes

dcli -g ~/dbs_group -l root "hostname"

Sample Output:

ex01dbadm01 : ex01dbadm01

ex01dbadm02 : ex01dbadm02

Execute Command on Cell Nodes

dcli -g ~/cell_group -l root "cellcli -e list cell"

Execute Command on All Nodes

dcli -g ~/all_group -l root "uptime"

Common DBA Use Cases

Exadata administrators frequently use group files for:

Health Checks

dcli -g ~/all_group -l root "uptime"

Verify Disk Usage

dcli -g ~/all_group -l root "df -h"

Check Running Processes

dcli -g ~/all_group -l root "ps -ef | grep oracle"

Exachk Execution

dcli -g ~/all_group -l root "/opt/oracle.SupportTools/exachk/exachk"

Patching Activities

dcli -g ~/all_group -l root "imageinfo"

Best Practices

✅ Maintain separate group files for Database and Storage servers.

✅ Keep hostnames consistent with DNS or /etc/hosts.

✅ Validate SSH equivalence after adding new nodes.

✅ Use meaningful group names in larger Exadata environments.

✅ Store group files in the Oracle user’s home directory for easier administration.

Conclusion

Group files are a simple but powerful feature in Oracle Exadata administration. By organizing servers into logical groups such as dbs_group, cell_group, and all_group, DBAs can efficiently execute commands, perform health checks, automate maintenance tasks, and manage Exadata infrastructure at scale.

A properly configured DCLI environment combined with group files significantly reduces administrative effort and improves operational efficiency across the Exadata platform.

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