DBA Responsibilities

• Installing and upgrading the database server and application tools.
• Allocating system storage and planning future storage requirements for the database system.
• Modifying the database structure, as necessary, from information given by application developers.
• Enrolling users and maintaining system security.
• Ensuring compliance with database vendor license agreement.
• Controlling and monitoring user access to the database.
• Monitoring and optimizing the performance of the database.
• Planning for backup and recovery of database information.
• Maintaining archived data.
• Backing up and restoring databases.
• Contacting database vendor for technical support.
• Generating various reports by querying from database as per need.

Oracle DBA Levels:-

L1(Level 1)
Key skills required are:- Communication, Customer facing skills.
Support:-

1. logs, categorizes, prioritizes, tracks, and routes 
2. incidents reported by users or 
3. alarms raised by monitoring tools. 

Task:-L1 is intended to be the first to acknowledge an incident. L1 support tracks tickets until successfully resolved. L1 engineers can implement basic, documented break-fix tasks along the lines of following a cookbook recipe.
Escalation:-L1 personnel will typically escalate to an L2 resource and follow documented escalation procedures.

L2(Level 2)
Key skills required are:- Product Knowledge, Communication, Customer facing skills and Domain Knowledge.
Support:- tries to reproduce the problem in an environment similar to where the problem was reported and does the initial triage of the issue and provide as much detail to the 3rd Level support, if they can't resolve the issue.
Task:- Some of the common fixes done by Second Level Support are configuration changes, data back-load, data correction, app restart etc. L2 technicians follow documented processes and workflows provided by Clients or higher level support representatives, vendors, product management, etc.
Escalation:-They are expected to escalate to the L3’s when documentation is insufficient to complete the tasks or do not solve the incident

L3(Level 3)
Support:- fix an issue by code changes and participates in the build and release management activities.
Task:-L3 engineers participate in management, prioritization, minor enhancements, break fix activities, problem management, stability analysis, etc.
Escalation:-If a fix involves a major enhancement or a development, then the problem is transferred to engineering or development teams, Level 4.

L4(Level 4)
Support:- Refers to product or vendor support and often involves vendor product architects, engineers, software developers, hardware designers and the like.