In SQL Server, what is Log Shipping and what is its primary purpose?

Introduction / Context:
High availability and disaster recovery are important topics in SQL Server administration. One traditional mechanism for providing a warm standby database is Log Shipping. Understanding what Log Shipping does, and how it differs from other features, is essential for certification exams and real world deployments. This question asks you to identify the correct description of Log Shipping.

Given Data / Assumptions:

• The environment is Microsoft SQL Server.
• There is a primary production database and at least one secondary or standby database.
• Transaction log backups are available.
• The options mention compression, email, replication, full database copies, and shipping of graphical reports.

Concept / Approach:
Log Shipping is a technique in which transaction log backups from a primary database are taken periodically, copied to a secondary server, and restored there in sequence. This keeps the secondary database nearly up to date with the primary, subject to a delay equal to the backup and copy interval. The main goal is to provide a standby database that can be brought online in case of primary failure or used for read only reporting, depending on configuration.

Step-by-Step Solution:
Step 1: Recall that transaction logs record every change made to a database. Step 2: Understand that in Log Shipping, SQL Server Agent jobs are usually configured to back up the transaction log from the primary database at regular intervals. Step 3: The backup files are then copied automatically to the secondary server and restored there in order, often with the database left in a standby or no recovery state. Step 4: Compare this procedure with each option. Option b matches exactly: it mentions automatic backup, copy, and restore of transaction logs on a secondary standby server. Step 5: Confirm that features such as compression, email alerts, and full replication of entire databases in real time are not the core definition of Log Shipping.

Verification / Alternative check:
In a typical Log Shipping configuration, you can observe three jobs: backup on the primary, copy on the secondary, and restore on the secondary. If you monitor the secondary database, you see that it advances in time as new transaction log backups arrive and are restored. This clearly supports the description in option b and distinguishes it from compression only or simple reporting tasks.

Why Other Options Are Wrong:
A feature that compresses log files to reduce disk usage without any standby server ignores the standby component and is not Log Shipping. A method of sending error logs to developers by email after every failure describes alerting, not log shipping. A form of replication that copies the entire database over the network every time a change occurs sounds more like transactional replication or mirroring, not the scheduled backup based process used in Log Shipping. A reporting tool that ships graphical dashboards to client applications is unrelated to transaction logs.

Common Pitfalls:
Students often confuse Log Shipping with other high availability features such as database mirroring, Always On availability groups, or replication. The key distinguishing feature of Log Shipping is its dependence on transaction log backups and scheduled copy and restore operations, rather than continuous streaming of log records. It is relatively simple and reliable, but the secondary is typically behind the primary by some delay.

Final Answer:
Log Shipping is a process that automatically backs up transaction logs from a primary database and copies and restores them on a secondary standby server.