ALERT

[FREE DEMO] Deploy Your Enterprise Cloud in Minutes

Log Shipping

Definition - What does Log Shipping mean?

Log shipping is a feature of Microsoft’s SQL Server in which recorded changes to a database (logs) are automatically transferred to a replica database set up on a standby server. It is a powerful and useful tool for increasing database availability by maintaining a second warm database that can fill in reasonably quickly for a suddenly unavailable primary database.

Note that the ability to move database changes in real time from one database to another is not unique to SQL Server. Log shipping is simply Microsoft’s implementation of the concept.

Techopedia explains Log Shipping

Log shipping is slightly different from database mirroring. It is an asynchronous movement of changes from one server to the other and can occur with a primary database’s changes being transferred to several standby databases. Also, in case of failure of the primary database, the failover to the standby database must be done manually.

Mirroring, on the other hand, is a real-time synchronization of changes, just as the name suggests - your image in the mirror raises its hand when you raise yours, and not a few minutes later! In mirroring, database failover is automated, unlike in log shipping.

So one may ask why log shipping is even necessary if mirroring is available. The short answer is cost. Mirroring can be quite expensive, since it usually needs a third server in addition to the primary and standby servers, as well as high-speed data links between the servers to ensure real-time copying of logs. Log shipping offers a sort of compromise between the high cost and automated redundancy, albeit with the following caveats:

  • Database failover is not automatic
  • The standby database is unavailable for editing.
  • There is some downtime while database administrators change over operations to the new server.
  • There is still the risk of some data loss if the last few minutes of data from the primary server were not copied through before becoming unavailable.

Log shipping is ideal for situations in which it is not absolutely critical to maintain 100% uptime.

Techopedia Deals

Connect with us

Techopedia on Linkedin
Techopedia on Linkedin
Tweat cdn.techopedia.com
"Techopedia" on Twitter


'@Techopedia'
Sign up for Techopedia's Free Newsletter!

Email Newsletter

Join thousands of others with our weekly newsletter

Resources
The 4th Era of IT Infrastructure: Superconverged Systems
The 4th Era of IT Infrastructure: Superconverged Systems:
Learn the benefits and limitations of the 3 generations of IT infrastructure – siloed, converged and hyperconverged – and discover how the 4th...
Approaches and Benefits of Network Virtualization
Approaches and Benefits of Network Virtualization:
Businesses today aspire to achieve a software-defined datacenter (SDDC) to enhance business agility and reduce operational complexity. However, the...
Free E-Book: Public Cloud Guide
Free E-Book: Public Cloud Guide:
This white paper is for leaders of Operations, Engineering, or Infrastructure teams who are creating or executing an IT roadmap.
Free Tool: Virtual Health Monitor
Free Tool: Virtual Health Monitor:
Virtual Health Monitor is a free virtualization monitoring and reporting tool for VMware, Hyper-V, RHEV, and XenServer environments.
Free 30 Day Trial – Turbonomic
Free 30 Day Trial – Turbonomic:
Turbonomic delivers an autonomic platform where virtual and cloud environments self-manage in real-time to assure application performance.