As the name suggests, Disaster Recovery means recovering in case of any disaster. This is a much popular method used for SQL Server database safeguard. By setting up a disaster recovery strategy and its timely execution, users can recover the data lost because of any type of natural or man-made disaster.
In this post, we will discuss some SQL Server Disaster Recovery options. This will help the users in choosing the right Disaster Recovery measures for SQL Server. But they must keep in mind that every organization’s need is different. That is why, the customized Disaster Recovery policy should reflect the requirements of the company.
Best SQL Server Disaster Recovery Options
Here, we will discuss the methods often considered for SQL Server Disaster Recovery by various organizations. We will learn about the approaches in brief and also know their pros and cons.
Backup and Restore
SQL Server offers this feature to its users, which is the most basic method of Disaster recovery. Using various native techniques like T-SQL, PowerShell, or SSMS, full backup of the complete database can be created and saved in a secure location. In case of both data loss and data corruption, users can easily restore the data from the last good backup. While using this feature, database can be compressed and encrypted, as these are supported by SQL Server.
Pros and Cons: The biggest advantage of this method is that the backup can be saved on any location including external media storage devices. There is also no network dependency involved in it. Its demerits are the requirement of manual database restoration and loss of data since last good backup.
Important: Microsoft suggests that you should run backup and restore in a test environment before implementing it on the business environment. Also, do not depend on this method solely in case of business-critical database.
This is another method used for downtime management and disaster recovery. Here, multiple clusters are created out of the group of servers. In case a node crashes or seizes to function, another cluster takes over the operation and automatically restarts the application. Here, it does not require any manual intervention. This method uses SAN and NAS for shared data storage and various network connections and thus removes the single failure point. Through quorum-based approach, node-level fault tolerance is increased. The same approach is used by failover cluster for monitoring cluster health.
Pros and Cons: The best thing about this solution is it gets enabled automatically whenever the primary server is unavailable. But it involves high cost and server location should be the same. On the other hand, Disk array failure is not possible to prohibit in this method. Also, these clusters are not available at database or database object level.
This method got introduced in the Developer and Enterprise editions of SQL Server 2000. In the latest SQL 2017, this is supported by both the Standard and Enterprise editions. The term log shipping means exporting log file of the primary database to another database. In this process, minimum two or more SQL Server instances are involved. Apart from the primary server, other servers are the standby ones. This can be used at the database level only and not at the instance level. Also, automated failover is not available here.
Pros and Cons: With the help of this process, all database objects can be recovered during any disaster. This method also speeds up the processes of log file restoration and data recovery. During the data restoration, the database remains inaccessible. Log shipping is also devoid of granular restoration. Restoration has to be implemented for all the changes done in primary server. Besides, whenever the primary server fails, users need to redirect the applications to the standby server as automated failover is unavailable.
This solution is commonly used for SQL Server Disaster Recovery as well as High Availability . This technique can be implemented of databases with full recovery model. Users can choose from synchronous or asynchronous copy for a single database only. Since no future SQL Server versions (SQL Server 2017 is the last one) will have this feature, Microsoft asked users to go for AlwaysOn Availability Groups or Basic Availability Groups.
Pros and Cons: If you use database mirroring, you are not only become able to protect your database in a better way but also its availability gets higher. Even while upgrading, production database availability gets improved due to database mirroring. The disadvantage of this process is that the mirror database and the main database should be completely identical in every way, including all the objects and logins. Users also need to be careful about the data security as this process involves data transfer between two systems through a network.
In Transactional Replication, data from the primary Server (the publisher) is copied to the secondary Server (the subscriber). This approach can be applied to table level and other object levels. It works best when the database is small and the recovery process requires to be fast. In this way, users can use the subscriber Server if the publisher Server fails after disaster. It is mostly used in server to server environment.
Pros and Cons: In this process, the changes are done in small intervals and users can view the data during the changes are being applied. Transaction replication is slower than the process of log shipping. Replication configurations will be gone once the servers are switched. Once Replication is done, changes in Schema or security will be unavailable to the subscriber. Server switching should be done manually after the occurrence of the disaster.
SQL Recovery As The Ultimate Disaster Recovery Option
If you have lost data due to any disaster even before implementing these options, MDF Recovery tool is there for you. This software can easily recover deleted data from SQL Server database. The tool can also remove high-level corruption issues with Advanced Scan mode. This application cannot be used as the preventive measure against the disasters, but it is helpful after the data got deleted or corrupt or inaccessible.
As every SQL Server should have a customized Disaster Recovery policy in place, we have discussed some of the useful SQL Server Disaster Recovery options here. We presented both the pros and cons of these solutions so that users can choose the ones suitable for their requirement. It is expected that users will get benefited by this write-up.
Author: Andrew Jackson