Recovery from SQL Server Failures

A major disaster has occurred, and the backup is located offsite or with a cloud service provider. To ensure a smooth recovery, it is essential to have a Database Administrator (DBA) available at all times who has experience in similar situations. What methods can be employed to restore the database system quickly?

From what do you begin?

In order to identify the most essential aspects of your organisation, it is recommended to ask yourself a set of questions that will help you pinpoint those areas at most risk of disruption. These questions should include: what is the maximum data loss that can be tolerated; what is the maximum amount of downtime that can be accepted; and approximately how long will it take to restore operations.

Recovery Point Objective (RPO) and Recovery Time Objective (RTO) are two useful notions for figuring out the answers to such issues (RTO).

The Recovery Point Objective (RPO) determines the amount of time for which healthy data should be retrievable prior to any system failure, in this case a minimum of two minutes.

The Recovery Time Objective (RTO) is the duration of time required to restore operations within the Recovery Point Objective (RPO) that has been set. For example, services can be restored in a maximum of three minutes. It is recommended to assess the current status of database systems before commencing work on a Business Continuity Plan, which should be based on the gathered information.

A variety of power outages

Understanding what sorts of outages your SQL Server might suffer from will help you pick the correct architecture and features to combat them.

In the event of a single server failure due to an operating system crash, patch installation failure, failed RAM/CPU, or disk failure, a High Availability solution should be implemented to ensure the affected data is relocated.

In the event of wide-reaching issues, such as network switch or SAN failure or natural disasters, a Disaster Recovery solution can be implemented to protect data and applications. This may include replicating data and applications to a separate part of the data centre.

Invalidation of databases It is possible that SAN failures, SQL issues, and corruption may occur. Human errors such as dropping the wrong table or database, or updating without a where clause, could lead to such situations. Careful procedures should be followed to resolve such issues, as well as strategies developed to prevent them.


SQL Server can help reduce downtime and enable businesses to make the most of their high availability. In this post, we’ll discuss the capabilities that can help achieve this.

Ensuring regular backups and restores are in place is essential. It is important not to overlook the basics when it comes to data recovery. To ensure your Recovery Point Objective (RPO) and Recovery Time Objective (RTO) are met, it is important to test your backups regularly. Additionally, using differential, transaction log, and filegroup backups can help bring your database online faster than a complete backup alone.

Databases can be replicated in both directions and in a wide range of formats to aid the exchange of data between local and remote locations. It is advisable to only replicate the necessary data, which can be beneficial for smaller datasets and when sending/receiving information between separate sites such as stores, delivery hubs, etc.

Log Shipping is a process wherein transaction logs are automatically backed up and restored to another database, either locally or remotely, allowing for both databases to be in a read-only replica (Standby) state.

FCI (Failover Clustered Instances) provide “Always-ON” capabilities, allowing multiple servers to work together to store data. In the event of a node failure, resources are redistributed among the remaining nodes, which can be located in either the same datacentre or an entirely different facility.

Availability Groups provide an ‘always-on’ function with a collection of SQL servers, each of which holds its own data on separate disks. In the event of an instance failure, only the affected databases need to be moved. You have the option to use an asynchronous or synchronous secondary, read-only replica for backup offload and other requirements, making it ideal for use in time-sensitive scenarios.

Storage replication enables data migration between sites and Storage Area Networks (SANs). This process replicates volumes across servers or clusters and subsequently replicates disk blocks.

To ensure a fast recovery of your infrastructure in the event of a disaster, you can implement virtual machine replication. This consists of copying running virtual machines by taking a snapshot of the entire server.


When I initially discussed the importance of appreciating your database, I highlighted its relevance. The higher the necessity for almost no data loss, the more the investment in SQL features and infrastructure must be to fulfil that requirement. Defining your priorities clearly will enable you to allocate more resources to the areas that will yield the highest return.

You have three primary choices here:

The Enterprise Edition of SQL provides a comprehensive set of features that offer the ability to create sophisticated applications and a reliable, scalable database. I would like to draw attention to the high scalability of I/O operations, online page and file recovery, and the Distributed Availability Groups (enabling cross-domain and network availability).

The Standard Edition of SQL is a reduced version of the full product, containing the majority of the same features as the Enterprise Edition, with some exceptions (including Basic Availability Groups for 2-server clusters, rapid database recovery, and failover cluster instances).

Web and Express are free but severely stripped-down variants.

Get things done

Investing time in designing and implementing effective fixes will be beneficial should your databases experience any issues. Our team of IT experts at Works are among the best in the business and are capable of designing and implementing appropriate methods to protect your organisation from short outages or major catastrophes.

By implementing an effective backup schedule, configuring the necessary parameters such as I/O, the number of files and exploring more complex designs such as availability groups across multiple rooms, domains and data centres, we can ensure that any disruptions to the business are kept to a minimum, allowing us to focus our attention on strategies that will maximise profits.

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