ActiveCluster provides a powerful solution for SQL Server workloads by enabling synchronous replication across FlashArray instances, ensuring identical volume identities across arrays. This capability supports use cases such as high availability for mission-critical databases and seamless non-disruptive storage migration. SQL Server hosts can be zoned to ActiveCluster on FlashArray or Everpure™ Cloud Dedicated block storage, ensuring uninterrupted access to databases while maximizing data resilience and operational efficiency.
This paper covers a common SQL Server environment consisting of multiple interconnected components, which include the following:
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SQL Server instances running on Windows Server or a supported Linux platform
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2 x FlashArrays used for primary storage protected by ActiveCluster
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Everpure Cloud Dedicated for primary storage of SQL Server instances in Microsoft Azure or Amazon Web Services
Solution Benefits
ActiveCluster offers a range of critical benefits tailored to storage and SQL Server administrators. These features help ensure continuous database availability, simplify management, and reduce operational overhead, making ActiveCluster an ideal solution for both small and medium-sized businesses and enterprise IT environments.
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Synchronous replication for data integrity: SQL Server data is synchronously replicated with ActiveCluster across two FlashArray systems, ensuring data is written to non-volatile RAM on both arrays before acknowledging the write to the host. This helps ensure data consistency and reliability, which are key concerns for database administrators managing mission-critical workloads.
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Active/active architecture for optimized access: With a symmetric active/active configuration in ActiveCluster, SQL Server hosts can read and write to volumes on either array, improving data accessibility and enabling seamless operations across arrays. The ability to manage host-to-array site preferences also provides SQL Server administrators with greater control over data flow, helping ensure optimal performance.
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Transparent failover for uninterrupted operations: ActiveCluster supports automatic, transparent failover between arrays without disrupting SQL Server operations. Administrators can specify failover preferences, and the system will autonomously manage the process, ensuring SQL Server databases remain available even during array or site failures.
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Simplified storage management: SQL Server database administrators benefit from simplified management with the unified ActiveCluster interface. Provisioning storage, creating snapshots, and managing replication are all streamlined, reducing the complexity of maintaining a highly available database environment.
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No additional licensing costs: ActiveCluster requires no additional hardware or software licenses, allowing organizations to maximize their investments in FlashArray systems.
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Integrated cloud-based failover mediation: The integrated Pure1® Cloud Mediator solution automatically manages failovers between arrays, preventing split-brain scenarios and eliminating the need for additional on-premises components. This ensures SQL Server environments maintain high availability without additional infrastructure overhead.
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Support for non-disruptive storage migration: ActiveCluster also supports non-disruptive migration of SQL Server databases across arrays, ensuring that storage upgrades or site changes can occur without impacting database performance or availability. This is particularly beneficial for administrators managing dynamic environments with evolving storage needs.
By addressing the core challenges of SQL Server high availability, ActiveCluster helps storage and database administrators maintain business continuity, reduce downtime, and improve operational efficiency—all without the need for complex infrastructure.
Limitations of ActiveCluster
While ActiveCluster offers robust high availability and synchronous replication for SQL Server environments, there are specific limitations to consider for optimal deployment. These include proximity requirements for latency, architectural design considerations, and dependencies on additional components to enable automatic failover.
The ActiveCluster synchronous replication capability is highly effective for SQL Server environments requiring high availability across storage arrays. However, to ensure optimal performance, it is recommended to maintain latency below five milliseconds, which is typically achievable between data centers located within metro proximity of one another. Distances exceeding this threshold might introduce latency that could impact SQL Server application performance, making ActiveCluster best suited for geographically close data centers.
The ActiveCluster architecture supports active-active replication between two FlashArray systems, facilitating seamless data accessibility and redundancy across a dual-site setup. However, it is designed for a two-site configuration and does not support additional arrays within the same synchronous setup. For SQL Server environments requiring multi-site disaster recovery, other solutions such as ActiveDR™ or asynchronous replication can be used.
To enable automatic failover capabilities, ActiveCluster requires the use of a mediator or witness component, such as the Pure1 Cloud Mediator. This cloud-based solution, or an on-premises mediator, ensures SQL Server environments maintain high availability by managing failover autonomously. Without this component, manual intervention is needed in the event of an array failure, which can impact recovery times in critical scenarios.