Continuous access to data is crucial for maintaining uninterrupted operations in working environments. Disruptions, even brief ones, can lead to financial loss, reputational harm, and a decline in customer trust. A high availability strategy is therefore critical. The Global Active Device (GAD) addresses this need by providing a robust solution for uninterrupted data availability and business continuity during disruptions or disasters.
Table of Contents
What is a Global Active Device?
- The “Global Active Device” is a technology developed by Hitachi Vinterra. It is a data mirroring feature that creates high availability. Moreover, a GAD enables two different data storage arrays to simultaneously manage, read, and write requests for the same set of data volumes in real-time.
- Unlike traditional setups with a primary site and passive backup, GAD uses two fully operational locations that are both active at all times.
- If one location encounters an issue, the other immediately takes over, ensuring uninterrupted service. Data is continuously and automatically synchronized between both sites, so applications remain operational without disruption.
- Seamless synchronization between the two sites creates a single logical storage pool that is highly available and resilient. This active-active configuration minimizes the risk of failure and delivers exceptional data availability and performance for critical applications.
Core principle of Global Active Device (GAD)
The core principle behind GAD is to present a virtual volume to application servers. This virtual volume is a mirrored pair of physical volumes (LUNs) spread across two storage arrays in different data centers. The technology then ensures that all writes to this virtual volume are synchronously replicated to both physical volumes, guaranteeing that the data is identical at both sites at all times.
GAD (Global Active Device) Approach to Disaster Recovery
The GAD model offers a significant advancement in disaster recovery by moving beyond traditional active-passive configurations to provide continuous availability.
Downtime
When the disaster strikes the primary site, administrators must perform a manual or semi-automated failover to the standby site. Global Active Device (GAD), with its active design, completely bypasses this downtime, providing a continuous operational model.
Data Loss
Traditional disaster recovery methods may result in data loss because they do not always replicate data immediately. In contrast, GAD’s synchronous replication ensures zero data loss, making it an ideal solution for industries such as healthcare and manufacturing that require continuous data protection.
How does the Global Active Device (GAD) work?
The unparalleled and unmatched data availability offered by GAD is the result of several independent technical components working in harmony. The primary goal is to achieve complete data at both sites, ensuring data consistency and preventing the devastating scenario known as “split-brain,” which can occur when two separate sites both believe they are the sole “active” site, leading to data corruption.
Active-Active Architecture
Both storage systems are fully operational and can simultaneously process and write requests for the same data. This eliminates reliance on an inactive backup and ensures continuous protection at both sites.
Synchronous Replication and Quorum Disk
Replication refers to mirroring data so that any information written to one site is immediately copied to the other. This real-time process ensures data remains identical at both locations, achieving a Zero Recovery Point Objective (RPO).
Utilization of Quorum Disk
To prevent the split-brain scenario, Global Active Device utilizes the quorum disk as a third site. This is a small, independent shared disk or a cloud-based quorum service that functions as a tie-breaker. When the two main data centers fail to communicate, the sites cannot determine which one is still operational. They both strive to establish dominance in their roles. The quorum disk resolves this conflict by providing a “vote.” The site that can successfully communicate with and acquire the quorum disk “wins” the vote and stays active, continuing to handle application input and output functions. The other site is then prevented from writing to the shared data, avoiding any data inconsistency or corruption.
Communication Restoration
When communication is restored, the active site synchronizes all updates with the other site, ensuring no data is lost and both sites resume coordinated operation.
Automated Failover and non-disruptive migration
- If one site fails during data transfer due to any technical error, the system automatically redirects all activity to the working site. This immediate handover prevents any service interruption, guaranteeing a Zero Recovery Time Objective (RTO).
- By connecting two active sites, Global Active Device creates a unified storage pool that eliminates single points of failure and supports continuous operations during outages.
- This architecture also enables non-disruptive migration, allowing administrators to move applications between sites or data centers without downtime.
- When server workloads are migrated, applications continue running without interruption, using up-to-date data from the new location.
Conclusion
The Global Active Device has established itself as a crucial component of modern high availability and business continuity strategies. By ensuring zero data loss and zero downtime, GAD technology empowers the most modern organizations to trust their critical data protection and guarantee continuous operations.
FAQs
GAD stands for Global Active Device, a data mirroring and virtualization technology that enables two separate storage systems in different locations to operate simultaneously.
GAD utilizes a third component, known as the quorum disk, to prevent split-brain scenarios. In a split-brain scenario, a communication failure between the two main sites causes both to mistakenly believe that they are only one. A quorum disk acting as a tiebreaker grants control to only one site, which prevents data corruption.
The two main benefits are:
Zero Recovery Point Objective (RPO)
Global Active Device’s synchronous replication ensures that no data is ever lost, because even a small amount of information is mirrored.
Zero Recovery Time Objective (RTO)
At the time of failure, the system automatically fails over, with no downtime for applications or even users.
Global Active Device is particularly suitable and critical for industries such as healthcare, finance, and e-commerce. Moreover, any business where downtime and data loss would result in severe financial or reputational damage, GAD acts like a hero and an absolute game-changer.
