--- canonical: https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-high-availability-software-synchronous-replication-failover/ --- The Simplest Linux High Availability: 2-Node Synchronous Replication & Failover - SafeKit HA [![Evidian Logo](/wp-content/uploads/2026/01/eviden-logo-black-265-54.png)](https://eviden.com) * [SafeKit](/products/high-availability-software-for-application-clustering/) + - * SafeKit --- * [Home SafeKit](https://safekit.evidian.com/) * [Elevator pitch](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-software-ha-cluster-windows-linux/) * [Customer use cases](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-use-cases) - * Use cases --- * [Best/Worst Use Cases](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/best-worst-use-cases-high-availability/) * [OEM use case for a software publisher](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/application-clustering-software/) * [Distributed Enterprise use case](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/business-continuity-software/) * [Remote sites and disaster recovery use case](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/business-continuity-and-disaster-recovery-software/) - * High Availability in Physical Security Market --- * [Physical Security Software](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/physical-security-software-redundancy/) * [Video Management Software (VMS)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/video-management-software-vms-redundancy/) * [Electronic Access Control Software (EACS)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/electronic-access-control-software-eacs-redundancy/) * [Building Management System Software (BMS)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/building-management-system-software-bms-redundancy/) * [SCADA Software](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/scada-software-redundancy-high-availability/) * [Solutions](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/cluster-configuration/) + - * New application (real-time replication and failover) --- * [Windows (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/windows-high-availability-software-synchronous-replication-failover/) * [Linux (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-high-availability-software-synchronous-replication-failover/) * New application (network load balancing and failover) --- * [Windows (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/windows-load-balancing-failover/) * [Linux (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-load-balancing-failover/) - * Full VM or container real-time replication and failover --- * [Hyper-V (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/hyper-v-replication-automatic-failover-load-balancing/) * [KVM (kvm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-kvm-high-availability-replication-automatic-failover-load-balancing/) * [Docker (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/docker-container-high-availability-cluster-synchronous-replication-failover/) * [Podman (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/podman-the-simplest-high-availability-cluster-between-two-redundant-servers/) * [Kubernetes (k3s.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/kubernetes-k3s-the-simplest-high-availability-cluster-with-synchronous-replication-and-failover-between-two-redundant-servers/) - * Database (real-time replication and failover) --- * [Microsoft SQL Server (sqlserver.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/sql-server-high-availability-synchronous-replication-failover/) * [PostgreSQL (postgresql.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/postgresql-high-availability-synchronous-replication-failover/) * [Oracle (oracle.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/oracle-high-availability-synchronous-replication-failover/) * [MySQL (mysql.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/mysql-high-availability-synchronous-replication-failover/) * [MariaDB (mysql.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/mariadb-simplest-high-availability-cluster-synchronous-replication-failover-redundant-servers/) * [Firebird (firebird.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/firebird-high-availability-synchronous-replication-failover/) * Web (network load balancing and failover) --- * [Apache (apache\_farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/apache-load-balancing-failover-2/) * [Microsoft IIS (iis\_farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/iis-load-balancing-failover/) * [NGINX (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/nginx-the-simplest-load-balancing-cluster-with-failover/) - * Amazon AWS --- * [AWS (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/aws-high-availability-cluster-synchronous-replication-failover/) * [AWS (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/aws-load-balancing-cluster-failover/) * Google GCP --- * [GCP (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/gcp-high-availability-cluster-synchronous-replication-failover/) * [GCP (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/gcp-load-balancing-cluster-failover/) * Microsoft Azure --- * [Azure (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/azure-high-availability-cluster-synchronous-replication-failover/) * [Azure (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/azure-load-balancing-cluster-failover/) * Other clouds --- * [All cloud solutions](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/cluster-in-cloud-computing-generic-solution-amazon-aws-microsoft-azure-google-gcp-other-clouds/) * [Cloud (mirror.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/cloud-high-availability-cluster-synchronous-replication-failover/) * [Cloud (farm.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/cloud-load-balancing-cluster-failover/) - * Physical security (real-time replication and failover) --- * [Milestone XProtect (milestone.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/milestone-xprotect-corporate-high-availability-synchronous-replication-failover/) * [Nedap (nedap.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/nedap-high-availability-synchronous-replication-failover/) * [Genetec SQL Server (sqlserver.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/genetec-sql-server-the-simplest-high-availability-cluster-with-synchronous-replication-and-failover-between-two-redundant-servers/) * [Bosch AMS (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/bosch-ams-the-simplest-high-availability-cluster-between-two-redundant-servers-without-shared-disk/) * [Bosch BIS (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/bosch-bis-the-simplest-high-availability-cluster-between-two-redundant-servers-without-shared-disk/) * [Bosch BVMS (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/bosch-bvms-the-simplest-high-availability-cluster-between-two-redundant-servers-without-shared-disk/) * [Hanwha Vision (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/hanwha-vision-cluster-without-shared-storage-on-a-san/) * [Hanwha Wisenet (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/hanwha-wisenet-wave-the-simplest-high-availability-cluster-between-two-redundant-servers-without-shared-disk/) - * Siemens (real-time replication and failover) --- * [Siemens Siveillance suite (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-siveillance-redundancy-high-availability-cluster-active-active/) * [Siemens Desigo CC (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-desigo-cc-redundancy-high-availability-cluster-active-active/) * [Siemens Siveillance VMS (SiveillanceVMS.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-siveillance-vms-the-simplest-high-availability-cluster-between-two-redundant-servers/) * [Siemens SiPass (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-sipass-redundancy-high-availability-cluster-active-active/) * [Siemens SIPORT (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-siport-redundancy-high-availability-cluster-active-active/) * [Siemens SIMATIC PCS 7 (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-simatic-pcs-7-redundancy-high-availability-cluster-active-active/) * [Siemens SIMATIC WinCC (hyperv.safe)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/siemens-simatic-wincc-redundancy-high-availability-cluster-active-active/) * [Architectures](#) + - * Basic architectures --- * [Overview](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-architectures/) * [Mirror Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/file-replication-byte-level-with-failover-mirror-cluster/) * [Farm Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/network-load-balancing-cluster/) * [SafeKit Console](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-smart-console-your-high-availability-cluster-in-your-pocket/) - * Advanced architectures --- * [Farm+Mirror Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/clustering-software-load-balancing-mirroring/) * [Active Active Cluster with Replicaton](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/active-active-cluster-real-time-replication/) * [N-1 Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/n-1-redundancy/) - * Hypervisor architectures --- * [Hyper-V Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/hyper-v-replication-automatic-failover-load-balancing/) * [KVM Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-kvm-high-availability-replication-automatic-failover-load-balancing/) - * Container architectures --- * [Docker Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/docker-container-high-availability-cluster-synchronous-replication-failover/) * [Podman Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/podman-the-simplest-high-availability-cluster-between-two-redundant-servers/) * [Best practises](#) + - * High availability best practises --- * [High Availability Architectures & Software Clustering Best Practices](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-architectures-and-best-practices/) * [Shared Nothing vs. Shared Disk Architecture: Choosing the Best HA Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/shared-nothing-architecture-vs-shared-disk-architecture/) * [Software clusering vs hardware clustering](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/clustering-software-vs-hardware-clustering/) * [VM HA vs. Application HA: Choose Your Redundancy Level with SafeKit](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/vm-ha-vs-application-ha/) * [High Availability and Disaster Recovery (HADR)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-disaster-recovery-hadr/) * [HA Cluster vs. Fault Tolerant System: Choosing the Right Redundancy Strategy](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-cluster-vs-fault-tolerant-system/) * [How to Implement Redundant Servers with Simple HA Software](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/how-to-implement-redundant-servers-with-a-simple-software-windows-linux/) - * Replication best practises --- * [Data Replication Techniques for High Availability: A Complete Comparison](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/data-replication-techniques/) * [Synchronous vs. Asynchronous Replication: How SafeKit Ensures Zero Data Loss?](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/synchronous-replication-vs-asynchronous-replication/) * [Byte-Level File Replication vs. Block-Level Disk Replication for HA](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/byte-level-file-replication-vs-block-level-disk-replication/) * [Alternative to SQL Server Always On: HA for Express and Standard Editions](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/alternative-always-on-sql-server-express-standard-editions/) - * Clustering best practises --- * [How a Virtual IP Address (VIP) Works in High Availability Clustering?](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/how-a-virtual-ip-address-works/) * [Handling Power Outages and Network Isolation in a HA Cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/power-outage-and-network-isolation-in-a-cluster/) * [Heartbeat, failover and quorum in a cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/heartbeat-failover-quorum-windows-linux-aix-cluster/) * [SAN vs. NAS Shared Storage for Failover Clustering: A Detailed Comparison](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/san-vs-nas-shared-storage-for-a-failover-cluster/) * [What are RPO and RTO? Definitions, Examples, and HA Strategies](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/what-is-rpo-and-rto-with-examples/) * [Microsoft NLB vs SafeKit network load balancing](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/microsoft-nlb-vmware-multicast-unicast-alternative/) * [Resources](#) + - * Free trial --- * [SafeKit free trial](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-free-trial/) * [One-month license key](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-and-load-balancing-cluster-key/) * [Demonstrations](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-solutions-ha-solutions-videos/) * [Support](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-support/) * [Free Training & Certification](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-on-line-training/) - * Technical documentations --- * [SafeKit quick installation guides](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-quick-installation-guides/) * [SafeKit user's guide](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-user-guide-82/) * [SafeKit release notes](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-release-notes-8-2/) * [SafeKit SRB](https://safekit.evidian.com/wp-content/uploads/downloads_safekit/version-82/82softwarereleasebulletin.pdf) * [Knowledge Base](https://safekit.evidian.com/wp-content/uploads/downloads_safekit/version-82/knowledge-base.pdf) - * Product information --- * [Flyer](https://safekit.evidian.com/wp-content/uploads/documents/high-availability-overview.pdf) * [White Paper - Product](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-white-paper/) * [White Paper - High Availability Guide](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-guide/) * [Technical Reference for RFI and RFP](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/high-availability-technical-reference-for-rfi-and-rfp-preparation/) * [Support](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-support/) * [Price](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/get-a-quote-safekit-en/) * [Contact](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/contact-us-for-safekit/) * [![English](https://safekit.evidian.com/wp-content/uploads/flags/us.png)](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-high-availability-software-synchronous-replication-failover/) [Eviden >](https://eviden.com/) [Products >](https://safekit.evidian.com/products/) [SafeKit: All-in-One SANless High Availability & Application Clustering Software >](https://safekit.evidian.com/) The Simplest Linux High Availability: 2-Node Synchronous Replication & Failover # The Simplest Linux High Availability: 2-Node Synchronous Replication & Failover ## How the SANless SafeKit Mirror Cluster Works with Linux **SafeKit for Linux** delivers seamless **High Availability** while significantly reducing TCO (Total Cost of Ownership). By eliminating the hardware and operational overhead of traditional clustering, SafeKit offers a lean, 2-node HA alternative to complex clustering solutions. * **All-in-One Business Continuity:** A complete solution providing **Virtual IP**, **Automatic Failover**, **Automatic Failback**, and **Real-time replication** in a single, integrated package. * **Synchronous Replication (Zero Data Loss):** Ensure absolute data integrity for transactional applications with synchronous replication, guaranteeing 0 data loss in the event of a failure. * **Flexible File-Level Protection:** SafeKit performs host-based replication at the file level, which is completely transparent for the application. It protects not just databases, but all associated folders and data. You can replicate existing folders exactly where they are installed, even on the **system disk**. * **Simplified Deployment (No AD/LDAP):** Unlike traditional clusters, there is **no need for AD/LDAP directory configuration**, removing complex installation requirements and infrastructure dependencies. * **Zero SAN Investment for HA:** Achieve full redundancy using shared-nothing architecture. It works with standard local disks, removing the need for expensive SAN hardware, fiber channel switches, and specialized storage maintenance. * **True 2-Node Efficiency:** While most solutions require a third "witness" node to prevent split-brain, SafeKit delivers a robust **2-node cluster**, saving 33% on hardware, power, and rack space. * **Hardware-Agnostic Redundancy:** Avoid vendor lock-in. Build your High Availability cluster using any server brand or internal storage type, extending the lifecycle of existing hardware and lowering replacement costs. * **Cost-Predictable Licensing:** SafeKit provides High Availability via a one-time perpetual license, ensuring predictable budgeting and eliminating the risk of annual price hikes. By consolidating **High Availability** into a lightweight software layer, SafeKit delivers enterprise-grade **redundancy and business continuity for Linux** at a fraction of the cost of traditional clustering suites. ![SafeKit High Availability Linux Cluster Architecture providing Virtual IP, Automatic Failover, Automatic Failback, and Real-time replication](https://safekit.evidian.com/wp-content/uploads/2026/02/safekit-linux-app-1024.jpg "SafeKit HA Mirror Cluster for Linux") **SafeKit HA Mirror Cluster for Linux** [⚡ Quick mirror cluster installation guide for Linux >](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-high-availability-software-synchronous-replication-failover/safekit-quick-installation-guide-for-a-new-linux-application-with-real-time-replication-and-failover/) [🧑 Contact us](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/contact-us-for-safekit/) [🎁 SafeKit free trial](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-free-trial/) [🏅 Free certification](https://training.my.evidian.com/mod/page/view.php?id=712) [💰 Perpetual license cost](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/get-a-quote-safekit-en/) ## Table of Contents * [How the SafeKit software simply implements a SANless Linux high availability cluster?](#safekit-mirror-ha-cluster) * [How the SafeKit mirror cluster works with Linux?](#safekit-mirror-cluster) * [SafeKit High Availability Limitations](#safekit-ha-limitations) * [Comparison: SafeKit for Linux vs. Other Clustering Solutions](#safekit-mirror-ha-comparison) * [Video Guide: Configuring a SafeKit Mirror HA cluster](#videoguide-safekit-mirror-cluster) * [🔍 SafeKit High Availability Navigation Hub](#hub) ## How the SafeKit software simply implements a SANless Linux high availability cluster? ### What is the SafeKit Mirror HA solution for Linux? SafeKit brings high availability to Linux between two servers of any brand. This article explains how to implement quickly a Linux cluster without shared storage on a SAN and without specific skills. The principle of the solution is to define the folders where the **Linux application** data resides, its services, a virtual IP, and checkers. SafeKit then implements **real-time replication** and **automatic failover** to ensure continuous service availability. ### Why choose a unified All-in-One HA solution over fragmented tools? Unlike "bolt-on" solutions that combine separate products for replication and clustering, **SafeKit** integrates **Virtual IP, Automatic Failover, Automatic Failback and Real-time File Replication** into a single engine. This eliminates the "house of cards" risk where OS updates break fragile links between disparate tools, provides a single point of accountability for the entire HA stack, and reduces human error by providing a single interface for Linux HA. ### Should I choose high availability at the application level or the virtual machine (VM) level? With SafeKit, you have the flexibility to choose the redundancy model that fits your needs. **VM-level redundancy** (for Hyper-V or KVM) is the simplest to implement as it replicates the entire virtual machine, requiring no knowledge of the internal application. Alternatively, **application-level redundancy** is more granular; it only replicates specific data folders and restarts the application services rather than the entire OS. While VM-level HA is easier to set up, application-level HA is hypervisor-agnostic and can run across physical, virtual, or cloud environments. ### What are the distinctive advantages of SafeKit Linux high availability compared to competitors? SafeKit differentiates itself from traditional Linux clusters through its **shared-nothing architecture** and simplified deployment. While most enterprise solutions require complex replication deployment or expensive SAN storage, SafeKit provides: * **Synchronous Replication with Zero Data Loss:** SafeKit implements 100% synchronous replication, ensuring total data integrity for transactional applications. In the event of a failure, there is **zero data loss (RPO=0)**. Furthermore, SafeKit is capable of replicating not only the Linux databases but **any other data folders** (logs, configuration files, etc.), ensuring the entire environment is mirrored. * **Simplified 2-Node Clustering:** Unlike standard clusters that often require a "witness" (a 3rd node, disk, file share) to maintain a quorum, SafeKit delivers full high availability with just two redundant servers, reducing infrastructure costs and complexity. [Learn more about our heartbeat and quorum mechanism](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/heartbeat-failover-quorum-windows-linux-aix-cluster/). * **Unified Management:** Administrators can manage Linux failover, data replication, and monitoring through a single SafeKit console. This makes high availability accessible to teams without specialized "cluster admin" expertise. * **Custom Checkers:** SafeKit goes beyond basic service monitoring; it **offers checkers** to monitor the health of the Linux process. The system is highly extensible, allowing for the addition of custom checkers tailored to your environment. ### How does SafeKit reduce the TCO (Total Cost of Ownership) for Linux compared to standard clustering? Unlike traditional high-availability solutions, SafeKit is designed to operate with the **absolute minimum infrastructure overhead**, without compromising reliability. Key savings compared to traditional failover cluster include: * **Zero Storage Costs:** SafeKit uses a shared-nothing architecture that works with local disks. This removes the need for expensive SAN hardware, iSCSI networks, or complex vSAN configurations. * **No Enterprise Edition Required:** While native replication mechanim may require expensive Enterprise licensing, SafeKit **does not need the Enterprise edition**. It works seamlessly with standard edition and even the **free edition**, providing high-end availability at a fraction of the cost. * **True 2-Node Efficiency:** Unlike standard clusters that often require a "witness" (a 3rd node, disk, or file share) to maintain a quorum, SafeKit delivers full high availability with just **two redundant servers**. * **No Forced Subscriptions:** SafeKit offers a **perpetual license**. You own your software, avoiding the "subscription trap" and unpredictable annual price hikes common with modern cloud-only or subscription-based models. * **Low Operational Expense (OPEX):** As a plug-and-play solution, it requires no specialized training or expensive external consultancy for maintenance, unlike complex open-source clustering tools. * **CPU-Independent Pricing:** Licensing is independent of the number of CPUs or cores. With just two licenses for two nodes, you can protect Linux against failures. ### Is it possible to set up a Linux mirror cluster without clustering skills? Yes. This article explains how to [**quickly implement a Linux mirror cluster**](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/linux-high-availability-software-synchronous-replication-failover/safekit-quick-installation-guide-for-a-new-linux-application-with-real-time-replication-and-failover/) without the need for specialized SAN management or complex HA clustering skills. By using SafeKit’s **automated failover scripts** to handle the replication and restart of **Linux**, you get a robust redundancy solution that is significantly simpler to deploy and maintain than traditional clustering solutions. ### Beyond Linux, which applications and environments can SafeKit protect? SafeKit is a versatile high-availability solution **for both Windows and Linux**. It enables **synchronous real-time replication** and automatic failover for a wide range of critical workloads, including: * **Virtual & Physical Environments:** Complete Hyper-V or KVM virtual machines. * **Container Orchestration:** Docker, Podman, and K3s (Kubernetes) environments. * **Data & Services:** Individual file directories, services, and various databases. * **Cloud Infrastructure:** High availability for Cloud applications. SafeKit also provides **Farm Clusters** with native **Network Load Balancing and Failover** for stateless applications like **Web Servers**. [Explore the full list of supported HA solutions here.](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/cluster-configuration/) ## How the SafeKit mirror cluster works with Linux? ### Step 1. Real-time replication Server 1 (PRIM) runs the Linux application. Clients are connected to a [virtual IP address](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/how-a-virtual-ip-address-works/#mirror). SafeKit replicates in real time modifications made inside files through the network. ![File replication at byte level in a mirror Linux cluster](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20300%20169'%3E%3C/svg%3E)![File replication at byte level in a mirror Linux cluster](https://safekit.evidian.com/wp-content/uploads/2023/02/safekit-prim-second-300.png) The replication is [synchronous](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/synchronous-replication-vs-asynchronous-replication/) with no data loss on failure contrary to asynchronous replication. You just have to configure the names of directories to replicate in SafeKit. There are no pre-requisites on disk organization. Directories may be located in the system disk. ### Step 2. Automatic failover When Server 1 fails, Server 2 takes over. SafeKit switches the virtual IP address and restarts the Linux application automatically on Server 2. The application finds the files replicated by SafeKit uptodate on Server 2. The application continues to run on Server 2 by locally modifying its files that are no longer replicated to Server 1. ![Failover of Linux in a mirror cluster](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20300%20169'%3E%3C/svg%3E)![Failover of Linux in a mirror cluster](https://safekit.evidian.com/wp-content/uploads/2023/02/safekit-stop-alone-300.png) The failover time is equal to the fault-detection time (30 seconds by default) plus the application start-up time. ### Step 3. Automatic failback Failback involves restarting Server 1 after fixing the problem that caused it to fail. SafeKit automatically resynchronizes the files, updating only the files modified on Server 2 while Server 1 was halted. ![Failback in a mirror Linux cluster](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20300%20169'%3E%3C/svg%3E)![Failback in a mirror Linux cluster](https://safekit.evidian.com/wp-content/uploads/2023/02/safekit-resynchro-alone-300.png) Failback takes place without disturbing the Linux application, which can continue running on Server 2. ### Step 4. Back to normal After reintegration, the files are once again in mirror mode, as in step 1. The system is back in high-availability mode, with the Linux application running on Server 2 and SafeKit replicating file updates to Server 1. ![Return to normal operation in a mirror Linux cluster](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20300%20169'%3E%3C/svg%3E)![Return to normal operation in a mirror Linux cluster](https://safekit.evidian.com/wp-content/uploads/2023/02/safekit-second-prim-300.png) If the administrator wishes the application to run on Server 1, this can be done manually through the web console at an appropriate time, or automatically through configuration. ### How to configure a SafeKit Mirror Cluster for Linux? ![SafeKit Web Console: High Availability configuration dashboard for Linux showing heartbeat networks, virtual IP setup, and real-time directory replication for a mirror cluster.](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20763%20497'%3E%3C/svg%3E)![SafeKit Web Console: High Availability configuration dashboard for Linux showing heartbeat networks, virtual IP setup, and real-time directory replication for a mirror cluster.](https://safekit.evidian.com/wp-content/uploads/2026/01/safekit-mirror-cluster-config.png) The **SafeKit web console** provides an intuitive interface to orchestrate high availability for your critical applications. In just a few steps, you can configure a **SafeKit mirror cluster** to ensure business continuity: * **Application Failover (Macros Tab):** Define the specific application services to be automatically restarted in the event of a failure. * **Heartbeat network(s):** Dedicated communication path(s) used by cluster nodes to continuously monitor each other's health and availability and synchronize failover decisions. * **Virtual IP Management:** Set up the Virtual IP (VIP) for transparent client reconnection after a failover. * **Real-Time Replication:** Select the critical directories for host-based, synchronous byte-level replication. * **Checkers:** Monitor the application's health and trigger automatic recovery if a process failure is detected. The SafeKit cluster includes a dedicated split-brain checker to resolve network isolation issues without the need for a third witness machine or an additional heartbeat network. Learn more about [heartbeat, failover and quorum in a cluster](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/heartbeat-failover-quorum-windows-linux-aix-cluster/). ### How to monitor a SafeKit mirror cluster for Linux? ![SafeKit Web Console: Real-time monitoring of a 2-node mirror cluster for Linux showing PRIM and SECOND states with active data replication.](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20604%20412'%3E%3C/svg%3E)![SafeKit Web Console: Real-time monitoring of a 2-node mirror cluster for Linux showing PRIM and SECOND states with active data replication.](https://safekit.evidian.com/wp-content/uploads/2026/05/mirror-monitoring-prim-second.png) The **SafeKit management console** offers a unified view of your high availability infrastructure. It allows administrators to monitor the **operational state** of the cluster and track data synchronization in real-time. For a 2-node mirror cluster, the console clearly displays the roles of each server: * **PRIM (Primary):** The active node currently running the application and managing the Virtual IP. It performs writes to the local storage and real-time replication to the secondary node. * **SECOND (Secondary):** The standby node receiving synchronous byte-level updates. It is ready to take over instantly if the Primary fails. * **ALONE State:** Visually alerts you when the cluster is running on a single node (e.g., during maintenance or after a failure), indicating that redundancy is temporarily lost. * **Resynchronization Progress:** When a failed node recovers, its status turns orange during background data reintegration, ensuring no downtime during the "return to normal" phase. Beyond simple status icons, the interface provides **one-click failover orchestration**, allowing you to manually reassign the primary role for planned maintenance while ensuring continuous availability for user activity. ## SafeKit High Availability Limitations ### Why a replication of a few Tera-bytes? Resynchronization time after a failure ([step 3](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/file-replication-byte-level-with-failover-mirror-cluster/#mirrorcluster)) * 1 Gb/s network ≈ 3 Hours for 1 Tera-bytes. * 10 Gb/s network ≈ 1 Hour for 1 Tera-bytes or less depending on disk write performances. #### Alternative * For a large volume of data, use [external shared storage](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/san-vs-nas-shared-storage-for-a-failover-cluster/). * More expensive, more complex. ### Why a replication < 1,000,000 files? * Resynchronization time performance after a failure ([step 3](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/file-replication-byte-level-with-failover-mirror-cluster/#mirrorcluster)). * Time to check each file between both nodes. #### Alternative * Put the many files to replicate in a virtual hard disk / virtual machine. * Only the files representing the virtual hard disk / virtual machine will be replicated and resynchronized in this case. ### Why a failover ≤ 32 replicated VMs? * Each VM runs in an independent mirror module. * Maximum of 32 mirror modules running on the same cluster. #### Alternative * Use an external shared storage and another VM clustering solution. * More expensive, more complex. ### Why a LAN/VLAN network between remote sites? * Automatic failover of the [virtual IP address](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/how-a-virtual-ip-address-works/) with 2 nodes in the same subnet. * Good bandwidth for resynchronization ([step 3](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/file-replication-byte-level-with-failover-mirror-cluster/#mirrorcluster)) and good latency for [synchronous replication](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/synchronous-replication-vs-asynchronous-replication/) (typically a round-trip of less than 2ms). #### Alternative * Use a [load balancer for the virtual IP address](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/how-a-virtual-ip-address-works/) if the 2 nodes are in 2 subnets (supported by SafeKit, especially in the cloud). * Use backup solutions with asynchronous replication for high latency network. ## Comparison: SafeKit for Linux vs. Other Clustering Solutions | Feature | SafeKit for Linux | Shared Storage Failover Clustering | Database Replication | | --- | --- | --- | --- | | Architecture | SANless (Shared-Nothing) | Shared Storage (SAN/NAS) | Shared-Nothing | | Application Reconfiguration | None (Runs in-place) | Required (Move Data to Shared Disk) | None | | Replication Scope | Whole Application (DB + Config + Logs) | Shared Disk Data | Database Data Only | | Replication Type | Synchronous (Zero RPO) | Synchronous (via SAN) | Depends on Editions (Often Async) | | Failover/Failback Logic | Fully Automatic | Fully Automatic | Often Manual or Complex | | AD/LDAP Dependency | Independent (No AD required) | Required on Windows (Active Directory) | Independent | | Deployment Complexity | Low (< 30 Minutes) | High (AD, Storage, Quorum) | Medium (Replication Only, No Failover) | ### Conclusion By eliminating the need for a SAN and simplifying deployment—removing dependencies such as **Active Directory** and specialized **Quorum** configurations—SafeKit offers a lean, hardware-agnostic HA alternative. This results in a significantly lower TCO while ensuring that your Linux environment remains resilient with zero data loss and automated recovery. ## Video Guide: Configuring a SafeKit HA mirror cluster ### [SafeKit Video: Application-Level Clustering (8:47)](https://www.youtube.com/embed/mGwEguDnnH0?rel=0&autoplay=1&cc_load_policy=1&hl=en&cc_lang_pref=en) In this video, discover how SafeKit implements a **mirror HA cluster** without the complexity of a SAN. While this demonstration uses Microsoft SQL Server, the solution works identically for other databases and applications. ### Video Highlights 1. [2 nodes with SQL Server](https://www.youtube.com/embed/mGwEguDnnH0?rel=0&autoplay=1&start=0&end=32&cc_load_policy=1&hl=en&cc_lang_pref=en) (0:32) 2. [Configure the cluster and the mirror.safe module](https://www.youtube.com/embed/mGwEguDnnH0?rel=0&autoplay=1&start=32&end=270&cc_load_policy=1&hl=en&cc_lang_pref=en) (3:58) 3. [Start and test SQL replication, migration, failover on crash](https://www.youtube.com/embed/mGwEguDnnH0?rel=0&autoplay=1&start=270&cc_load_policy=1&hl=en&cc_lang_pref=en) (4:17) ## 🔍 SafeKit High Availability Navigation Hub Explore SafeKit: Features, technical videos, documentation, and free trial | Resource Type | Description | Direct Link | | --- | --- | --- | | **Key Features** | Why Choose SafeKit for Simple and Cost-Effective High Availability? | [See Why Choose SafeKit for High Availability](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#why-choose-safekit-for-ha "Discover SafeKit features for simple and cost-effective high availability") | | **Use Cases** | Explore How SafeKit Ensures the High Availability of Critical Infrastructure | [See All Use Cases](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-use-cases "Explore SafeKit high availability use cases") | | **Deployment Model** | All-in-One SANless HA: Shared-Nothing Software Clustering | [See SafeKit All-in-One SANless HA](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#all-in-one-sanless-ha "Learn about all-in-one SANless high availability with shared-nothing software clustering") | | **HA Strategies** | SafeKit: Infrastructure (VM) vs. Application-Level High Availability | [See SafeKit HA & Redundancy: VM vs. Application Level](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-ha-redundancy-choices "Compare VM-level redundancy with SafeKit application-level high availability strategies") | | **Technical Specifications** | Technical Limitations for SafeKit Clustering | [See SafeKit High Availability Limitations](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-ha-limitations "Technical requirements and limitations for SafeKit application clustering") | | **Proof of Concept** | SafeKit: High Availability Configuration & Failover Demos | [See SafeKit Failover Tutorials](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-failover-tutorials "Step-by-step videos on SafeKit high availability, from installation to automated failover") | | **Architecture** | How the SafeKit Mirror Cluster works (Real-Time Replication & Failover) | [See SafeKit Mirror Cluster: Real-Time Replication & Failover](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-mirror-cluster "See technical architecture and failover mechanism of SafeKit Mirror Cluster") | | **Architecture** | How the SafeKit Farm Cluster works (Network Load Balancing & Failover) | [See SafeKit Farm Cluster: Network Load Balancing & Failover](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-farm-cluster "Technical overview of SafeKit Farm Cluster architecture with network load balancing") | | **Competitive Advantages** | Comparison: SafeKit vs. Traditional High Availability (HA) Clusters | [See SafeKit vs. Traditional HA Cluster Comparison](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-ha-comparison "Detailed comparison of SafeKit software vs traditional hardware-based HA clusters") | | **Technical Resources** | SafeKit High Availability: Documentation, Downloads & Trial | [See SafeKit HA Free Trial & Technical Documentation](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-ha-technical-resources "Access SafeKit free trial, technical documentation, and high availability white papers") | | **Pre-configured Solutions** | SafeKit Application Module Library: Ready-to-Use HA Solutions | [See SafeKit High Availability Application Modules](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/#safekit-ha-application-modules "Browse the library of pre-configured SafeKit modules for automated application failover") | [Contact us >](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/contact-us-for-safekit/) [SafeKit free trial >](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/safekit-free-trial/) [Get a quote >](https://safekit.evidian.com/products/high-availability-software-for-application-clustering/get-a-quote-safekit-en/) * © Eviden, all rights reserved * |[Eviden privacy](https://eviden.com/privacy-policy) * |[Eviden terms and conditions](https://eviden.com/terms-and-conditions) * |[Eviden](https://eviden.com) [![eviden-logo](https://safekit.evidian.com/wp-content/uploads/2026/01/eviden-logo-black-265-54.png)](https://eviden.com/) We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. 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