Evidian SafeKit: Simple, Cost-Effective High Availability Software

SafeKit provides the following features for Windows and Linux in a single software product:

• Load balancing
• Synchronous real-time file replication
• Automatic application failover
• Automatic failback after a server failure

SafeKit eliminates the following requirements:

• Network load balancers or dedicated proxy servers
• Shared disks or replicated SAN storage
• Enterprise editions of operating systems and databases
• Specialized cluster maintenance skills

SafeKit solves:

• Hardware failures (20% of problems), including the complete failure of a computer room
• Software failures (40% of problems), including restart of critical processes
• Human errors (40% of problems) thanks to its ease of use

You can implement real-time replication and failover for:

• All types of applications, file directories, and services
• Databases
• Complete Hyper-V or KVM virtual machines
• Docker, Podman, and cloud applications

No. SafeKit is simple to deploy—no advanced expertise required.

No. SafeKit runs on your existing servers, virtual machines, or in the cloud—no shared disks or SAN storage needed.

No. SafeKit works with standard Windows and Linux editions and does not need enterprise database licenses.

This platform-independent software is ideal for partners reselling critical applications who need to offer customers a simple, cost-effective high availability (HA) and system redundancy option, without the complexity and expense of SANs (Storage Area Networks). SafeKit’s core features — load balancing, real-time data replication, and automatic failover — significantly simplify the integration of HA into any service or product offering.

With a proven track record and numerous deployments in over 30 countries through our extensive partner network, SafeKit is recognized as the easiest and fastest HA solution to implement for critical systems. This includes sectors like video management systems (VMS), access control, building management (BMS), SCADA software, automated logistics, and critical air/rail traffic control, ensuring maximum uptime across the board.

SafeKit offers a complete, free, and open-access resource kit to support its partners, including free trials, comprehensive online training modules, and the opportunity to obtain official SafeKit certification at no cost. These tools enable partners to rapidly acquire the necessary technical skills to effectively deploy and provide world-class support for the solution, minimizing deployment time and reducing the learning curve.

In this solution, only the application data are replicated. In the event of a failure, only the application is restarted, not the entire operating system or VM.

In this solution, the full Virtual Machine (VM) is replicated, including both the Application and the Operating System (OS). In the event of a failure, the full VM is restarted.

Resynchronization time after a failure (step 3)

• 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.
• More expensive, more complex.

• Resynchronization time performance after a failure (step 3).
• 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.

• 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.

• Automatic failover of the virtual IP address with 2 nodes in the same subnet.
• Good bandwidth for resynchronization (step 3) and good latency for synchronous replication (typically a round-trip of less than 2ms).

Alternative

• Use a load balancer for the virtual IP address 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.

Server 1 (PRIM) runs the application. Clients are connected to a virtual IP address. SafeKit replicates in real time modifications made inside files through the network.

The replication is synchronous 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.

When Server 1 fails, Server 2 takes over. SafeKit switches the virtual IP address and restarts the 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.

The failover time is equal to the fault-detection time (30 seconds by default) plus the application start-up time.

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 takes place without disturbing the application, which can continue running on Server 2.

After reintegration, the files are once again in mirror mode, as in step 1. The system is back in high-availability mode, with the application running on Server 2 and SafeKit replicating file updates to Server 1.

If the administrator wishes the application to run on Server 1, he/she can execute a "swap" command either manually at an appropriate time, or automatically through configuration.

The network load balancing algorithm inside the network filter is based on the identity of the client packets (client IP address, client TCP port). Depending on the identity of the client packet input, only one filter in a server accepts the packet; the other filters in other servers reject it.
Once a packet is accepted by the filter on a server, only the CPU and memory of this server are used by the application that responds to the request of the client. The output messages are sent directly from the application server to the client.
If a server fails, the farm heartbeat protocol reconfigures the filters in the network load balancing cluster to re-balance the traffic on the remaining available servers.

With a stateful application, there is session affinity. The same client must be connected to the same server on multiple TCP sessions to retrieve its context on the server. In this case, the SafeKit load balancing rule is configured on the client IP address. Thus, the same client is always connected to the same server on multiple TCP sessions. And different clients are distributed across different servers in the farm.
With a stateless application, there is no session affinity. The same client can be connected to different servers in the farm on multiple TCP sessions. There is no context stored locally on a server from one session to another. In this case, the SafeKit load balancing rule is configured on the TCP client session identity. This configuration is the one which is the best for distributing sessions between servers, but it requires a TCP service without session affinity.

This table provides the SafeKit installation files for the current version, organized by operating system and installer type.

➡️ Go to v7.5 Archives

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Explore our product marketing documentation for SafeKit HA software, which includes a detailed data sheet, product white paper, and technical overview.

• SafeKit High Availability Cluster Data Sheet (PDF)
• High Availability Cluster Technology White Paper (PDF)
• SafeKit High Availability Technical Overview (DOCX)

This table presents the SafeKit High Availability (HA) solutions, categorized by application and operating environment (Databases, Web Servers, VMs, Cloud). Identify the specific pre‑configured .safe module (e.g., mirror.safe, farm.safe, and others) required for real‑time replication, load balancing, and automatic failover of critical business applications on Windows or Linux. Simplify your HA cluster setup with direct links to quick installation guides, each including a download link for the corresponding .safe module.

A SafeKit .safe module is essentially a pre‑configured High Availability (HA) template that defines how a specific application will be clustered and protected by the SafeKit software. In practice, it contains a configuration file (userconfig.xml) and restart scripts.