Application availability Archives - SIOS SANless clusters

SIOS Enterprise Support Guide: What Your Plan Covers

May 30, 2026 by Jason Aw Leave a Comment

SIOS Enterprise Support Guide: What Your Plan Covers

What’s Included in Your SIOS Enterprise Support Plan?

Here are some quick tips for what is covered and not covered with Enterprise level support, and where to go for additional information based on three common scenarios.

24/7 Support for Critical System Downtime

Scenario 1: System Down After Hours
Joan’s team: It’s 7 pm EST on Sunday. The routine switchover between SIOS LifeKeeper cluster nodes should have been simple. But something unexpected happened, resulting in the switchover failure. Despite all of the team’s efforts to resolve the issue, the cluster remains down. Joan needs help, but she is not sure that her SIOS Technical support plan covers weekends or how long it will take to get a support person on the phone.

Customers who have purchased (or renewed) their Enterprise level support prior to an incident have access to receive support 24 hours a day, 7 days a week. This support includes weekends and holidays to address Critical Issues. Critical Issues mean down production systems or applications, where Customer data cannot be accessed using SIOS Programs. For all Priority 1 (critical) issues, where normal operation results in the loss of access to your production data, SIOS provides a 2-hour response time.

If Joan has valid Enterprise support, she will be able to reach out to the SIOS support team, and her after-hours issue will be covered.

Installation and Configuration Support

Scenario 2: Installation Assistance Needed
Scott’s team: It’s 4 pm EST on Thursday. The approvals have been completed for the new infrastructure project, including the required high availability configuration for critical applications and data. At the kickoff, the stakeholders moved the date for go-live. As a result, the team needs to get the systems installed and configured quickly to avoid service interruption. Scott’s team knows how to configure the application and server, but they want to be doubly sure they install the HA solution correctly. They need help, but Scott’s not sure that their support plan covers help with installation errors.

Since Scott’s team is in the deployment phase, the new infrastructure project involves systems that have not been validated or successfully put into production. If Scott’s team has valid SIOS Enterprise level support, he will have access to SIOS product documentation and installation pointers. However, assistance with installation and configuration is not covered under Scott’s Enterprise support, but he can contact his SIOS sales representative to arrange a paid Professional Services installation engagement. This engagement will ensure that Scott’s team gets the assistance they need to properly install, configure, and validate their cluster. SIOS provides a wide range of professional services designed to help customers quickly and cost-effectively implement, manage, and maintain their HA environments.

Root Cause Analysis (RCA) After Failover

Scenario 3: Post-Failover RCA Support
Amol’s team: It’s 2 am EST on Tuesday. An alert has been sent out to the entire application team at AjaxBjax Corp. The cluster protecting the company’s most critical application system is conducting a failover. Amol checks the application dashboard and discovers that the failover was successful and all applications are functioning. However, Amol knows that management will want some explanations and assurances. Amol wants to make sure that all application services are up and functioning, but he isn’t sure that their support plan covers whatever this is.

Amol’s team is looking for an RCA and the confidence that their system is going to continue to be operational. Amol’s data is accessible, and his application is fully functional. His system is not a critical down production server, nor a P1 issue. However, if AjaxBjax Corp has valid Enterprise support for their cluster, they will be able to reach out to the SIOS support team for guidance around the clock (US East), Monday through Friday, for RCA issues. Amol’s 2 am call will be routed to one of the knowledgeable SIOS support centers, where the team will begin working with Amol.

Additional Questions About Contacting SIOS Support

Amol and Joan were able to contact support via the Support Hotline (US: 877.457.5113; International: +1.803.808.4270) with coverage included by their Enterprise Support. Scott was able to receive the help he needed, not from the Support team, but through the purchase of services to assist with configuration and installation. But what about other scenarios, where can Scott, Amol, Joan, and others find more about their support levels and support details? Or whether their product has reached the maintenance or extended support phases?

When you need to find additional information about your support agreement, you can consult the SIOS Technical Support Agreement (TSA), which is included with each order. The TSA is also conveniently located on our download site, and can be requested via an email to the SIOS Support Team at support@us.sios.com. Additionally, product schedules and support tier information can be found online at the Product Lifecycle page.

Customers who already know what’s covered under their plan, but need help with a problem, answers to a general question, root cause analysis, the latest software, or pointers to more information can open a new case via the Support Portal website or via email to the Support Inbox at support@us.sios.com. Once your case is created, the team will work to provide timely responses and resolution.

Author: Cassius Rhue VP, Customer Experience

Reproduced with permission from SIOS

3 Common Configuration Mistakes That Cause Clusters to Break

May 5, 2026 by Jason Aw Leave a Comment

3 Common Configuration Mistakes That Cause Clusters to Break

Why Cluster Configuration Matters for High Availability

High availability isn’t just about preventing downtime; it’s about protecting revenue, reputation, and customer trust. Surprisingly, some failover clusters fall short when they’re needed most, not because of flaws in the technology itself, but because of improper cluster configuration.

Whether you’re using Windows Server Failover Clustering (WSFC) with DataKeeper or a LifeKeeper + DataKeeper setup, proper cluster configuration is what separates true high availability from a false sense of security. When configuring SIOS products, many guardrails are already put in place to prevent users from making configuration mistakes, such as comm path redundancy warnings, port conflict validation, pagefile warnings, disk size guidance, etc. However, SIOS cannot control your entire OS, storage, and network, so some consideration must be taken by the user to ensure setup and maintenance are performed properly.

Here are three common mistakes that quietly undermine clustered environments and how modern solutions help eliminate the risk.

Mistake #1: Network Configuration That Can’t Handle Real-World Failures

Failover clustering depends on continuous communication between nodes. But in many environments, networks are configured “just enough” to function but not enough to survive disruption.

Common issues include:

Heartbeat and replication traffic are competing with application traffic
Incorrect DNS settings or IP address configuration
Firewall rules are blocking communication or replication ports.
High latency between nodes

When network instability occurs, clusters may trigger unnecessary failovers or, worse, fail to fail over at all.

High Availability Network Configuration Best Practices

Modern high availability strategies isolate cluster communication and replication traffic, ensuring stability even under load. Solutions like SIOS LifeKeeper continuously monitor application health, not just server availability, adding intelligence beyond basic node detection.

The result? Fewer false failovers. Faster recovery. Greater confidence.

Mistake #2: Quorum Misconfiguration That Brings Down the Entire Cluster

Quorum is the decision-making logic of a cluster. If configured incorrectly, even a minor outage can cause the entire environment to go offline.

In Windows Server environments, two-node clusters without a properly configured witness are especially vulnerable. A simple network interruption can result in total service disruption.

This isn’t a rare edge case; it is one of the most common causes of unexpected downtime in failover environments.

Quorum Configuration Best Practices for High Availability

A well-designed HA strategy accounts for:

Proper witness placement
Accurate quorum configuration
Application-level monitoring

SIOS LifeKeeper enhances traditional quorum-based decision-making with intelligent resource dependency management. Instead of relying solely on infrastructure signals, it ensures applications are restarted in the correct order and fully operational before declaring success.

Availability isn’t just about staying online; it’s about staying operational.

Mistake #3: Data Replication Missteps That Break Failover

Traditional clustering often relied on shared storage, which introduced cost and complexity. Today, many organizations use host-based replication to eliminate that dependency.

With SIOS DataKeeper, volumes are mirrored between nodes, enabling high availability without expensive SAN infrastructure.

But replication only protects you if it’s configured correctly.

Common mistakes include:

Failing to fully synchronize volumes before production cutover
Mismatched drive letters or mount points
Insufficient bandwidth for replication
Lack of replication health monitoring

When a failover occurs with out-of-sync data, recovery may be delayed, or worse, data integrity may be compromised. However, with proper planning and configuration at the start,t the benefits to your organization are unparalleled.

Data Replication Best Practices for High Availability

By combining SIOS LifeKeeper or Windows clustering with SIOS DataKeeper mirrored volumes, organizations eliminate shared storage complexity while maintaining enterprise-grade availability.

SIOS DataKeeper provides:

Real-time block-level replication
Monitoring of mirror health and synchronization
Seamless integration with WSFC
Flexibility across physical, virtual, and cloud environments

Why Basic Clustering Isn’t Enough Anymore

Traditional failover clustering focuses on server uptime. Modern businesses require application uptime.

That’s where the combination of SIOS DataKeeper with SIOS LifeKeeper or Windows Server Failover Clustering creates a more resilient architecture.

Together, they provide:

Intelligent application monitoring
Policy-based failover automation
Storage flexibility without requiring shared SANs
Cloud-ready high availability

Build a More Resilient Cluster Before Failure Happens

Failover clusters are not immune to failure, and their reliability often hinges on meticulous attention to detail. Common reasons for failure include:

1. Fragile or inconsistent network configurations

2. Ineffective quorum planning

3. Improperly set up data replication

Achieving seamless continuity instead of costly downtime requires selecting the right high availability strategy and thoroughly validating it before disaster strikes. Proactive planning and careful configuration can make all the difference.

Request a demo to see how SIOS LifeKeeper and SIOS DataKeeper help prevent cluster configuration mistakes and keep critical applications available.

Author: Connor Toohey, Sr. Product Support Engineer

Reproduced with permission from SIOS

Broadcom/VMware: Time To Decouple High Availability From Your Hypervisor

March 24, 2026 by Jason Aw Leave a Comment

Broadcom/VMware: Time To Decouple High Availability From Your Hypervisor

If you are an IT Architect, Admin, or Site Reliability Engineer (SRE) managing critical workloads on VMware, your 2026 likely began with a singular headache: The Renewal. Since the Broadcom acquisition, the “Broadcom Tax” has become a well-known cost. Between the elimination of perpetual licenses, mandatory shifts to massive subscription bundles, and aggressive 72-core minimums, “standardizing on VMware” has become an exercise in forced over-provisioning.

But there is a risk greater than the price hike: the cost of application downtime.

The “VM Restart” Fallacy: Why VMware HA Isn’t True High Availability

For years, the industry has mistaken “VMware HA” for true High Availability. If a host fails, VMware restarts the VM on another server. While this is a fast reboot, it is not High Availability.

VMware HA only monitors the physical server’s “heartbeat” to determine whether the host is operational or not. It is blind to the world inside the VM. It cannot detect a database that is hung, application services that are deadlocked, or storage that is unavailable.

Today’s mission-critical ecosystems—SAP HANA, SQL Server, Oracle, and AI-driven GPU systems—require more than a “power cycle” approach. They require application-level protection.

SIOS LifeKeeper: True HA via Application-Aware Intelligence

SIOS LifeKeeper provides visibility across your application environment: network, storage, OS, and database layers. It ensures rapid, Application-Aware Failover in compliance with application-specific best practices to deliver reliable uptime, not just a fast reboot.

While Broadcom’s licensing model effectively taxes your growth and tethers you to their ecosystem, SIOS offers true architectural freedom. Our platform-agnostic licensing allows you to migrate workloads to AWS, Azure, or alternative hypervisors without losing your HA protection. With SIOS, you aren’t just buying software; you’re securing an exit strategy from vendor lock-in.

Slashing TCO After VMware Pricing Changes: Protect the App, Not the Hypervisor

Broadcom not only requires you to buy subscription licenses, but it often requires you to upgrade your entire VMware stack or purchase bloated subscription tiers just to access the HA features needed for a single Tier-1 application.

Why upgrade your entire infrastructure license to protect one SQL Server or SAP instance? SIOS provides enterprise-class HA that lives with your application, regardless of which VMware “bundle” the Broadcom mandate. SIOS also gives you the flexibility to purchase subscription or perpetual licenses.

Eliminate the Cost and Complexity of SANs and vSAN Dependencies

Many new VMware bundles push customers toward vSAN, in environments where every millisecond counts, SIOS DataKeeper allows you to build clusters using local, high-performance NVMe storage. You get the protection of a cluster without the proprietary complexity or the “storage tax” of a virtual SAN.

SIOS delivers the capabilities—such as advanced data replication—that VMware typically gates behind its most expensive tiers. By decoupling HA from the hypervisor, you can maintain world-class uptime on more economical VMware licenses, potentially saving six or seven figures on your next renewal.

VMware HA vs. SIOS LifeKeeper and DataKeeper

Feature	VMware HA (vSphere Foundation)	SIOS LifeKeeper & DataKeeper
Failover Trigger	Host/Hardware failure only.	Application, OS, Storage, or Network failure.
App Intelligence	None. It’s a “black box” restart.	Recovery Kits for SAP, SQL, Oracle, & more.
Cloud Flexibility	Requires specific VMware Cloud stacks.	Native in AWS, Azure, GCP, or Hybrid.
Storage Model	Dependent on vSAN or Shared Storage.	SANless Clusters via local NVMe/SSD.
Licensing	Complex, Core-based, Bundle-heavy.	Predictable, portable, and application-focused. Your choice of perpetual or subscription.

Reclaim Your Infrastructure Freedom with Application-Level High Availability

SIOS gives you the flexibility to maintain high availability on your own terms while you evaluate your long-term relationship with Broadcom.

By choosing SIOS, you gain the freedom to move workloads between VMware, Nutanix, or the Public Cloud without rewriting scripts or retraining your team. You get uptime determined by the health of the application environment, not just the server’s power light.

If your upcoming renewal feels like a dead end, it’s time to move your High Availability out of the hypervisor and into the application layer.

Request a demo today to see how SIOS delivers application-level high availability across VMware, cloud, and hybrid environments.

Author: Margaret Hoagland, VP Global Sales and Marketing at SIOS

Reproduced with permission from SIOS

ARKs and Their Use Cases

February 1, 2026 by Jason Aw Leave a Comment

ARKs and Their Use Cases

Application Recovery Kits (ARKs) play a critical role in application-aware high availability (HA).

Cassius Rhue demystifies ARKs, explaining how this software add-on extends high availability beyond basic infrastructure protection by delivering intelligent, application-aware recovery. Cassius walks through real-world use cases, highlights the industries that benefit most from ARKs, and clears up common misconceptions about how they work.

Listen to the full conversation in this podcast to better understand the real business value of application-aware HA.

Reproduce with permission from SIOS

The Importance of Proper Memory Allocation in HA Environments

December 23, 2025 by Jason Aw Leave a Comment

The Importance of Proper Memory Allocation in HA Environments

Proper memory allocation is a critical yet often overlooked component in any highly available (HA) environment. When a server begins to experience memory allocation issues, the effects can transpire throughout the entire cluster, impacting application performance, slowing down replication, and even causing failover failures. In more severe cases, memory exhaustion can interrupt SIOS tools such as DataKeeper and LifeKeeper, further increasing the risk of unpredictable and unintentional behavior. Understanding the role memory plays in HA environments is key to maintaining stability, performance, and predictable failover behavior.

Below, we will explore why proper memory allocation matters, what symptoms to watch for, and how memory-related issues can impact the reliability of your cluster in LifeKeeper/DataKeeper environments.

Common Symptoms of Memory Allocation Issues

1. Replication Stalls or Unexpected Mirror Hangs/Application Termination

One of the most noticeable effects of low memory is degraded replication performance. Products like DataKeeper depend on consistent access to system memory for buffering write operations. When memory is constrained, queues begin to fill, replication slows, and in some cases, the mirror may be hung due to resource exhaustion. This can lead to resync operations that take significantly longer than expected, especially with respect to environments with high write rates. In unison, non-graceful terminations of the DataKeeper application can cause certain processes to be left unmonitored/unhandled, leading to unexpected behavior upon “starting” the DataKeeper service again.

2. Slow Application Response or Service Delays

When a system is running low on memory, the operating system may begin paging or swapping active processes. In HA environments running applications such as SQL Server, this can cause slow queries, delayed responses, and high disk activity as memory pages are constantly moved. These delays often cascade into longer failover times, as services take longer to gracefully stop or restart during a failover event.

3. Increased Risk of False Failovers

High availability solutions depend on timely heartbeat communication between nodes. When memory is exhausted, threads responsible for sending or processing heartbeat messages may be delayed. Even small delays can make a healthy node appear unresponsive, leading to unnecessary failovers or, in worst-case scenarios, split-brain events.

4. Kernel or System Logs Showing Memory Pressure

Memory starvation often results in specific system messages (Windows or Linux). These may include warnings about low available memory, paging activity spikes, or processes being terminated by the OS to reclaim memory. For systems running replication drivers or HA services, these warnings often precede more significant issues.

5. Unpredictable Performance in Virtual or Cloud Environments

In virtualized environments, memory issues can appear even when a VM reports “available” RAM. Hypervisors like VMware, Hyper-V, or cloud platforms may throttle memory access through techniques such as ballooning or overcommitment. This can silently impact VM performance, causing replication delays, heartbeat issues, etc., without obvious indications as to the root cause of the issue(s).

Tools for Diagnosing Memory Allocation Issues in HA Environments

Performance Monitor / Task Manager (Windows)
Useful for identifying memory pressure, paging activity, and process-level consumption. Look for: Highly committed memory values.
- Large paging file usage
- Processes consuming excessive RAM
Event Viewer (Windows) or journalctl / dmesg (Linux)
Memory pressure often leaves clues in system logs. Watch for:
- “Low Memory” warnings
- Failed memory allocations
- Replication driver warnings indicating resource exhaustion
top, htop, or free (Linux)
These tools can reveal memory saturation, swap usage, and services using disproportionate amounts of RAM.
Hypervisor Tools ( vSphere (VMware) / Hyper-V Manager (Hyper-V) / Cloud Platform Managers) These tools identify ballooning, swapping, host-level contention, or overcommitment as produced by the lack of available, yet demanded, memory.

When to Reevaluate Memory Allocation?

You may need to increase or adjust memory allocation when:

Replication regularly enters PAUSED states or hangs under load.
Paging or swapping becomes a consistent pattern during peak workload.
Your application servers (e.g., SQL Server) frequently consume most of the available RAM.
The cluster experiences intermittent failovers with no underlying hardware failures.
You are operating in a cloud or virtual environment where host contention is possible.
You see “Resource Exhaustion” event logging from your system
Unexpected terminations of critical services

In HA environments, memory isn’t just for performance; it helps ensure predictable failover behavior and prevents cascading service interruptions.

Why Proper Memory Allocation Is Key to HA Reliability

Memory pressure can negatively affect nearly every layer of an HA environment, from replication drivers to application performance and failover timing. Proper memory allocation helps ensure predictable performance, stable cluster communication, and reliable recovery when a failover occurs. By proactively monitoring and planning memory usage, organizations can avoid unnecessary downtime and maintain the high availability their systems demand. If memory allocation challenges are impacting HA performance or failover behavior, request a SIOS demo to see how we can help strengthen reliability.

Author: Aidan Macklen, Associate Product Support Specialist at SIOS Technology Corp.

Reproduced with permission from SIOS