--- canonical: "https://safekit.eviden.com/products/high-availability-software-for-application-clustering/byte-level-file-replication-vs-block-level-disk-replication/" llms_index: "https://safekit.eviden.com/llms.txt" llms_section: "Competitive Positioning" topics: "Byte-Level File Replication vs. Block-Level Disk Replication for HA, SafeKit Proposes a SANless Architecture Using Byte-Level File Replication, Byte-level file replication vs block-level disk replication in a high availability cluster, Pros and cons of byte-level file replication vs block-level disk replication, 🔍 SafeKit High Availability Navigation Hub" --- # Byte-Level File Replication vs. Block-Level Disk Replication for HA ## SafeKit Proposes a SANless Architecture Using Byte-Level File Replication [🧑 Contact us](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/contact-us-for-safekit/) [🎁 SafeKit free trial](https://safekit.eviden.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.eviden.com/products/high-availability-software-for-application-clustering/get-a-quote-safekit-en/) ## Byte-level file replication vs block-level disk replication in a high availability cluster ### Overview This article explores the pros and cons of byte-level file replication vs block-level disk replication in a high availability cluster. We are looking at volume of replicated data, impact on application data organization, recovery time, simplicity of implementation. ![Byte-level file replication vs block-level disk replication](data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20200%20110'%3E%3C/svg%3E)![Byte-level file replication vs block-level disk replication](https://safekit.eviden.com/wp-content/uploads/2023/02/file-replication-vs-disk-replication.png) The following comparative tables explain in detail the byte-level file replication implemented by SafeKit, a high availability software product. ### What is byte-level file replication? Byte-level file replication (like with [SafeKit](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/)) means that only modifications inside files are replicated. [Synchronous replication](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/synchronous-replication-vs-asynchronous-replication/) is required in a high vailability cluster for having 0 data loss in case of failure. Asynchronous replication is for backup solutions. The volume of replicated data is reduced to information modified by applications inside their files. No extra data is replicated. There is no impact on data organization for an application. For instance, if an application has its data in the system disk, byte-level file replication is working. Recovery time (RTO) in the event of a failover is reduced to the application restart time on the secondary server's replicated files. Finally, the solution is very simple to configure as only the paths of directories to replicate are configured. ### What is block-level disk replication? Block-level disk replication (like with [DRBD](https://linbit.com/drbd/)) means that only modifications inside a disk are replicated. The volume of replicated data is not reduced to information modified by applications. Extra data are replicated like the meta data for managing the disk (list of free blocks, file system internal information). There is a strong impact on the organization of application data. All data must be localized in the replicated disk. At least, it requires an application reconfiguration. Or, it is impossible if some data to replicate are in the system disk, because this disk must remain specific to each server. The recovery time (RTO) increases with the file system recovery procedure on the replicated disk after a failover. Finally, the solution is not easy to configure because skills are required to configure a special disk with a file system. Additionally, application skills are required to configure application data in the replicated disk. ## Pros and cons of byte-level file replication vs block-level disk replication | | | | --- | --- | | **Cluster with byte-level file replication** Cluster with byte-level file replicationCluster with byte-level file replication | **Cluster with block-level disk replication** Cluster with block-level disk replicationCluster with block-level disk replication | | **Product** | | | [SafeKit on Windows and Linux](/high-availability-software-for-application-clustering/) | Disks replication products as [DRBD](https://linbit.com/drbd/) | | **Application data organization** | | | 0 impact on application data organization with SafeKit. [Just define directories to replicate in real-time](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/file-replication-byte-level-with-failover-mirror-cluster/). Even directories inside the system disk can be replicated. | Impact on application data organization. Special configuration of the application to put its data in a replicated disk. Data in the system disk cannot be replicated. | | **Data replication** | | | Synchronous byte-level file replication. Replicates file modification operations generated by application activity **No meta data** are replicated. Only data modified in files are replicated, not entire files (byte-level file replication). [Synchronous replication to avoid data loss on failure](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/synchronous-replication-vs-asynchronous-replication/). | Replicate all data modified inside a replicated disk. Application data plus **meta data** are replicated. For instance, last access time on a file is replicated (last access time is modified each time the file is read). | | **Complexity of deployment** | | | No - install a software on 2 servers | Yes - require specific IT skills to configure OS and replicated disk | | **Failover** | | | Just restart the application on the second server. | Remount the file system on the replicated disk. Pass the recovery procedure on the file system. And then restart the application. | | **Failback** | | | Automatic failback. Resynchronization of data on the secondary server without stopping the application on the primary server. No application failover while data are not resynchronized. | All products are not at the same level of features. | | **Quorum and split brain** | | | Application executed on a single server after a network isolation (split brain). Coherency of data after a split brain. No need for a third machine or a quorum disk or a special heartbeat line for split brain. [More information on heartbeat, failover and quorum](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/heartbeat-failover-quorum-windows-linux-aix-cluster/) | Require a special quorum disk or a third quorum server to manage split brain. | | **Suited for** | | | [Software editors which want to add a simple high availability option to their application](https://safekit.eviden.com/products/high-availability-software-for-application-clustering/application-clustering-software/) | Enterprise with IT skills in clustering. | ## 🔍 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.eviden.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 (OEM Software, Edge Servers, SCADA, and more)](https://safekit.eviden.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.eviden.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.eviden.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.eviden.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.eviden.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.eviden.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.eviden.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.eviden.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.eviden.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.eviden.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.eviden.com/products/high-availability-software-for-application-clustering/contact-us-for-safekit/) [🎁 SafeKit free trial](https://safekit.eviden.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.eviden.com/products/high-availability-software-for-application-clustering/get-a-quote-safekit-en/)