diff --git a/src/ScadaLink.CLI/Commands/DataConnectionCommands.cs b/src/ScadaLink.CLI/Commands/DataConnectionCommands.cs
index 723bf00..6ef8250 100644
--- a/src/ScadaLink.CLI/Commands/DataConnectionCommands.cs
+++ b/src/ScadaLink.CLI/Commands/DataConnectionCommands.cs
@@ -38,7 +38,7 @@ public static class DataConnectionCommands
         var idOption = new Option<int>("--id") { Description = "Data connection ID", Required = true };
         var nameOption = new Option<string>("--name") { Description = "Connection name", Required = true };
         var protocolOption = new Option<string>("--protocol") { Description = "Protocol", Required = true };
-        var configOption = new Option<string?>("--configuration") { Description = "Configuration JSON" };
+        var configOption = new Option<string?>("--configuration") { Description = "Primary configuration JSON" };
 
         var cmd = new Command("update") { Description = "Update a data connection" };
         cmd.Add(idOption);
@@ -77,7 +77,7 @@ public static class DataConnectionCommands
         var siteIdOption = new Option<int>("--site-id") { Description = "Site ID", Required = true };
         var nameOption = new Option<string>("--name") { Description = "Connection name", Required = true };
         var protocolOption = new Option<string>("--protocol") { Description = "Protocol (e.g. OpcUa)", Required = true };
-        var configOption = new Option<string?>("--configuration") { Description = "Connection configuration JSON" };
+        var configOption = new Option<string?>("--configuration") { Description = "Primary configuration JSON" };
 
         var cmd = new Command("create") { Description = "Create a new data connection" };
         cmd.Add(siteIdOption);
diff --git a/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnectionForm.razor b/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnectionForm.razor
index e5b1fb3..cfba6a5 100644
--- a/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnectionForm.razor
+++ b/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnectionForm.razor
@@ -100,7 +100,7 @@
                     _siteName = _sites.FirstOrDefault(s => s.Id == _formSiteId)?.Name ?? $"Site {_formSiteId}";
                     _formName = _editingConnection.Name;
                     _formProtocol = _editingConnection.Protocol;
-                    _formConfiguration = _editingConnection.Configuration;
+                    _formConfiguration = _editingConnection.PrimaryConfiguration;
                 }
             }
             catch (Exception ex)
@@ -124,14 +124,14 @@
             {
                 _editingConnection.Name = _formName.Trim();
                 _editingConnection.Protocol = _formProtocol;
-                _editingConnection.Configuration = _formConfiguration?.Trim();
+                _editingConnection.PrimaryConfiguration = _formConfiguration?.Trim();
                 await SiteRepository.UpdateDataConnectionAsync(_editingConnection);
             }
             else
             {
                 var conn = new DataConnection(_formName.Trim(), _formProtocol, _formSiteId)
                 {
-                    Configuration = _formConfiguration?.Trim()
+                    PrimaryConfiguration = _formConfiguration?.Trim()
                 };
                 await SiteRepository.AddDataConnectionAsync(conn);
             }
diff --git a/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnections.razor b/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnections.razor
index 90353f3..bca9d3b 100644
--- a/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnections.razor
+++ b/src/ScadaLink.CentralUI/Components/Pages/Admin/DataConnections.razor
@@ -50,7 +50,7 @@
                         <td>@conn.Name</td>
                         <td><span class="badge bg-secondary">@conn.Protocol</span></td>
                         <td>@(_siteLookup.GetValueOrDefault(conn.SiteId)?.Name ?? $"Site {conn.SiteId}")</td>
-                        <td class="text-muted small text-truncate" style="max-width: 300px;">@(conn.Configuration ?? "—")</td>
+                        <td class="text-muted small text-truncate" style="max-width: 300px;">@(conn.PrimaryConfiguration ?? "—")</td>
                         <td>
                             <button class="btn btn-outline-primary btn-sm py-0 px-1 me-1"
                                     @onclick='() => NavigationManager.NavigateTo($"/admin/data-connections/{conn.Id}/edit")'>Edit</button>
diff --git a/src/ScadaLink.Commons/Entities/Sites/DataConnection.cs b/src/ScadaLink.Commons/Entities/Sites/DataConnection.cs
index 16df869..7721435 100644
--- a/src/ScadaLink.Commons/Entities/Sites/DataConnection.cs
+++ b/src/ScadaLink.Commons/Entities/Sites/DataConnection.cs
@@ -6,7 +6,9 @@ public class DataConnection
     public int SiteId { get; set; }
     public string Name { get; set; }
     public string Protocol { get; set; }
-    public string? Configuration { get; set; }
+    public string? PrimaryConfiguration { get; set; }
+    public string? BackupConfiguration { get; set; }
+    public int FailoverRetryCount { get; set; } = 3;
 
     public DataConnection(string name, string protocol, int siteId)
     {
diff --git a/src/ScadaLink.Commons/Messages/Artifacts/DataConnectionArtifact.cs b/src/ScadaLink.Commons/Messages/Artifacts/DataConnectionArtifact.cs
index 514adc4..00187b4 100644
--- a/src/ScadaLink.Commons/Messages/Artifacts/DataConnectionArtifact.cs
+++ b/src/ScadaLink.Commons/Messages/Artifacts/DataConnectionArtifact.cs
@@ -3,4 +3,6 @@ namespace ScadaLink.Commons.Messages.Artifacts;
 public record DataConnectionArtifact(
     string Name,
     string Protocol,
-    string? ConfigurationJson);
+    string? PrimaryConfigurationJson,
+    string? BackupConfigurationJson,
+    int FailoverRetryCount = 3);
diff --git a/src/ScadaLink.Commons/Messages/Management/DataConnectionCommands.cs b/src/ScadaLink.Commons/Messages/Management/DataConnectionCommands.cs
index 1e33aab..7ea35ef 100644
--- a/src/ScadaLink.Commons/Messages/Management/DataConnectionCommands.cs
+++ b/src/ScadaLink.Commons/Messages/Management/DataConnectionCommands.cs
@@ -2,6 +2,6 @@ namespace ScadaLink.Commons.Messages.Management;
 
 public record ListDataConnectionsCommand(int? SiteId = null);
 public record GetDataConnectionCommand(int DataConnectionId);
-public record CreateDataConnectionCommand(int SiteId, string Name, string Protocol, string? Configuration);
-public record UpdateDataConnectionCommand(int DataConnectionId, string Name, string Protocol, string? Configuration);
+public record CreateDataConnectionCommand(int SiteId, string Name, string Protocol, string? PrimaryConfiguration);
+public record UpdateDataConnectionCommand(int DataConnectionId, string Name, string Protocol, string? PrimaryConfiguration);
 public record DeleteDataConnectionCommand(int DataConnectionId);
diff --git a/src/ScadaLink.ConfigurationDatabase/Configurations/SiteConfiguration.cs b/src/ScadaLink.ConfigurationDatabase/Configurations/SiteConfiguration.cs
index 66e4da0..abfe7bb 100644
--- a/src/ScadaLink.ConfigurationDatabase/Configurations/SiteConfiguration.cs
+++ b/src/ScadaLink.ConfigurationDatabase/Configurations/SiteConfiguration.cs
@@ -43,9 +43,16 @@ public class DataConnectionConfiguration : IEntityTypeConfiguration<DataConnecti
             .IsRequired()
             .HasMaxLength(50);
 
-        builder.Property(d => d.Configuration)
+        builder.Property(d => d.PrimaryConfiguration)
             .HasMaxLength(4000);
 
+        builder.Property(d => d.BackupConfiguration)
+            .HasMaxLength(4000);
+
+        builder.Property(d => d.FailoverRetryCount)
+            .IsRequired()
+            .HasDefaultValue(3);
+
         builder.HasOne<Site>()
             .WithMany()
             .HasForeignKey(d => d.SiteId)
diff --git a/src/ScadaLink.DeploymentManager/ArtifactDeploymentService.cs b/src/ScadaLink.DeploymentManager/ArtifactDeploymentService.cs
index a653a62..b622ce7 100644
--- a/src/ScadaLink.DeploymentManager/ArtifactDeploymentService.cs
+++ b/src/ScadaLink.DeploymentManager/ArtifactDeploymentService.cs
@@ -102,7 +102,7 @@ public class ArtifactDeploymentService
 
         // Map data connections
         var dataConnectionArtifacts = dataConnections.Select(dc =>
-            new DataConnectionArtifact(dc.Name, dc.Protocol, dc.Configuration)).ToList();
+            new DataConnectionArtifact(dc.Name, dc.Protocol, dc.PrimaryConfiguration, dc.BackupConfiguration, dc.FailoverRetryCount)).ToList();
 
         // Map SMTP configurations — use Host as the artifact name (matches SQLite PK on site)
         var smtpArtifacts = smtpConfigurations.Select(smtp =>
diff --git a/src/ScadaLink.ManagementService/ManagementActor.cs b/src/ScadaLink.ManagementService/ManagementActor.cs
index 34a04e4..435be26 100644
--- a/src/ScadaLink.ManagementService/ManagementActor.cs
+++ b/src/ScadaLink.ManagementService/ManagementActor.cs
@@ -689,7 +689,7 @@ public class ManagementActor : ReceiveActor
     private static async Task<object?> HandleCreateDataConnection(IServiceProvider sp, CreateDataConnectionCommand cmd, string user)
     {
         var repo = sp.GetRequiredService<ISiteRepository>();
-        var conn = new DataConnection(cmd.Name, cmd.Protocol, cmd.SiteId) { Configuration = cmd.Configuration };
+        var conn = new DataConnection(cmd.Name, cmd.Protocol, cmd.SiteId) { PrimaryConfiguration = cmd.PrimaryConfiguration };
         await repo.AddDataConnectionAsync(conn);
         await repo.SaveChangesAsync();
         await AuditAsync(sp, user, "Create", "DataConnection", conn.Id.ToString(), conn.Name, conn);
@@ -703,7 +703,7 @@ public class ManagementActor : ReceiveActor
             ?? throw new InvalidOperationException($"DataConnection with ID {cmd.DataConnectionId} not found.");
         conn.Name = cmd.Name;
         conn.Protocol = cmd.Protocol;
-        conn.Configuration = cmd.Configuration;
+        conn.PrimaryConfiguration = cmd.PrimaryConfiguration;
         await repo.UpdateDataConnectionAsync(conn);
         await repo.SaveChangesAsync();
         await AuditAsync(sp, user, "Update", "DataConnection", conn.Id.ToString(), conn.Name, conn);
diff --git a/src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs b/src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs
index d8513ac..40e2b1f 100644
--- a/src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs
+++ b/src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs
@@ -615,7 +615,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                     foreach (var dc in command.DataConnections)
                     {
                         await _storage.StoreDataConnectionDefinitionAsync(
-                            dc.Name, dc.Protocol, dc.ConfigurationJson);
+                            dc.Name, dc.Protocol, dc.PrimaryConfigurationJson);
                     }
                 }
 
diff --git a/src/ScadaLink.SiteRuntime/Actors/SiteReplicationActor.cs b/src/ScadaLink.SiteRuntime/Actors/SiteReplicationActor.cs
index ba3e736..1b79f26 100644
--- a/src/ScadaLink.SiteRuntime/Actors/SiteReplicationActor.cs
+++ b/src/ScadaLink.SiteRuntime/Actors/SiteReplicationActor.cs
@@ -185,7 +185,7 @@ public class SiteReplicationActor : ReceiveActor
 
                 if (command.DataConnections != null)
                     foreach (var dc in command.DataConnections)
-                        await _storage.StoreDataConnectionDefinitionAsync(dc.Name, dc.Protocol, dc.ConfigurationJson);
+                        await _storage.StoreDataConnectionDefinitionAsync(dc.Name, dc.Protocol, dc.PrimaryConfigurationJson);
 
                 if (command.SmtpConfigurations != null)
                     foreach (var smtp in command.SmtpConfigurations)
diff --git a/src/ScadaLink.TemplateEngine/Flattening/FlatteningService.cs b/src/ScadaLink.TemplateEngine/Flattening/FlatteningService.cs
index cad7615..7a2596c 100644
--- a/src/ScadaLink.TemplateEngine/Flattening/FlatteningService.cs
+++ b/src/ScadaLink.TemplateEngine/Flattening/FlatteningService.cs
@@ -90,7 +90,7 @@ public class FlatteningService
                         connections[attr.BoundDataConnectionName] = new ConnectionConfig
                         {
                             Protocol = conn.Protocol,
-                            ConfigurationJson = conn.Configuration
+                            ConfigurationJson = conn.PrimaryConfiguration
                         };
                     }
                 }
diff --git a/src/ScadaLink.TemplateEngine/Services/SiteService.cs b/src/ScadaLink.TemplateEngine/Services/SiteService.cs
index e1225a5..51cf7f7 100644
--- a/src/ScadaLink.TemplateEngine/Services/SiteService.cs
+++ b/src/ScadaLink.TemplateEngine/Services/SiteService.cs
@@ -104,7 +104,7 @@ public class SiteService
         if (string.IsNullOrWhiteSpace(protocol))
             return Result<DataConnection>.Failure("Protocol is required.");
 
-        var connection = new DataConnection(name, protocol, siteId) { Configuration = configuration };
+        var connection = new DataConnection(name, protocol, siteId) { PrimaryConfiguration = configuration };
         await _repository.AddDataConnectionAsync(connection, cancellationToken);
         await _repository.SaveChangesAsync(cancellationToken);
 
@@ -124,7 +124,7 @@ public class SiteService
 
         connection.Name = name;
         connection.Protocol = protocol;
-        connection.Configuration = configuration;
+        connection.PrimaryConfiguration = configuration;
         await _repository.UpdateDataConnectionAsync(connection, cancellationToken);
         await _repository.SaveChangesAsync(cancellationToken);
 
diff --git a/tests/ScadaLink.TemplateEngine.Tests/Flattening/FlatteningServiceTests.cs b/tests/ScadaLink.TemplateEngine.Tests/Flattening/FlatteningServiceTests.cs
index 32562c1..941e9cb 100644
--- a/tests/ScadaLink.TemplateEngine.Tests/Flattening/FlatteningServiceTests.cs
+++ b/tests/ScadaLink.TemplateEngine.Tests/Flattening/FlatteningServiceTests.cs
@@ -200,7 +200,7 @@ public class FlatteningServiceTests
 
         var connections = new Dictionary<int, DataConnection>
         {
-            [100] = new("OPC-Server1", "OpcUa", 1) { Id = 100, Configuration = "opc.tcp://localhost:4840" }
+            [100] = new("OPC-Server1", "OpcUa", 1) { Id = 100, PrimaryConfiguration = "opc.tcp://localhost:4840" }
         };
 
         var result = _sut.Flatten(