diff --git a/src/fdb5/CMakeLists.txt b/src/fdb5/CMakeLists.txt
index 6b494bb29..41f61c69b 100644
--- a/src/fdb5/CMakeLists.txt
+++ b/src/fdb5/CMakeLists.txt
@@ -48,7 +48,7 @@ list( APPEND fdb5_srcs
     api/helpers/PurgeIterator.h
     api/helpers/StatsIterator.cc
     api/helpers/StatsIterator.h
-    api/helpers/ArchiveCallback.h
+    api/helpers/Callback.h
 
     api/local/QueryVisitor.h
     api/local/QueueStringLogTarget.h
diff --git a/src/fdb5/LibFdb5.cc b/src/fdb5/LibFdb5.cc
index ec688c31e..161f3c407 100644
--- a/src/fdb5/LibFdb5.cc
+++ b/src/fdb5/LibFdb5.cc
@@ -48,6 +48,14 @@ const Config& LibFdb5::defaultConfig(const eckit::Configuration& userConfig) {
     return *config_;
 }
 
+ConstructorCallback LibFdb5::constructorCallback() {
+    return constructorCallback_;
+}
+
+void LibFdb5::registerConstructorCallback(ConstructorCallback cb) {
+    constructorCallback_ = cb;
+}
+
 bool LibFdb5::dontDeregisterFactories() const {
 #if eckit_VERSION_MAJOR > 1 || (eckit_VERSION_MAJOR == 1 && (eckit_VERSION_MINOR > 17 || (eckit_VERSION_MINOR == 17 && eckit_VERSION_PATCH >0)))
     return eckit::LibEcKit::instance().dontDeregisterFactories();
diff --git a/src/fdb5/LibFdb5.h b/src/fdb5/LibFdb5.h
index 524c93b9c..2e1020a5d 100644
--- a/src/fdb5/LibFdb5.h
+++ b/src/fdb5/LibFdb5.h
@@ -21,6 +21,7 @@
 
 #include "fdb5/database/DB.h"
 #include "fdb5/types/TypesRegistry.h"
+#include "fdb5/api/helpers/Callback.h"
 
 namespace fdb5 {
 
@@ -75,6 +76,10 @@ class LibFdb5 : public eckit::system::Library {
 
     bool dontDeregisterFactories() const;
 
+    void registerConstructorCallback(ConstructorCallback cb);
+
+    ConstructorCallback constructorCallback();
+
 protected:
     virtual std::string version() const;
 
@@ -82,6 +87,7 @@ class LibFdb5 : public eckit::system::Library {
 
 private:
     std::unique_ptr<Config> config_;
+    ConstructorCallback constructorCallback_ = CALLBACK_CONSTRUCTOR_NOOP;
 };
 
 //----------------------------------------------------------------------------------------------------------------------
diff --git a/src/fdb5/api/FDB.cc b/src/fdb5/api/FDB.cc
index 84a302225..4ae6edc0f 100644
--- a/src/fdb5/api/FDB.cc
+++ b/src/fdb5/api/FDB.cc
@@ -20,6 +20,9 @@
 #include "eckit/message/Message.h"
 #include "eckit/message/Reader.h"
 
+#include "eckit/system/Plugin.h"
+#include "eckit/system/LibraryManager.h"
+
 #include "metkit/hypercube/HyperCubePayloaded.h"
 
 #include "fdb5/LibFdb5.h"
@@ -38,7 +41,10 @@ namespace fdb5 {
 FDB::FDB(const Config &config) :
     internal_(FDBFactory::instance().build(config)),
     dirty_(false),
-    reportStats_(config.getBool("statistics", false)) {}
+    reportStats_(config.getBool("statistics", false)) {
+    eckit::system::LibraryManager::autoLoadPlugins({});
+    LibFdb5::instance().constructorCallback()(*this);
+}
 
 
 FDB::~FDB() {
@@ -283,11 +289,11 @@ void FDB::print(std::ostream& s) const {
 
 void FDB::flush() {
     if (dirty_) {
-
         eckit::Timer timer;
         timer.start();
 
         internal_->flush();
+        flushCallback_();
         dirty_ = false;
 
         timer.stop();
@@ -321,8 +327,12 @@ bool FDB::enabled(const ControlIdentifier& controlIdentifier) const {
     return internal_->enabled(controlIdentifier);
 }
 
-void FDB::registerCallback(ArchiveCallback callback) {
-    internal_->registerCallback(callback);
+void FDB::registerArchiveCallback(ArchiveCallback callback) { // todo rename
+    internal_->registerArchiveCallback(callback);
+}
+
+void FDB::registerFlushCallback(FlushCallback callback) { // todo rename
+    flushCallback_ = callback;
 }
 
 //----------------------------------------------------------------------------------------------------------------------
diff --git a/src/fdb5/api/FDB.h b/src/fdb5/api/FDB.h
index 69794859d..6be852565 100644
--- a/src/fdb5/api/FDB.h
+++ b/src/fdb5/api/FDB.h
@@ -34,7 +34,7 @@
 #include "fdb5/api/helpers/WipeIterator.h"
 #include "fdb5/api/helpers/MoveIterator.h"
 #include "fdb5/config/Config.h"
-#include "fdb5/api/helpers/ArchiveCallback.h"
+#include "fdb5/api/helpers/Callback.h"
 
 namespace eckit {
 namespace message {
@@ -119,7 +119,8 @@ class FDB {
 
     bool dirty() const;
 
-    void registerCallback(ArchiveCallback callback);
+    void registerArchiveCallback(ArchiveCallback callback);
+    void registerFlushCallback(FlushCallback callback);
 
     // -------------- API management ----------------------------
 
@@ -155,6 +156,7 @@ class FDB {
 
     FDBStats stats_;
 
+    FlushCallback flushCallback_ = CALLBACK_FLUSH_NOOP;
 };
 
 //----------------------------------------------------------------------------------------------------------------------
diff --git a/src/fdb5/api/FDBFactory.h b/src/fdb5/api/FDBFactory.h
index ed526421b..6cd3c1c37 100644
--- a/src/fdb5/api/FDBFactory.h
+++ b/src/fdb5/api/FDBFactory.h
@@ -37,7 +37,7 @@
 #include "fdb5/api/helpers/PurgeIterator.h"
 #include "fdb5/api/helpers/StatsIterator.h"
 #include "fdb5/api/helpers/StatusIterator.h"
-#include "fdb5/api/helpers/ArchiveCallback.h"
+#include "fdb5/api/helpers/Callback.h"
 
 namespace eckit {
 namespace message {
@@ -91,7 +91,7 @@ class FDBBase : private eckit::NonCopyable {
 
     virtual AxesIterator axes(const FDBToolRequest& request, int axes) { NOTIMP; }
 
-    void registerCallback(ArchiveCallback callback) {callback_ = callback;}
+    void registerArchiveCallback(ArchiveCallback callback) {callback_ = callback;}
 
     // -------------- API management ----------------------------
 
diff --git a/src/fdb5/api/helpers/ArchiveCallback.h b/src/fdb5/api/helpers/Callback.h
similarity index 54%
rename from src/fdb5/api/helpers/ArchiveCallback.h
rename to src/fdb5/api/helpers/Callback.h
index a98dc894a..8b9f04409 100644
--- a/src/fdb5/api/helpers/ArchiveCallback.h
+++ b/src/fdb5/api/helpers/Callback.h
@@ -14,14 +14,20 @@
  */
 
 #pragma once
-
+#include <future>
 #include "fdb5/database/Key.h"
 #include "fdb5/database/FieldLocation.h"
 
 namespace fdb5 {
 
-using ArchiveCallback = std::function<void(const Key&, const FieldLocation&)>;
+class FDB;
+
+using ArchiveCallback = std::function<void(const Key& key, const void* data, size_t length, std::future<std::shared_ptr<FieldLocation>>)>;
+using FlushCallback = std::function<void()>;
+using ConstructorCallback = std::function<void(FDB&)>;
 
-static const ArchiveCallback CALLBACK_NOOP = [](const Key&, const FieldLocation&) {};
+static const ArchiveCallback CALLBACK_NOOP = [](const Key& key, const void* data, size_t length, std::future<std::shared_ptr<FieldLocation>>) {};
+static const FlushCallback CALLBACK_FLUSH_NOOP = []() {};
+static const ConstructorCallback CALLBACK_CONSTRUCTOR_NOOP = [](FDB&) {};
 
 } // namespace fdb5
diff --git a/src/fdb5/daos/DaosCatalogueWriter.cc b/src/fdb5/daos/DaosCatalogueWriter.cc
index 3a9f0b661..fc3927f9c 100644
--- a/src/fdb5/daos/DaosCatalogueWriter.cc
+++ b/src/fdb5/daos/DaosCatalogueWriter.cc
@@ -226,7 +226,7 @@ const Index& DaosCatalogueWriter::currentIndex() {
 /// @todo: other writers may be simultaneously updating the axes KeyValues in DAOS. Should these
 ///        new updates be retrieved and put into in-memory axes from time to time, e.g. every
 ///        time a value is put in an axis KeyValue?
-void DaosCatalogueWriter::archive(const Key& key, std::unique_ptr<FieldLocation> fieldLocation) {
+void DaosCatalogueWriter::archive(const Key& key, std::shared_ptr<FieldLocation> fieldLocation) {
 
     if (current_.null()) {
         ASSERT(!currentIndexKey_.empty());
diff --git a/src/fdb5/daos/DaosCatalogueWriter.h b/src/fdb5/daos/DaosCatalogueWriter.h
index b738a6420..44fcd7384 100644
--- a/src/fdb5/daos/DaosCatalogueWriter.h
+++ b/src/fdb5/daos/DaosCatalogueWriter.h
@@ -56,7 +56,7 @@ class DaosCatalogueWriter : public DaosCatalogue, public CatalogueWriter {
     void clean() override;
     void close() override;
 
-    void archive(const Key& key, std::unique_ptr<FieldLocation> fieldLocation) override;
+    void archive(const Key& key, std::shared_ptr<FieldLocation> fieldLocation) override;
 
     virtual void print( std::ostream &out ) const override { NOTIMP; }
 
diff --git a/src/fdb5/database/Catalogue.h b/src/fdb5/database/Catalogue.h
index 1d7be79fc..c2b344701 100644
--- a/src/fdb5/database/Catalogue.h
+++ b/src/fdb5/database/Catalogue.h
@@ -121,7 +121,7 @@ class CatalogueReader {
 class CatalogueWriter {
 public:
     virtual const Index& currentIndex() = 0;
-    virtual void archive(const Key& key, std::unique_ptr<FieldLocation> fieldLocation) = 0;
+    virtual void archive(const Key& key, std::shared_ptr<FieldLocation> fieldLocation) = 0;
     virtual void overlayDB(const Catalogue& otherCatalogue, const std::set<std::string>& variableKeys, bool unmount) = 0;
     virtual void index(const Key& key, const eckit::URI& uri, eckit::Offset offset, eckit::Length length) = 0;
     virtual void reconsolidate() = 0;
diff --git a/src/fdb5/database/DB.cc b/src/fdb5/database/DB.cc
index 56d5c2a3c..b916612f1 100644
--- a/src/fdb5/database/DB.cc
+++ b/src/fdb5/database/DB.cc
@@ -14,7 +14,6 @@
 #include "fdb5/database/DB.h"
 #include "fdb5/database/Field.h"
 #include "fdb5/toc/TocEngine.h"
-#include "fdb5/api/helpers/ArchiveCallback.h"
 
 using eckit::Log;
 
@@ -110,9 +109,14 @@ void DB::archive(const Key& key, const void* data, eckit::Length length, const K
     ASSERT(cat);
 
     const Index& idx = cat->currentIndex();
-    std::unique_ptr<FieldLocation> location(store().archive(idx.key(), data, length));
 
-    callback(field, *location);
+    std::shared_ptr<FieldLocation> location(store().archive(idx.key(), data, length));
+
+    // In anticipaton of store().archive() working asynchronously in later FDB versions.
+    std::promise<std::shared_ptr<FieldLocation>> promise;
+    promise.set_value(location);
+
+    callback(field, data, length, promise.get_future());
 
     cat->archive(key, std::move(location));
 }
diff --git a/src/fdb5/database/DB.h b/src/fdb5/database/DB.h
index fcb6735c1..ee80a826f 100644
--- a/src/fdb5/database/DB.h
+++ b/src/fdb5/database/DB.h
@@ -23,7 +23,7 @@
 #include "fdb5/database/EntryVisitMechanism.h"
 #include "fdb5/database/Key.h"
 #include "fdb5/database/Store.h"
-#include "fdb5/api/helpers/ArchiveCallback.h"
+#include "fdb5/api/helpers/Callback.h"
 
 namespace eckit {
 class DataHandle;
diff --git a/src/fdb5/database/Field.cc b/src/fdb5/database/Field.cc
index 53d3a7be9..a29dd3b60 100644
--- a/src/fdb5/database/Field.cc
+++ b/src/fdb5/database/Field.cc
@@ -16,7 +16,7 @@ namespace fdb5 {
 
 Field::Field() {}
 
-Field::Field(std::unique_ptr<FieldLocation> location, time_t timestamp, const FieldDetails& details):
+Field::Field(std::shared_ptr<FieldLocation> location, time_t timestamp, const FieldDetails& details):
     location_(std::move(location)),
     timestamp_(timestamp),
     details_(details) {
diff --git a/src/fdb5/database/Field.h b/src/fdb5/database/Field.h
index b49ef3753..4ce77a3e3 100644
--- a/src/fdb5/database/Field.h
+++ b/src/fdb5/database/Field.h
@@ -43,7 +43,7 @@ class Field {
 
     Field();
 
-    Field(std::unique_ptr<FieldLocation> location, time_t timestamp, const FieldDetails& details = FieldDetails());
+    Field(std::shared_ptr<FieldLocation> location, time_t timestamp, const FieldDetails& details = FieldDetails());
     Field(const FieldLocation&& location, time_t timestamp, const FieldDetails& details = FieldDetails());
 
     eckit::DataHandle* dataHandle() const { return location_->dataHandle(); }
diff --git a/src/fdb5/toc/TocCatalogueWriter.cc b/src/fdb5/toc/TocCatalogueWriter.cc
index 8bf0f8078..feea5c9aa 100644
--- a/src/fdb5/toc/TocCatalogueWriter.cc
+++ b/src/fdb5/toc/TocCatalogueWriter.cc
@@ -294,7 +294,7 @@ bool TocCatalogueWriter::enabled(const ControlIdentifier& controlIdentifier) con
     return TocCatalogue::enabled(controlIdentifier);
 }
 
-void TocCatalogueWriter::archive(const Key& key, std::unique_ptr<FieldLocation> fieldLocation) {
+void TocCatalogueWriter::archive(const Key& key, std::shared_ptr<FieldLocation> fieldLocation) {
     dirty_ = true;
 
     if (current_.null()) {
diff --git a/src/fdb5/toc/TocCatalogueWriter.h b/src/fdb5/toc/TocCatalogueWriter.h
index 2d2caa88f..040799e43 100644
--- a/src/fdb5/toc/TocCatalogueWriter.h
+++ b/src/fdb5/toc/TocCatalogueWriter.h
@@ -70,7 +70,7 @@ class TocCatalogueWriter : public TocCatalogue, public CatalogueWriter {
     void clean() override;
     void close() override;
 
-    void archive(const Key& key, std::unique_ptr<FieldLocation> fieldLocation) override;
+    void archive(const Key& key, std::shared_ptr<FieldLocation> fieldLocation) override;
     void reconsolidateIndexesAndTocs();
 
     virtual void print( std::ostream &out ) const override;
diff --git a/tests/fdb/api/CMakeLists.txt b/tests/fdb/api/CMakeLists.txt
index cf631cdbd..a61a69aa0 100644
--- a/tests/fdb/api/CMakeLists.txt
+++ b/tests/fdb/api/CMakeLists.txt
@@ -27,7 +27,7 @@ list( APPEND api_tests
     select
     dist
     fdb_c
-    archive_callback
+    callback
 )
 
 foreach( _test ${api_tests} )
diff --git a/tests/fdb/api/test_archive_callback.cc b/tests/fdb/api/test_callback.cc
similarity index 80%
rename from tests/fdb/api/test_archive_callback.cc
rename to tests/fdb/api/test_callback.cc
index ced87fa5b..60449c883 100644
--- a/tests/fdb/api/test_archive_callback.cc
+++ b/tests/fdb/api/test_callback.cc
@@ -4,7 +4,7 @@
 namespace fdb5::test {
 
 //----------------------------------------------------------------------------------------------------------------------
-CASE("Archive callback") {
+CASE("Archive and flush callback") {
     FDB fdb;
 
     std::string data_str = "Raining cats and dogs";
@@ -24,9 +24,15 @@ CASE("Archive callback") {
 
     std::map<fdb5::Key, eckit::URI> map;
     std::vector<Key> keys;
+    bool flushCalled = false;
 
-    fdb.registerCallback([&map] (const fdb5::Key& key, const fdb5::FieldLocation& location) {
-        map[key] = location.fullUri();
+    fdb.registerArchiveCallback([&map] (const Key& key, const void* data, size_t length, std::future<std::shared_ptr<FieldLocation>> future) {
+        std::shared_ptr<FieldLocation> location = future.get();
+        map[key] = location->fullUri();
+    });
+
+    fdb.registerFlushCallback([&flushCalled] () {
+        flushCalled = true;
     });
 
     key.set("step","1");
@@ -43,6 +49,8 @@ CASE("Archive callback") {
     
     fdb.flush();
 
+    EXPECT(flushCalled);
+
     EXPECT(map.size() == 3);
 
     // for (const auto& [key, uri] : map) {