diff --git a/cpp_src/cmd/reindexer_server/test/test_storage_compatibility.sh b/cpp_src/cmd/reindexer_server/test/test_storage_compatibility.sh
new file mode 100755
index 000000000..d189d3841
--- /dev/null
+++ b/cpp_src/cmd/reindexer_server/test/test_storage_compatibility.sh
@@ -0,0 +1,195 @@
+#!/bin/bash
+# Task: https://github.com/restream/reindexer/-/issues/1188
+set -e
+
+function KillAndRemoveServer {
+	local pid=$1
+	kill $pid
+	wait $pid
+	yum remove -y 'reindexer*' > /dev/null
+}
+
+function WaitForDB {
+	# wait until DB is loaded
+	set +e # disable "exit on error" so the script won't stop when DB's not loaded yet
+	is_connected=$(reindexer_tool --dsn $ADDRESS --command '\databases list');
+	while [[ $is_connected != "test" ]]
+		do
+			sleep 2
+			is_connected=$(reindexer_tool --dsn $ADDRESS --command '\databases list');
+		done
+	set -e
+}
+
+function CompareNamespacesLists {
+	local ns_list_actual=$1
+	local ns_list_expected=$2
+	local pid=$3
+
+	diff=$(echo ${ns_list_actual[@]} ${ns_list_expected[@]} | tr ' ' '\n' | sort | uniq -u) # compare in any order
+	if [ "$diff" == "" ]; then
+	    echo "## PASS: namespaces list not changed"
+	else
+	    echo "##### FAIL: namespaces list was changed"
+	    echo "expected: $ns_list_expected"
+	    echo "actual: $ns_list_actual"
+		KillAndRemoveServer $pid;
+	    exit 1
+    fi
+}
+
+function CompareMemstats {
+	local actual=$1
+	local expected=$2
+	local pid=$3
+	diff=$(echo ${actual[@]} ${expected[@]} | tr ' ' '\n' | sed 's/\(.*\),$/\1/' | sort | uniq -u) # compare in any order
+	if [ "$diff" == "" ]; then
+	    echo "## PASS: memstats not changed"
+	else
+	    echo "##### FAIL: memstats was changed"
+	    echo "expected: $expected"
+	    echo "actual: $actual"
+		KillAndRemoveServer $pid;
+	    exit 1
+    fi
+}
+
+
+RX_SERVER_CURRENT_VERSION_RPM="$(basename build/reindexer-*server*.rpm)"
+VERSION_FROM_RPM=$(echo "$RX_SERVER_CURRENT_VERSION_RPM" | grep -o '.*server-..')
+VERSION=$(echo ${VERSION_FROM_RPM: -2:1})   # one-digit version
+
+echo "## choose latest release rpm file"
+if [ $VERSION == 3 ]; then
+  LATEST_RELEASE=$(python3 cpp_src/cmd/reindexer_server/test/get_last_rx_version.py -v 3)
+  namespaces_list_expected=$'purchase_options_ext_dict\nchild_account_recommendations\n#config\n#activitystats\nradio_channels\ncollections\n#namespaces\nwp_imports_tasks\nepg_genres\nrecom_media_items_personal\nrecom_epg_archive_default\n#perfstats\nrecom_epg_live_default\nmedia_view_templates\nasset_video_servers\nwp_tasks_schedule\nadmin_roles\n#clientsstats\nrecom_epg_archive_personal\nrecom_media_items_similars\nmenu_items\naccount_recommendations\nkaraoke_items\nmedia_items\nbanners\n#queriesperfstats\nrecom_media_items_default\nrecom_epg_live_personal\nservices\n#memstats\nchannels\nmedia_item_recommendations\nwp_tasks_tasks\nepg'
+elif [ $VERSION == 4 ]; then
+  LATEST_RELEASE=$(python3 cpp_src/cmd/reindexer_server/test/get_last_rx_version.py -v 4)
+  # replicationstats ns added for v4
+  namespaces_list_expected=$'purchase_options_ext_dict\nchild_account_recommendations\n#config\n#activitystats\n#replicationstats\nradio_channels\ncollections\n#namespaces\nwp_imports_tasks\nepg_genres\nrecom_media_items_personal\nrecom_epg_archive_default\n#perfstats\nrecom_epg_live_default\nmedia_view_templates\nasset_video_servers\nwp_tasks_schedule\nadmin_roles\n#clientsstats\nrecom_epg_archive_personal\nrecom_media_items_similars\nmenu_items\naccount_recommendations\nkaraoke_items\nmedia_items\nbanners\n#queriesperfstats\nrecom_media_items_default\nrecom_epg_live_personal\nservices\n#memstats\nchannels\nmedia_item_recommendations\nwp_tasks_tasks\nepg'
+else
+  echo "Unknown version"
+  exit 1
+fi
+
+echo "## downloading latest release rpm file: $LATEST_RELEASE"
+curl "http://repo.itv.restr.im/itv-api-ng/7/x86_64/$LATEST_RELEASE" --output $LATEST_RELEASE;
+echo "## downloading example DB"
+curl "https://git.restream.ru/MaksimKravchuk/reindexer_testdata/-/raw/master/big.zip" --output big.zip;
+unzip -o big.zip # unzips into mydb_big.rxdump;
+
+ADDRESS="cproto://127.0.0.1:6534/"
+DB_NAME="test"
+
+memstats_expected=$'[
+{"replication":{"data_hash":24651210926,"data_count":3}},
+{"replication":{"data_hash":6252344969,"data_count":1}},
+{"replication":{"data_hash":37734732881,"data_count":28}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":1024095024522,"data_count":1145}},
+{"replication":{"data_hash":8373644068,"data_count":1315}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":7404222244,"data_count":97}},
+{"replication":{"data_hash":94132837196,"data_count":4}},
+{"replication":{"data_hash":1896088071,"data_count":2}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":-672103903,"data_count":33538}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":6833710705,"data_count":1}},
+{"replication":{"data_hash":5858155773472,"data_count":4500}},
+{"replication":{"data_hash":-473221280268823592,"data_count":65448}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":8288213744,"data_count":3}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":0,"data_count":0}},
+{"replication":{"data_hash":354171024786967,"data_count":3941}},
+{"replication":{"data_hash":-6520334670,"data_count":35886}},
+{"replication":{"data_hash":112772074632,"data_count":281}},
+{"replication":{"data_hash":-12679568198538,"data_count":1623116}}
+]
+Returned 27 rows'
+
+echo "##### Forward compatibility test #####"
+
+DB_PATH=$(pwd)"/rx_db"
+
+echo "Database: "$DB_PATH
+
+echo "## installing latest release: $LATEST_RELEASE"
+yum install -y $LATEST_RELEASE > /dev/null;
+# run RX server with disabled logging
+reindexer_server -l warning --httplog=none --rpclog=none --db $DB_PATH &
+server_pid=$!
+sleep 2;
+
+reindexer_tool --dsn $ADDRESS$DB_NAME -f mydb_big.rxdump --createdb;
+sleep 1;
+
+namespaces_1=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command '\namespaces list');
+echo $namespaces_1;
+CompareNamespacesLists "${namespaces_1[@]}" "${namespaces_list_expected[@]}" $server_pid;
+
+memstats_1=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command 'select replication.data_hash, replication.data_count from #memstats');
+CompareMemstats "${memstats_1[@]}" "${memstats_expected[@]}" $server_pid;
+
+KillAndRemoveServer $server_pid;
+
+echo "## installing current version: $RX_SERVER_CURRENT_VERSION_RPM"
+yum install -y build/*.rpm > /dev/null;
+reindexer_server -l0  --corelog=none --httplog=none --rpclog=none --db $DB_PATH &
+server_pid=$!
+sleep 2;
+
+WaitForDB
+
+namespaces_2=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command '\namespaces list');
+echo $namespaces_2;
+CompareNamespacesLists "${namespaces_2[@]}" "${namespaces_1[@]}" $server_pid;
+
+memstats_2=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command 'select replication.data_hash, replication.data_count from #memstats');
+CompareMemstats "${memstats_2[@]}" "${memstats_1[@]}" $server_pid;
+
+KillAndRemoveServer $server_pid;
+rm -rf $DB_PATH;
+sleep 1;
+
+echo "##### Backward compatibility test #####"
+
+echo "## installing current version: $RX_SERVER_CURRENT_VERSION_RPM"
+yum install -y build/*.rpm > /dev/null;
+reindexer_server -l warning --httplog=none --rpclog=none --db $DB_PATH &
+server_pid=$!
+sleep 2;
+
+reindexer_tool --dsn $ADDRESS$DB_NAME -f mydb_big.rxdump --createdb;
+sleep 1;
+
+namespaces_3=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command '\namespaces list');
+echo $namespaces_3;
+CompareNamespacesLists "${namespaces_3[@]}" "${namespaces_list_expected[@]}" $server_pid;
+
+memstats_3=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command 'select replication.data_hash, replication.data_count from #memstats');
+CompareMemstats "${memstats_3[@]}" "${memstats_expected[@]}" $server_pid;
+
+KillAndRemoveServer $server_pid;
+
+echo "## installing latest release: $LATEST_RELEASE"
+yum install -y $LATEST_RELEASE > /dev/null;
+reindexer_server -l warning --httplog=none --rpclog=none --db $DB_PATH &
+server_pid=$!
+sleep 2;
+
+WaitForDB
+
+namespaces_4=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command '\namespaces list');
+echo $namespaces_4;
+CompareNamespacesLists "${namespaces_4[@]}" "${namespaces_3[@]}" $server_pid;
+
+memstats_4=$(reindexer_tool --dsn $ADDRESS$DB_NAME --command 'select replication.data_hash, replication.data_count from #memstats');
+CompareMemstats "${memstats_4[@]}" "${memstats_3[@]}" $server_pid;
+
+KillAndRemoveServer $server_pid;
+rm -rf $DB_PATH;
diff --git a/cpp_src/core/lsn.cc b/cpp_src/core/lsn.cc
index dc88fb059..73c0130e2 100644
--- a/cpp_src/core/lsn.cc
+++ b/cpp_src/core/lsn.cc
@@ -3,9 +3,11 @@
 
 namespace reindexer {
 
-void lsn_t::GetJSON(JsonBuilder &builder) const {
+void lsn_t::GetJSON(JsonBuilder& builder) const {
 	builder.Put("server_id", Server());
 	builder.Put("counter", Counter());
 }
 
-} // namespace reindexer
+[[noreturn]] void lsn_t::throwValidation(ErrorCode code, const char* fmt, int64_t value) { throw Error(code, fmt, value); }
+
+}  // namespace reindexer
\ No newline at end of file
diff --git a/cpp_src/core/lsn.h b/cpp_src/core/lsn.h
index eb1f83d15..174540da4 100644
--- a/cpp_src/core/lsn.h
+++ b/cpp_src/core/lsn.h
@@ -13,58 +13,53 @@ class JsonBuilder;
 // SSS        NNN NNN NNN NNN NNN (18 decimal digits)
 
 struct lsn_t {
-	static const int64_t digitCountLSNMult = 1000000000000000ll;
+private:
+	static constexpr int16_t kMinServerIDValue = 0;
+	static constexpr int16_t kMaxServerIDValue = 999;
 
-	static const int64_t kCounterbitCount = 48;
-	static const int64_t kCounterMask = (1ull << kCounterbitCount) - 1ull;
+	static constexpr int64_t kMaxCounter = 1000000000000000ll;
+	static constexpr int64_t kDefaultCounter = kMaxCounter - 1;
 
+public:
 	void GetJSON(JsonBuilder &builder) const;
 
 	void FromJSON(const gason::JsonNode &root) {
-		int server = root["server_id"].As<int>(0);
-		int64_t counter = root["counter"].As<int64_t>(digitCountLSNMult - 1ll);
+		const int server = root["server_id"].As<int>(0);
+		const int64_t counter = root["counter"].As<int64_t>(kDefaultCounter);
 		payload_ = int64_t(lsn_t(counter, server));
 	}
 
-	lsn_t() {}
-	explicit lsn_t(int64_t v) {
-		if ((v & kCounterMask) == kCounterMask)	 // init -1
-			payload_ = digitCountLSNMult - 1ll;
-		else {
-			payload_ = v;
-		}
-	}
-	lsn_t(int64_t counter, uint8_t server) {
-		if ((counter & kCounterMask) == kCounterMask) counter = digitCountLSNMult - 1ll;
-		int64_t s = server * digitCountLSNMult;
-		payload_ = s + counter;
+	lsn_t() noexcept = default;
+	lsn_t(const lsn_t &) noexcept = default;
+	lsn_t(lsn_t &&) noexcept = default;
+	lsn_t &operator=(const lsn_t &) noexcept = default;
+	lsn_t &operator=(lsn_t &&) noexcept = default;
+	explicit lsn_t(int64_t v) : lsn_t(v % kMaxCounter, v / kMaxCounter) {}
+	lsn_t(int64_t counter, int16_t server) {
+		validateCounter(counter);
+		validateServerId(server);
+		payload_ = server * kMaxCounter + counter;
 	}
 	explicit operator int64_t() const { return payload_; }
 
-	bool operator==(lsn_t o) { return payload_ == o.payload_; }
-	bool operator!=(lsn_t o) { return payload_ != o.payload_; }
+	bool operator==(lsn_t o) const noexcept { return payload_ == o.payload_; }
+	bool operator!=(lsn_t o) const noexcept { return payload_ != o.payload_; }
 
-	int64_t SetServer(short s) {
-		if (s > 999) throw Error(errLogic, "Server id > 999");
-		int64_t server = s * digitCountLSNMult;
-		int64_t serverOld = payload_ / digitCountLSNMult;
-		payload_ = payload_ - serverOld * digitCountLSNMult + server;
+	int64_t SetServer(short server) {
+		validateServerId(server);
+		payload_ = server * kMaxCounter + Counter();
 		return payload_;
 	}
-	int64_t SetCounter(int64_t c) {
-		if (c >= digitCountLSNMult) throw Error(errLogic, "LSN Counter > digitCountLSNMult");
-		int64_t server = payload_ / digitCountLSNMult;
-		payload_ = server * digitCountLSNMult + c;
+	int64_t SetCounter(int64_t counter) {
+		validateCounter(counter);
+		payload_ = Server() * kMaxCounter + counter;
 		return payload_;
 	}
-	int64_t Counter() const {
-		int64_t server = payload_ / digitCountLSNMult;
-		return payload_ - server * digitCountLSNMult;
-	}
-	short Server() const { return payload_ / digitCountLSNMult; }
-	bool isEmpty() const { return Counter() == digitCountLSNMult - 1ll; }
+	int64_t Counter() const noexcept { return payload_ % kMaxCounter; }
+	int16_t Server() const noexcept { return payload_ / kMaxCounter; }
+	bool isEmpty() const noexcept { return Counter() == kDefaultCounter; }
 
-	int compare(lsn_t o) {
+	int compare(lsn_t o) const {
 		if (Server() != o.Server()) throw Error(errLogic, "Compare lsn from different server");
 		if (Counter() < o.Counter())
 			return -1;
@@ -73,13 +68,28 @@ struct lsn_t {
 		return 0;
 	}
 
-	bool operator<(lsn_t o) { return compare(o) == -1; }
-	bool operator<=(lsn_t o) { return compare(o) <= 0; }
-	bool operator>(lsn_t o) { return compare(o) == 1; }
-	bool operator>=(lsn_t o) { return compare(o) >= 0; }
+	bool operator<(lsn_t o) const { return compare(o) == -1; }
+	bool operator<=(lsn_t o) const { return compare(o) <= 0; }
+	bool operator>(lsn_t o) const { return compare(o) == 1; }
+	bool operator>=(lsn_t o) const { return compare(o) >= 0; }
+
+private:
+	int64_t payload_ = kDefaultCounter;
+	static void validateServerId(int16_t server) {
+		if (server < kMinServerIDValue) {
+			throwValidation(errLogic, "Server id < %d", kMinServerIDValue);
+		}
+		if (server > kMaxServerIDValue) {
+			throwValidation(errLogic, "Server id > %d", kMaxServerIDValue);
+		}
+	}
+	static void validateCounter(int64_t counter) {
+		if (counter > kDefaultCounter) {
+			throwValidation(errLogic, "LSN Counter > Default LSN (%d)", kMaxCounter);
+		}
+	}
 
-protected:
-	int64_t payload_ = digitCountLSNMult - 1ll;
+	[[noreturn]] static void throwValidation(ErrorCode, const char *, int64_t);
 };
 
 struct LSNPair {