diff --git a/src/core/out.c b/src/core/out.c
index b55142e6906..3c0790f790f 100644
--- a/src/core/out.c
+++ b/src/core/out.c
@@ -29,6 +29,43 @@ static int Log_level;
 static FILE *Out_fp;
 static unsigned Log_alignment;
 
+#ifdef DEBUG
+static const enum core_log_level level_to_core_log_level[5] = {
+	[0] = CORE_LOG_DISABLED,
+	[1] = CORE_LOG_LEVEL_ERROR,
+	[2] = CORE_LOG_LEVEL_NOTICE,
+	[3] = CORE_LOG_LEVEL_INFO,
+	[4] = CORE_LOG_LEVEL_DEBUG,
+};
+
+static const int core_log_level_to_level[6] = {
+	[CORE_LOG_LEVEL_FATAL]		= 1,
+	[CORE_LOG_LEVEL_ERROR]		= 1,
+	[CORE_LOG_LEVEL_WARNING]	= 2,
+	[CORE_LOG_LEVEL_NOTICE]		= 2,
+	[CORE_LOG_LEVEL_INFO]		= 3,
+	[CORE_LOG_LEVEL_DEBUG]		= 4,
+};
+
+#define OUT_MAX_LEVEL 4
+
+static void
+out_legacy(void *context, enum core_log_level core_level, const char *file_name,
+	const int line_no, const char *function_name, const char *message)
+{
+	SUPPRESS_UNUSED(context);
+
+	int level;
+	if (core_level == CORE_LOG_LEVEL_ALWAYS) {
+		level = 1; /* traditionally used for this kind of messages */
+	} else {
+		level = core_log_level_to_level[core_level];
+	}
+
+	out_log(file_name, line_no, function_name, level, "%s", message);
+}
+#endif /* DEBUG */
+
 /*
  * out_init -- initialize the log
  *
@@ -54,12 +91,27 @@ out_init(const char *log_prefix, const char *log_level_var,
 #ifdef DEBUG
 	char *log_level;
 	char *log_file;
+	int log_level_cropped = 0;
+	int ret;
 
 	if ((log_level = os_getenv(log_level_var)) != NULL) {
 		Log_level = atoi(log_level);
 		if (Log_level < 0) {
 			Log_level = 0;
 		}
+		if (Log_level <= OUT_MAX_LEVEL) {
+			log_level_cropped = Log_level;
+		} else {
+			log_level_cropped = OUT_MAX_LEVEL;
+		}
+	}
+
+	if (log_level != NULL) {
+		ret = core_log_set_threshold(CORE_LOG_THRESHOLD,
+			level_to_core_log_level[log_level_cropped]);
+		if (ret) {
+			CORE_LOG_FATAL("Cannot set log threshold");
+		}
 	}
 
 	if ((log_file = os_getenv(log_file_var)) != NULL &&
@@ -86,6 +138,13 @@ out_init(const char *log_prefix, const char *log_level_var,
 			abort();
 		}
 	}
+
+	if (log_level != NULL || log_file != NULL) {
+		ret = core_log_set_function(out_legacy, NULL);
+		if (ret) {
+			CORE_LOG_FATAL("Cannot set legacy log function");
+		}
+	}
 #endif	/* DEBUG */
 
 	char *log_alignment = os_getenv("PMDK_LOG_ALIGN");
diff --git a/src/test/traces/TEST6 b/src/test/traces/TEST6
deleted file mode 100755
index 05da8876e43..00000000000
--- a/src/test/traces/TEST6
+++ /dev/null
@@ -1,23 +0,0 @@
-#!/usr/bin/env bash
-# SPDX-License-Identifier: BSD-3-Clause
-# Copyright 2014-2019, Intel Corporation
-
-#
-# src/test/traces/TEST6 -- unit test for traces
-#
-
-. ../unittest/unittest.sh
-
-require_test_type medium
-
-require_fs_type none
-require_build_type debug
-
-setup
-
-export UT_LOG_LEVEL=4
-expect_normal_exit ./traces$EXESUFFIX 2>redir_stderr$UNITTEST_NUM.log
-
-check
-
-pass
diff --git a/src/test/traces/custom_file0.log.match b/src/test/traces/custom_file0.log.match
index 9209b0590f2..a3733783de9 100644
--- a/src/test/traces/custom_file0.log.match
+++ b/src/test/traces/custom_file0.log.match
@@ -1,16 +1,16 @@
-$(*)
-$(*)
-$(*)
-$(OPT)$(*) compiled with support for Valgrind pmemcheck
-$(OPT)$(*) compiled with support for Valgrind helgrind
-$(OPT)$(*) compiled with support for Valgrind memcheck
-$(OPT)$(*) compiled with support for Valgrind drd
-$(OPT)$(*) compiled with support for shutdown state
-$(OPT)$(*) compiled with libndctl 63+
-$(*)
-$(*)Log level NONE
-$(*)Log level ERROR
-$(*)Log level WARNING
-$(*)Log level INFO
-$(*)Log level DEBUG
-$(*)
+$(nW) <1> $(nW) $(nW) pid $(N): program: $(nW)
+$(nW) <1> $(nW) $(nW) ut version 1.0
+$(nW) <1> $(nW) $(nW) src version: $(nW)
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind pmemcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind helgrind
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind memcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind drd
+$(nW) <1> $(nW) $(nW) compiled with support for shutdown state
+$(nW) <1> $(nW) $(nW) compiled with libndctl 63+
+$(nW) <3> $(nW) $(nW) 
+$(nW) <1> $(nW) $(nW) Log level ALWAYS
+$(nW) <1> $(nW) $(nW) Log level ERROR
+$(nW) <2> $(nW) $(nW) Log level WARNING
+$(nW) <3> $(nW) $(nW) Log level INFO
+$(nW) <4> $(nW) $(nW) Log level DEBUG
+$(nW) <3> $(nW) $(nW) 
diff --git a/src/test/traces/redir_stderr1.log.match b/src/test/traces/redir_stderr1.log.match
index 3d739c871d8..e69de29bb2d 100644
--- a/src/test/traces/redir_stderr1.log.match
+++ b/src/test/traces/redir_stderr1.log.match
@@ -1 +0,0 @@
-$(*)Log level NONE
diff --git a/src/test/traces/redir_stderr2.log.match b/src/test/traces/redir_stderr2.log.match
index 0ff6e699564..79271cadab2 100644
--- a/src/test/traces/redir_stderr2.log.match
+++ b/src/test/traces/redir_stderr2.log.match
@@ -1,11 +1,11 @@
-$(*)
-$(*)
-$(*)
-$(OPT)$(*) compiled with support for Valgrind pmemcheck
-$(OPT)$(*) compiled with support for Valgrind helgrind
-$(OPT)$(*) compiled with support for Valgrind memcheck
-$(OPT)$(*) compiled with support for Valgrind drd
-$(OPT)$(*) compiled with support for shutdown state
-$(OPT)$(*) compiled with libndctl 63+
-$(*)Log level NONE
-$(*)Log level ERROR
+$(nW) <1> $(nW) $(nW) pid $(N): program: $(nW)
+$(nW) <1> $(nW) $(nW) ut version 1.0
+$(nW) <1> $(nW) $(nW) src version: $(nW)
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind pmemcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind helgrind
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind memcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind drd
+$(nW) <1> $(nW) $(nW) compiled with support for shutdown state
+$(nW) <1> $(nW) $(nW) compiled with libndctl 63+
+$(nW) <1> $(nW) $(nW) Log level ALWAYS
+$(nW) <1> $(nW) $(nW) Log level ERROR
diff --git a/src/test/traces/redir_stderr3.log.match b/src/test/traces/redir_stderr3.log.match
index 1f4b14419a3..dfee35a04d7 100644
--- a/src/test/traces/redir_stderr3.log.match
+++ b/src/test/traces/redir_stderr3.log.match
@@ -1,12 +1,12 @@
-$(*)
-$(*)
-$(*)
-$(OPT)$(*) compiled with support for Valgrind pmemcheck
-$(OPT)$(*) compiled with support for Valgrind helgrind
-$(OPT)$(*) compiled with support for Valgrind memcheck
-$(OPT)$(*) compiled with support for Valgrind drd
-$(OPT)$(*) compiled with support for shutdown state
-$(OPT)$(*) compiled with libndctl 63+
-$(*)Log level NONE
-$(*)Log level ERROR
-$(*)Log level WARNING
+$(nW) <1> $(nW) $(nW) pid $(N): program: $(nW)
+$(nW) <1> $(nW) $(nW) ut version 1.0
+$(nW) <1> $(nW) $(nW) src version: $(nW)
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind pmemcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind helgrind
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind memcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind drd
+$(nW) <1> $(nW) $(nW) compiled with support for shutdown state
+$(nW) <1> $(nW) $(nW) compiled with libndctl 63+
+$(nW) <1> $(nW) $(nW) Log level ALWAYS
+$(nW) <1> $(nW) $(nW) Log level ERROR
+$(nW) <2> $(nW) $(nW) Log level WARNING
diff --git a/src/test/traces/redir_stderr4.log.match b/src/test/traces/redir_stderr4.log.match
index 97f9f09bf48..15cb460f06a 100644
--- a/src/test/traces/redir_stderr4.log.match
+++ b/src/test/traces/redir_stderr4.log.match
@@ -1,15 +1,15 @@
-$(*)
-$(*)
-$(*)
-$(OPT)$(*) compiled with support for Valgrind pmemcheck
-$(OPT)$(*) compiled with support for Valgrind helgrind
-$(OPT)$(*) compiled with support for Valgrind memcheck
-$(OPT)$(*) compiled with support for Valgrind drd
-$(OPT)$(*) compiled with support for shutdown state
-$(OPT)$(*) compiled with libndctl 63+
-$(*)
-$(*)Log level NONE
-$(*)Log level ERROR
-$(*)Log level WARNING
-$(*)Log level INFO
-$(*)
+$(nW) <1> $(nW) $(nW) pid $(N): program: $(nW)
+$(nW) <1> $(nW) $(nW) ut version 1.0
+$(nW) <1> $(nW) $(nW) src version: $(nW)
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind pmemcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind helgrind
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind memcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind drd
+$(nW) <1> $(nW) $(nW) compiled with support for shutdown state
+$(nW) <1> $(nW) $(nW) compiled with libndctl 63+
+$(nW) <3> $(nW) $(nW) 
+$(nW) <1> $(nW) $(nW) Log level ALWAYS
+$(nW) <1> $(nW) $(nW) Log level ERROR
+$(nW) <2> $(nW) $(nW) Log level WARNING
+$(nW) <3> $(nW) $(nW) Log level INFO
+$(nW) <3> $(nW) $(nW) 
diff --git a/src/test/traces/redir_stderr5.log.match b/src/test/traces/redir_stderr5.log.match
index 9209b0590f2..a3733783de9 100644
--- a/src/test/traces/redir_stderr5.log.match
+++ b/src/test/traces/redir_stderr5.log.match
@@ -1,16 +1,16 @@
-$(*)
-$(*)
-$(*)
-$(OPT)$(*) compiled with support for Valgrind pmemcheck
-$(OPT)$(*) compiled with support for Valgrind helgrind
-$(OPT)$(*) compiled with support for Valgrind memcheck
-$(OPT)$(*) compiled with support for Valgrind drd
-$(OPT)$(*) compiled with support for shutdown state
-$(OPT)$(*) compiled with libndctl 63+
-$(*)
-$(*)Log level NONE
-$(*)Log level ERROR
-$(*)Log level WARNING
-$(*)Log level INFO
-$(*)Log level DEBUG
-$(*)
+$(nW) <1> $(nW) $(nW) pid $(N): program: $(nW)
+$(nW) <1> $(nW) $(nW) ut version 1.0
+$(nW) <1> $(nW) $(nW) src version: $(nW)
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind pmemcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind helgrind
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind memcheck
+$(nW) <1> $(nW) $(nW) compiled with support for Valgrind drd
+$(nW) <1> $(nW) $(nW) compiled with support for shutdown state
+$(nW) <1> $(nW) $(nW) compiled with libndctl 63+
+$(nW) <3> $(nW) $(nW) 
+$(nW) <1> $(nW) $(nW) Log level ALWAYS
+$(nW) <1> $(nW) $(nW) Log level ERROR
+$(nW) <2> $(nW) $(nW) Log level WARNING
+$(nW) <3> $(nW) $(nW) Log level INFO
+$(nW) <4> $(nW) $(nW) Log level DEBUG
+$(nW) <3> $(nW) $(nW) 
diff --git a/src/test/traces/redir_stderr6.log.match b/src/test/traces/redir_stderr6.log.match
deleted file mode 100644
index c96567c6243..00000000000
--- a/src/test/traces/redir_stderr6.log.match
+++ /dev/null
@@ -1,16 +0,0 @@
-$(*)
-$(*)
-$(*)
-$(OPT)$(*) compiled with support for Valgrind pmemcheck
-$(OPT)$(*) compiled with support for Valgrind helgrind
-$(OPT)$(*) compiled with support for Valgrind memcheck
-$(OPT)$(*) compiled with support for Valgrind drd
-$(OPT)$(*) compiled with support for shutdown state
-$(OPT)$(*) compiled with libndctl 63+
-$(*)
-<ut>: <0> [traces.c:$(*) main]$(W)Log level NONE
-<ut>: <1> [traces.c:$(*) main]$(W)Log level ERROR
-<ut>: <2> [traces.c:$(*) main]$(W)Log level WARNING
-<ut>: <3> [traces.c:$(*) main]$(W)Log level INFO
-<ut>: <4> [traces.c:$(*) main]$(W)Log level DEBUG
-$(*)
diff --git a/src/test/traces/traces.c b/src/test/traces/traces.c
index e61046bcebf..05e08499026 100644
--- a/src/test/traces/traces.c
+++ b/src/test/traces/traces.c
@@ -24,7 +24,7 @@ main(int argc, char *argv[])
 	/* Execute test */
 	common_init(LOG_PREFIX, LOG_LEVEL_VAR, LOG_FILE_VAR,
 			MAJOR_VERSION, MINOR_VERSION);
-	LOG(0, "Log level NONE");
+	CORE_LOG_ALWAYS("Log level ALWAYS");
 	CORE_LOG_ERROR("Log level ERROR");
 	CORE_LOG_WARNING("Log level WARNING");
 	LOG(3, "Log level INFO");