diff --git a/dbms/src/IO/tests/read_buffer_aio.cpp b/dbms/src/IO/tests/read_buffer_aio.cpp
index 18b4d4ac879..aca8c26cda5 100644
--- a/dbms/src/IO/tests/read_buffer_aio.cpp
+++ b/dbms/src/IO/tests/read_buffer_aio.cpp
@@ -14,12 +14,13 @@ namespace
 {
 
 void run();
-void prepare(size_t s, std::string & directory, std::string  & filename, std::string & buf);
-void prepare2(std::string & directory, std::string  & filename, std::string & buf);
-void prepare3(std::string & directory, std::string  & filename, std::string & buf);
-void prepare4(std::string & directory, std::string  & filename, std::string & buf);
+void prepare(size_t s, std::string  & filename, std::string & buf);
+void prepare2(std::string  & filename, std::string & buf);
+void prepare3(std::string  & filename, std::string & buf);
+void prepare4(std::string  & filename, std::string & buf);
+std::string createTmpFile();
 void die(const std::string & msg);
-void run_test(unsigned int num, const std::function<bool()> func);
+void runTest(unsigned int num, const std::function<bool()> func);
 
 bool test1(const std::string & filename);
 bool test2(const std::string & filename, const std::string & buf);
@@ -46,30 +47,25 @@ void run()
 {
 	namespace fs = boost::filesystem;
 
-	std::string directory;
 	std::string filename;
 	std::string buf;
-	prepare(10 * DEFAULT_AIO_FILE_BLOCK_SIZE, directory, filename, buf);
+	prepare(10 * DEFAULT_AIO_FILE_BLOCK_SIZE, filename, buf);
 
-	std::string directory2;
 	std::string filename2;
 	std::string buf2;
-	prepare(2 * DEFAULT_AIO_FILE_BLOCK_SIZE - 3, directory2, filename2, buf2);
+	prepare(2 * DEFAULT_AIO_FILE_BLOCK_SIZE - 3, filename2, buf2);
 
-	std::string directory3;
 	std::string filename3;
 	std::string buf3;
-	prepare2(directory3, filename3, buf3);
+	prepare2(filename3, buf3);
 
-	std::string directory4;
 	std::string filename4;
 	std::string buf4;
-	prepare3(directory4, filename4, buf4);
+	prepare3(filename4, buf4);
 
-	std::string directory5;
 	std::string filename5;
 	std::string buf5;
-	prepare4(directory5, filename5, buf5);
+	prepare4(filename5, buf5);
 
 	const std::vector<std::function<bool()> > tests =
 	{
@@ -99,27 +95,21 @@ void run()
 	for (const auto & test : tests)
 	{
 		++num;
-		run_test(num, test);
+		runTest(num, test);
 	}
 
-	fs::remove_all(directory);
-	fs::remove_all(directory2);
-	fs::remove_all(directory3);
-	fs::remove_all(directory4);
-	fs::remove_all(directory5);
+	fs::remove_all(fs::path(filename).parent_path().string());
+	fs::remove_all(fs::path(filename2).parent_path().string());
+	fs::remove_all(fs::path(filename3).parent_path().string());
+	fs::remove_all(fs::path(filename4).parent_path().string());
+	fs::remove_all(fs::path(filename5).parent_path().string());
 }
 
-void prepare(size_t s, std::string & directory, std::string  & filename, std::string & buf)
+void prepare(size_t s, std::string  & filename, std::string & buf)
 {
 	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	directory = std::string(dir);
-	filename = directory + "/foo";
+	filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 	buf.reserve(n);
@@ -134,15 +124,9 @@ void prepare(size_t s, std::string & directory, std::string  & filename, std::st
 	out << buf;
 }
 
-void prepare2(std::string & directory, std::string & filename, std::string & buf)
+void prepare2(std::string & filename, std::string & buf)
 {
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	directory = std::string(dir);
-	filename = directory + "/foo";
+	filename = createTmpFile();
 
 	buf = "122333444455555666666777777788888888999999999";
 
@@ -153,15 +137,9 @@ void prepare2(std::string & directory, std::string & filename, std::string & buf
 	out << buf;
 }
 
-void prepare3(std::string & directory, std::string & filename, std::string & buf)
+void prepare3(std::string & filename, std::string & buf)
 {
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	directory = std::string(dir);
-	filename = directory + "/foo";
+	filename = createTmpFile();
 
 	buf = "122333444455555666666777777788888888999999999";
 
@@ -173,17 +151,11 @@ void prepare3(std::string & directory, std::string & filename, std::string & buf
 	out << buf;
 }
 
-void prepare4(std::string & directory, std::string & filename, std::string & buf)
+void prepare4(std::string & filename, std::string & buf)
 {
 	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	directory = std::string(dir);
-	filename = directory + "/foo";
+	filename = createTmpFile();
 
 	std::ofstream out(filename.c_str());
 	if (!out.is_open())
@@ -196,13 +168,23 @@ void prepare4(std::string & directory, std::string & filename, std::string & buf
 	out << buf;
 }
 
+std::string createTmpFile()
+{
+	char pattern[] = "/tmp/fileXXXXXX";
+	char * dir = ::mkdtemp(pattern);
+	if (dir == nullptr)
+		die("Could not create directory");
+
+	return std::string(dir) + "/foo";
+}
+
 void die(const std::string & msg)
 {
 	std::cout << msg << "\n";
 	::exit(EXIT_FAILURE);
 }
 
-void run_test(unsigned int num, const std::function<bool()> func)
+void runTest(unsigned int num, const std::function<bool()> func)
 {
 	bool ok;
 
diff --git a/dbms/src/IO/tests/write_buffer_aio.cpp b/dbms/src/IO/tests/write_buffer_aio.cpp
index 53ff48d4aec..8dd34dc6864 100644
--- a/dbms/src/IO/tests/write_buffer_aio.cpp
+++ b/dbms/src/IO/tests/write_buffer_aio.cpp
@@ -11,9 +11,13 @@
 namespace
 {
 
+namespace fs = boost::filesystem;
+
 void run();
 void die(const std::string & msg);
-void run_test(unsigned int num, const std::function<bool()> func);
+void runTest(unsigned int num, const std::function<bool()> func);
+std::string createTmpFile();
+std::string generateString(size_t n);
 
 bool test1();
 bool test2();
@@ -46,7 +50,7 @@ void run()
 	for (const auto & test : tests)
 	{
 		++num;
-		run_test(num, test);
+		runTest(num, test);
 	}
 }
 
@@ -56,7 +60,7 @@ void die(const std::string & msg)
 	::exit(EXIT_FAILURE);
 }
 
-void run_test(unsigned int num, const std::function<bool()> func)
+void runTest(unsigned int num, const std::function<bool()> func)
 {
 	bool ok;
 
@@ -81,21 +85,19 @@ void run_test(unsigned int num, const std::function<bool()> func)
 		std::cout << "Test " << num << " failed\n";
 }
 
-bool test1()
+std::string createTmpFile()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
 	char pattern[] = "/tmp/fileXXXXXX";
 	char * dir = ::mkdtemp(pattern);
 	if (dir == nullptr)
 		die("Could not create directory");
 
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	return std::string(dir) + "/foo";
+}
 
-	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
+std::string generateString(size_t n)
+{
+	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
 	std::string buf;
 	buf.reserve(n);
@@ -103,6 +105,17 @@ bool test1()
 	for (size_t i = 0; i < n; ++i)
 		buf += symbols[i % symbols.length()];
 
+	return buf;
+}
+
+bool test1()
+{
+	std::string filename = createTmpFile();
+
+	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
+
+	std::string buf = generateString(n);
+
 	{
 		DB::WriteBufferAIO out(filename, 3 * DEFAULT_AIO_FILE_BLOCK_SIZE);
 
@@ -121,32 +134,18 @@ bool test1()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	return (received == buf);
 }
 
 bool test2()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	{
 		DB::WriteBufferAIO out(filename, 3 * DEFAULT_AIO_FILE_BLOCK_SIZE);
@@ -168,7 +167,7 @@ bool test2()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	if (received.substr(0, buf.length() / 2) != buf.substr(0, buf.length() / 2))
 		return false;
@@ -182,25 +181,11 @@ bool test2()
 
 bool test3()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	{
 		DB::WriteBufferAIO out(filename, 3 * DEFAULT_AIO_FILE_BLOCK_SIZE);
@@ -229,32 +214,18 @@ bool test3()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	return (received == buf.substr(0, buf.length() / 2));
 }
 
 bool test4()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	{
 		DB::WriteBufferAIO out(filename, 3 * DEFAULT_AIO_FILE_BLOCK_SIZE);
@@ -283,7 +254,7 @@ bool test4()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	if (received.substr(0, buf.length()) != buf)
 		return false;
@@ -296,25 +267,11 @@ bool test4()
 
 bool test5()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	{
 		DB::WriteBufferAIO out(filename, 3 * DEFAULT_AIO_FILE_BLOCK_SIZE);
@@ -335,32 +292,18 @@ bool test5()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	return received.substr(1) == buf;
 }
 
 bool test6()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	std::string buf2 = "1111111111";
 
@@ -385,7 +328,7 @@ bool test6()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	if (received.substr(3, 8 * DEFAULT_AIO_FILE_BLOCK_SIZE) != buf.substr(0, 8 * DEFAULT_AIO_FILE_BLOCK_SIZE))
 		return false;
@@ -401,17 +344,7 @@ bool test6()
 
 bool test7()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	std::string buf2 = "11111111112222222222";
 
@@ -441,24 +374,14 @@ bool test7()
 		return false;
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	return true;
 }
 
 bool test8()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	std::string buf2 = "11111111112222222222";
 
@@ -488,32 +411,18 @@ bool test8()
 		return false;
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	return true;
 }
 
 bool test9()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 3 * DEFAULT_AIO_FILE_BLOCK_SIZE;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	std::string buf2(DEFAULT_AIO_FILE_BLOCK_SIZE + 10, '1');
 
@@ -538,7 +447,7 @@ bool test9()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	if (received.substr(3, 2 * DEFAULT_AIO_FILE_BLOCK_SIZE) != buf.substr(0, 2 * DEFAULT_AIO_FILE_BLOCK_SIZE))
 		return false;
@@ -551,25 +460,11 @@ bool test9()
 
 bool test10()
 {
-	namespace fs = boost::filesystem;
-
-	static const std::string symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
-
-	char pattern[] = "/tmp/fileXXXXXX";
-	char * dir = ::mkdtemp(pattern);
-	if (dir == nullptr)
-		die("Could not create directory");
-
-	const std::string directory = std::string(dir);
-	const std::string filename = directory + "/foo";
+	std::string filename = createTmpFile();
 
 	size_t n = 10 * DEFAULT_AIO_FILE_BLOCK_SIZE + 3;
 
-	std::string buf;
-	buf.reserve(n);
-
-	for (size_t i = 0; i < n; ++i)
-		buf += symbols[i % symbols.length()];
+	std::string buf = generateString(n);
 
 	{
 		DB::WriteBufferAIO out(filename, 3 * DEFAULT_AIO_FILE_BLOCK_SIZE);
@@ -589,7 +484,7 @@ bool test10()
 	std::string received{ std::istreambuf_iterator<char>(in), std::istreambuf_iterator<char>() };
 
 	in.close();
-	fs::remove_all(directory);
+	fs::remove_all(fs::path(filename).parent_path().string());
 
 	return (received == buf);
 }