diff --git a/tests/integration/CMakeLists.txt b/tests/integration/CMakeLists.txt
index b3a084766ed05440474c7f33c55816a03136ad90..f29f079e9bbb7081e3e16505ec179e41b3b3e924 100644
--- a/tests/integration/CMakeLists.txt
+++ b/tests/integration/CMakeLists.txt
@@ -46,6 +46,15 @@ gkfs_add_python_test(
     SOURCE shell/
 )
 
+
+gkfs_add_python_test(
+    NAME test_data
+    PYTHON_VERSION 3.6
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/tests/integration
+    SOURCE data/
+)
+
+
 if(GKFS_INSTALL_TESTS)
     install(DIRECTORY harness
         DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/gkfs/tests/integration
@@ -89,6 +98,14 @@ if(GKFS_INSTALL_TESTS)
     )
 
 
+    install(DIRECTORY data
+    DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/gkfs/tests/integration
+    FILES_MATCHING
+        REGEX ".*\\.py"
+        PATTERN "__pycache__" EXCLUDE
+        PATTERN ".pytest_cache" EXCLUDE
+    )
+
     install(DIRECTORY shell
         DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/gkfs/tests/integration
         FILES_MATCHING
diff --git a/tests/integration/data/README.md b/tests/integration/data/README.md
new file mode 100644
index 0000000000000000000000000000000000000000..8bde8d433aea166a34b828be9663c81f899d8b8b
--- /dev/null
+++ b/tests/integration/data/README.md
@@ -0,0 +1,4 @@
+# README
+
+This directory contains functional tests for any data-related
+functionalities in GekkoFS.
diff --git a/tests/integration/data/test_data_integrity.py b/tests/integration/data/test_data_integrity.py
new file mode 100644
index 0000000000000000000000000000000000000000..67b88611c75bd414e64d99e4028a5e1b78204e76
--- /dev/null
+++ b/tests/integration/data/test_data_integrity.py
@@ -0,0 +1,105 @@
+################################################################################
+#  Copyright 2018-2020, Barcelona Supercomputing Center (BSC), Spain           #
+#  Copyright 2015-2020, Johannes Gutenberg Universitaet Mainz, Germany         #
+#                                                                              #
+#  This software was partially supported by the                                #
+#  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).   #
+#                                                                              #
+#  This software was partially supported by the                                #
+#  ADA-FS project under the SPPEXA project funded by the DFG.                  #
+#                                                                              #
+#  SPDX-License-Identifier: MIT                                                #
+################################################################################
+
+import harness
+from pathlib import Path
+import errno
+import stat
+import os
+import ctypes
+import sh
+import sys
+import pytest
+import string
+import random
+from harness.logger import logger
+
+nonexisting = "nonexisting"
+chunksize_start = 128192
+chunksize_end = 2097153
+step = 4096*9
+
+def generate_random_data(size):
+    return ''.join([random.choice(string.ascii_letters + string.digits) for _ in range(size)])
+
+
+
+
+#@pytest.mark.xfail(reason="invalid errno returned on success")
+def test_data_integrity(gkfs_daemon, gkfs_client):
+    """Test several data write-read commands and check that the data is correct"""
+    topdir = gkfs_daemon.mountdir / "top"
+    file_a = topdir / "file_a"
+
+    # create topdir
+    ret = gkfs_client.mkdir(
+            topdir,
+            stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
+
+    assert ret.retval == 0
+    assert ret.errno == 115 #FIXME: Should be 0!
+
+    # test statx on existing dir
+    ret = gkfs_client.statx(0, topdir, 0, 0)
+
+    assert ret.retval == 0
+    assert ret.errno == 115 #FIXME: Should be 0!
+    assert stat.S_ISDIR(ret.statbuf.stx_mode)
+
+    ret = gkfs_client.open(file_a,
+                   os.O_CREAT,
+                   stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)
+
+    assert ret.retval != -1
+
+
+    # test statx on existing file
+    ret = gkfs_client.statx(0, file_a, 0, 0)
+
+    assert ret.retval == 0
+    assert (stat.S_ISDIR(ret.statbuf.stx_mode)==0)
+    assert (ret.statbuf.stx_size == 0)
+
+
+    # Step 1 - small sizes
+    
+    # Generate writes
+    # Read data
+    # Compare buffer
+
+    
+    for i in range (1, 512, 64):
+        buf = bytes(generate_random_data(i), sys.stdout.encoding)
+        
+        ret = gkfs_client.write(file_a, buf, i)
+
+        assert ret.retval == i
+        ret = gkfs_client.statx(0, file_a, 0, 0)
+
+        assert ret.retval == 0
+        assert (ret.statbuf.stx_size == i)
+
+        ret = gkfs_client.read(file_a, i)
+        assert ret.retval== i
+        assert ret.buf == buf
+
+
+    # Step 2 - Compare bigger sizes exceeding typical chunksize
+    for i in range (chunksize_start, chunksize_end, step):
+        ret = gkfs_client.write_validate(file_a, i)
+        assert ret.retval == 1
+
+
+    return
+
+
diff --git a/tests/integration/harness/CMakeLists.txt b/tests/integration/harness/CMakeLists.txt
index 7a8090e79cce731df891167a6ee2535cd8c03725..13e6d5d956deaaf81a02def3238661de19dddef4 100644
--- a/tests/integration/harness/CMakeLists.txt
+++ b/tests/integration/harness/CMakeLists.txt
@@ -26,6 +26,7 @@ add_executable(gkfs.io
     gkfs.io/pwritev.cpp
     gkfs.io/statx.cpp
     gkfs.io/lseek.cpp
+    gkfs.io/write_validate.cpp
 )
 
 include(FetchContent)
diff --git a/tests/integration/harness/gkfs.io/commands.hpp b/tests/integration/harness/gkfs.io/commands.hpp
index 7d111c60943651794822a1ce321394bbe0c85e54..0fc3041d852aee4254e3ea2b2134a888c138a6a0 100644
--- a/tests/integration/harness/gkfs.io/commands.hpp
+++ b/tests/integration/harness/gkfs.io/commands.hpp
@@ -67,4 +67,7 @@ statx_init(CLI::App& app);
 void
 lseek_init(CLI::App& app);
 
+void
+write_validate_init(CLI::App& app);
+
 #endif // IO_COMMANDS_HPP
diff --git a/tests/integration/harness/gkfs.io/main.cpp b/tests/integration/harness/gkfs.io/main.cpp
index e946d1b116e9185f3eeed82c3ea7e25d7a5caebe..426df6a7e12e7dd801c42c8015ff9ad0af6b5406 100644
--- a/tests/integration/harness/gkfs.io/main.cpp
+++ b/tests/integration/harness/gkfs.io/main.cpp
@@ -38,6 +38,7 @@ init_commands(CLI::App& app) {
     statx_init(app);
     #endif
     lseek_init(app);
+    write_validate_init(app);
 }
 
 
diff --git a/tests/integration/harness/gkfs.io/write_validate.cpp b/tests/integration/harness/gkfs.io/write_validate.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..54e9d10bab49ff14515bd8921e605da4f51e722f
--- /dev/null
+++ b/tests/integration/harness/gkfs.io/write_validate.cpp
@@ -0,0 +1,169 @@
+/*
+  Copyright 2018-2020, Barcelona Supercomputing Center (BSC), Spain
+  Copyright 2015-2020, Johannes Gutenberg Universitaet Mainz, Germany
+
+  This software was partially supported by the
+  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).
+
+  This software was partially supported by the
+  ADA-FS project under the SPPEXA project funded by the DFG.
+
+  SPDX-License-Identifier: MIT
+*/
+
+/* C++ includes */
+#include <CLI/CLI.hpp>
+#include <nlohmann/json.hpp>
+#include <memory>
+#include <fmt/format.h>
+#include <commands.hpp>
+#include <reflection.hpp>
+#include <serialize.hpp>
+#include <binary_buffer.hpp>
+
+/* C includes */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+using json = nlohmann::json;
+
+struct write_validate_options {
+    bool verbose;
+    std::string pathname;
+    ::size_t count;
+
+    REFL_DECL_STRUCT(write_validate_options,
+        REFL_DECL_MEMBER(bool, verbose),
+        REFL_DECL_MEMBER(std::string, pathname),
+        REFL_DECL_MEMBER(::size_t, count)
+    );
+};
+
+struct write_validate_output {
+    int retval;
+    int errnum;
+
+    REFL_DECL_STRUCT(write_validate_output,
+        REFL_DECL_MEMBER(int, retval),
+        REFL_DECL_MEMBER(int, errnum)
+    );
+};
+
+void
+to_json(json& record, 
+        const write_validate_output& out) {
+    record = serialize(out);
+}
+
+void 
+write_validate_exec(const write_validate_options& opts) {
+
+    int fd = ::open(opts.pathname.c_str(), O_WRONLY);
+
+    if(fd == -1) {
+        if(opts.verbose) {
+            fmt::print("write_validate(pathname=\"{}\", count={}) = {}, errno: {} [{}]\n", 
+                    opts.pathname, opts.count, fd, errno, ::strerror(errno));
+            return;
+        }
+
+        json out = write_validate_output{fd, errno};
+        fmt::print("{}\n", out.dump(2));
+
+        return;
+    }
+
+
+    std::string data = "";
+    for (::size_t i = 0 ; i < opts.count; i++)
+    {
+        data += char((i%10)+'0');
+    }
+
+    io::buffer buf(data);
+
+    auto rv = ::write(fd, buf.data(), opts.count);
+
+    if(opts.verbose) {
+        fmt::print("write_validate(pathname=\"{}\", count={}) = {}, errno: {} [{}]\n", 
+                   opts.pathname, opts.count, rv, errno, ::strerror(errno));
+        return;
+    }
+
+    if (rv < 0 or ::size_t(rv) != opts.count) {
+        json out = write_validate_output{(int)rv, errno};
+        fmt::print("{}\n", out.dump(2));
+        return;
+    }
+
+
+    io::buffer bufread(opts.count);
+
+    size_t total = 0;
+    do{
+        rv = ::read(fd, bufread.data(), opts.count-total);
+        total += rv;
+    } while (rv > 0 and total < opts.count);
+
+    if (rv < 0 and total != opts.count) {
+        json out = write_validate_output{(int)rv, errno};
+        fmt::print("{}\n", out.dump(2));
+        return;
+    }
+
+    if ( memcmp(buf.data(),bufread.data(),opts.count) ) {
+        rv = 1;
+        errno = 0;
+        json out = write_validate_output{(int)rv, errno};
+        fmt::print("{}\n", out.dump(2));
+        return;
+    }
+    else  {
+        rv = 2;
+        errno = EINVAL;
+        json out = write_validate_output{(int)-1, errno};
+        fmt::print("{}\n", out.dump(2));
+    }
+
+}
+
+void
+write_validate_init(CLI::App& app) {
+
+    // Create the option and subcommand objects
+    auto opts = std::make_shared<write_validate_options>();
+    auto* cmd = app.add_subcommand(
+            "write_validate", 
+            "Execute the write()-read() system call and compare the content of the buffer");
+
+    // Add options to cmd, binding them to opts
+    cmd->add_flag(
+            "-v,--verbose",
+            opts->verbose,
+            "Produce human writeable output"
+        );
+
+    cmd->add_option(
+            "pathname", 
+            opts->pathname,
+            "Directory name"
+        )
+        ->required()
+        ->type_name("");
+
+    cmd->add_option(
+            "count", 
+            opts->count,
+            "Number of bytes to test"
+        )
+        ->required()
+        ->type_name("");
+
+    cmd->callback([opts]() { 
+        write_validate_exec(*opts); 
+    });
+}
+
+
diff --git a/tests/integration/harness/io.py b/tests/integration/harness/io.py
index f50d3d9f45ec44a3b8f40923154e773e35410ded..d5acf60bf5a79314b05551113cc3bf2a12e1f1ca 100644
--- a/tests/integration/harness/io.py
+++ b/tests/integration/harness/io.py
@@ -293,6 +293,17 @@ class LseekOutputSchema(Schema):
     def make_object(self, data, **kwargs):
         return namedtuple('LseekReturn', ['retval', 'errno'])(**data)
 
+
+class WriteValidateOutputSchema(Schema):
+    """Schema to deserialize the results of a write() execution"""
+
+    retval = fields.Integer(required=True)
+    errno = Errno(data_key='errnum', required=True)
+
+    @post_load
+    def make_object(self, data, **kwargs):
+        return namedtuple('WriteValidateReturn', ['retval', 'errno'])(**data)
+
 class IOParser:
 
     OutputSchemas = {
@@ -312,6 +323,7 @@ class IOParser:
         'stat'    : StatOutputSchema(),
         'statx'   : StatxOutputSchema(),
         'lseek'   : LseekOutputSchema(),
+        'write_validate' : WriteValidateOutputSchema(),
     }
 
     def parse(self, command, output):