diff --git a/Makefile b/Makefile
index 093736a6..731c1224 100644
--- a/Makefile
+++ b/Makefile
@@ -1,13 +1,15 @@
 BLOCKSTORE_OBJS := allocator.o blockstore.o blockstore_init.o blockstore_open.o blockstore_journal.o blockstore_read.o \
 	blockstore_write.o blockstore_sync.o blockstore_stable.o blockstore_flush.o crc32c.o ringloop.o timerfd_interval.o osd.o
 CXXFLAGS := -g -O3 -Wall -Wno-sign-compare -Wno-comment -Wno-parentheses -Wno-pointer-arith -fPIC -fdiagnostics-color=always
-all: $(BLOCKSTORE_OBJS) test test_blockstore libfio_blockstore.so
+all: $(BLOCKSTORE_OBJS) test test_blockstore libfio_blockstore.so osd
 clean:
 	rm -f *.o
 crc32c.o: crc32c.c
 	g++ $(CXXFLAGS) -c -o $@ $<
 %.o: %.cpp allocator.h blockstore_flush.h blockstore.h blockstore_init.h blockstore_journal.h crc32c.h ringloop.h xor.h timerfd_interval.h
 	g++ $(CXXFLAGS) -c -o $@ $<
+osd: $(BLOCKSTORE_OBJS) osd_main.cpp osd.h osd_ops.h
+	g++ $(CXXFLAGS) -ltcmalloc_minimal -luring -o osd osd_main.cpp $(BLOCKSTORE_OBJS)
 test: test.cpp
 	g++ $(CXXFLAGS) -o test -luring test.cpp
 test_blockstore: $(BLOCKSTORE_OBJS) test_blockstore.cpp
diff --git a/osd.cpp b/osd.cpp
index 8dd717b4..8125304a 100644
--- a/osd.cpp
+++ b/osd.cpp
@@ -4,10 +4,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
-#include <unordered_map>
-
-#include "osd_ops.h"
-#include "ringloop.h"
+#include "osd.h"
 
 #define CL_READ_OP 1
 #define CL_READ_DATA 2
@@ -16,97 +13,15 @@
 #define CL_WRITE_REPLY 2
 #define CL_WRITE_DATA 3
 
-struct osd_op_t
+osd_t::osd_t(blockstore_config_t & config, blockstore *bs, ring_loop_t *ringloop)
 {
-    int peer_fd;
-    union
-    {
-        osd_any_op_t op;
-        uint8_t op_buf[OSD_OP_PACKET_SIZE] = { 0 };
-    };
-    union
-    {
-        osd_any_reply_t reply;
-        uint8_t reply_buf[OSD_REPLY_PACKET_SIZE] = { 0 };
-    };
-    blockstore_operation bs_op;
-    void *buf = NULL;
+    bind_address = config["bind_address"];
+    if (bind_address == "")
+        bind_address = "0.0.0.0";
+    bind_port = strtoull(config["bind_port"].c_str(), NULL, 10);
+    if (!bind_port || bind_port > 65535)
+        bind_port = 11203;
 
-    ~osd_op_t()
-    {
-        if (buf)
-            free(buf);
-    }
-};
-
-struct osd_client_t
-{
-    sockaddr_in peer_addr;
-    socklen_t peer_addr_size;
-    int peer_fd;
-    //int in_flight_ops = 0;
-
-    // Read state
-    bool read_ready = false;
-    bool reading = false;
-    osd_op_t *read_op = NULL;
-    iovec read_iov;
-    msghdr read_msg;
-    void *read_buf = NULL;
-    int read_remaining = 0;
-    int read_state = 0;
-
-    // Completed operations to send replies back to the client
-    std::deque<osd_op_t*> completions;
-
-    // Write state
-    osd_op_t *write_op = NULL;
-    iovec write_iov;
-    msghdr write_msg;
-    void *write_buf = NULL;
-    int write_remaining = 0;
-    int write_state = 0;
-};
-
-class osd_t
-{
-    // config
-
-    int client_queue_depth = 128;
-
-    // fields
-
-    blockstore *bs;
-    ring_loop_t *ringloop;
-
-    int wait_state = 0;
-    int epoll_fd = 0;
-    int listen_fd = 0;
-    ring_consumer_t consumer;
-
-    std::string bind_address;
-    int bind_port, listen_backlog;
-
-    std::unordered_map<int,osd_client_t> clients;
-    std::vector<int> read_ready_clients;
-    std::vector<int> write_ready_clients;
-
-    void loop();
-    int handle_epoll_events();
-    void stop_client(int peer_fd);
-    void read_requests();
-    void handle_read(ring_data_t *data, int peer_fd);
-    void enqueue_op(osd_op_t *cur_op);
-    void send_replies();
-    void make_reply(osd_op_t *op);
-    void handle_send(ring_data_t *data, int peer_fd);
-public:
-    osd_t(blockstore *bs, ring_loop_t *ringloop);
-    ~osd_t();
-};
-
-osd_t::osd_t(blockstore *bs, ring_loop_t *ringloop)
-{
     this->bs = bs;
     this->ringloop = ringloop;
 
diff --git a/osd.h b/osd.h
new file mode 100644
index 00000000..5e38f34a
--- /dev/null
+++ b/osd.h
@@ -0,0 +1,97 @@
+#pragma once
+
+#include <arpa/inet.h>
+
+#include <unordered_map>
+
+#include "ringloop.h"
+#include "osd_ops.h"
+
+struct osd_op_t
+{
+    int peer_fd;
+    union
+    {
+        osd_any_op_t op;
+        uint8_t op_buf[OSD_OP_PACKET_SIZE] = { 0 };
+    };
+    union
+    {
+        osd_any_reply_t reply;
+        uint8_t reply_buf[OSD_REPLY_PACKET_SIZE] = { 0 };
+    };
+    blockstore_operation bs_op;
+    void *buf = NULL;
+
+    ~osd_op_t()
+    {
+        if (buf)
+            free(buf);
+    }
+};
+
+struct osd_client_t
+{
+    sockaddr_in peer_addr;
+    socklen_t peer_addr_size;
+    int peer_fd;
+    //int in_flight_ops = 0;
+
+    // Read state
+    bool read_ready = false;
+    bool reading = false;
+    osd_op_t *read_op = NULL;
+    iovec read_iov;
+    msghdr read_msg;
+    void *read_buf = NULL;
+    int read_remaining = 0;
+    int read_state = 0;
+
+    // Completed operations to send replies back to the client
+    std::deque<osd_op_t*> completions;
+
+    // Write state
+    osd_op_t *write_op = NULL;
+    iovec write_iov;
+    msghdr write_msg;
+    void *write_buf = NULL;
+    int write_remaining = 0;
+    int write_state = 0;
+};
+
+class osd_t
+{
+    // config
+
+    int client_queue_depth = 128;
+
+    // fields
+
+    blockstore *bs;
+    ring_loop_t *ringloop;
+
+    int wait_state = 0;
+    int epoll_fd = 0;
+    int listen_fd = 0;
+    ring_consumer_t consumer;
+
+    std::string bind_address;
+    int bind_port, listen_backlog;
+
+    std::unordered_map<int,osd_client_t> clients;
+    std::vector<int> read_ready_clients;
+    std::vector<int> write_ready_clients;
+
+    void loop();
+    int handle_epoll_events();
+    void stop_client(int peer_fd);
+    void read_requests();
+    void handle_read(ring_data_t *data, int peer_fd);
+    void enqueue_op(osd_op_t *cur_op);
+    void send_replies();
+    void make_reply(osd_op_t *op);
+    void handle_send(ring_data_t *data, int peer_fd);
+public:
+    osd_t(blockstore_config_t & config, blockstore *bs, ring_loop_t *ringloop);
+    ~osd_t();
+};
diff --git a/osd_main.cpp b/osd_main.cpp
new file mode 100644
index 00000000..065202cd
--- /dev/null
+++ b/osd_main.cpp
@@ -0,0 +1,27 @@
+#include "osd.h"
+
+int main(int narg, char *args[])
+{
+    if (sizeof(osd_any_op_t) >= OSD_OP_PACKET_SIZE ||
+        sizeof(osd_any_reply_t) >= OSD_REPLY_PACKET_SIZE)
+    {
+        perror("BUG: too small packet size");
+        return 1;
+    }
+    blockstore_config_t config;
+    config["meta_device"] = "./test_meta.bin";
+    config["journal_device"] = "./test_journal.bin";
+    config["data_device"] = "./test_data.bin";
+    ring_loop_t *ringloop = new ring_loop_t(512);
+    blockstore *bs = new blockstore(config, ringloop);
+    osd_t *osd = new osd_t(config, bs, ringloop);
+    while (1)
+    {
+        ringloop->loop();
+        ringloop->wait();
+    }
+    delete osd;
+    delete bs;
+    delete ringloop;
+    return 0;
+}
diff --git a/osd_ops.h b/osd_ops.h
index f2027284..fca97ad1 100644
--- a/osd_ops.h
+++ b/osd_ops.h
@@ -61,8 +61,6 @@ struct __attribute__((__packed__)) osd_op_secondary_rw_t
 struct __attribute__((__packed__)) osd_reply_secondary_rw_t
 {
     osd_reply_header_t header;
-    // buffer size
-    uint64_t len;
 };
 
 // delete object on the secondary OSD
@@ -115,8 +113,6 @@ struct __attribute__((__packed__)) osd_op_secondary_list_t
 struct __attribute__((__packed__)) osd_reply_secondary_list_t
 {
     osd_reply_header_t header;
-    // oid array length
-    uint64_t len;
 };
 
 union osd_any_op_t
@@ -138,7 +134,3 @@ union osd_any_reply_t
     osd_reply_secondary_stabilize_t sec_stabilize;
     osd_reply_secondary_list_t sec_list;
 };
-
-static int size_ok = sizeof(osd_any_op_t) < OSD_OP_PACKET_SIZE &&
-    sizeof(osd_any_reply_t) < OSD_REPLY_PACKET_SIZE
-    ? (perror("BUG: too small packet size"), 0) : 1;