diff --git a/server/texture-sync-server/src/model/mod.rs b/server/texture-sync-server/src/model/mod.rs
index 4737e34..e06b579 100644
--- a/server/texture-sync-server/src/model/mod.rs
+++ b/server/texture-sync-server/src/model/mod.rs
@@ -3,6 +3,8 @@
 #![allow(unused_variables)]
 #![allow(dead_code)]
 
+use std::io;
+
 mod sha256;
 pub use sha256::Sha256;
 
@@ -18,3 +20,14 @@ pub struct Texture {
     pub resolution: (usize, usize),
     pub texture_hash: Sha256,
 }
+
+pub enum ReplaceTextureStatus {
+    // Done.
+    Ok,
+
+    // Call Again With Texture Binary
+    NeedTextureData(Sha256),
+
+    // Name or id already in use
+    Conflict,
+}
diff --git a/server/texture-sync-server/src/persistency/mod.rs b/server/texture-sync-server/src/persistency/mod.rs
index c4f0bde..992e696 100644
--- a/server/texture-sync-server/src/persistency/mod.rs
+++ b/server/texture-sync-server/src/persistency/mod.rs
@@ -70,47 +70,85 @@ impl DataStore {
         }
     }
 
-    pub fn insert(&mut self, tex: Texture) -> bool {
+    /// * `data` The content of the texture file, if available.
+    pub fn insert(
+        &mut self,
+        tex: Texture,
+        data: Option<Arc<Vec<u8>>>,
+    ) -> io::Result<ReplaceTextureStatus> {
+        use io::Write;
+
         // Check for collisions
-        let pos = self
+        if self
             .texture
             .iter()
-            .position(|e| e.id == tex.id || e.name == tex.name);
-        match pos {
-            // Texture with same name or id is already stored
-            Some(_) => false,
+            .find(|e| e.id == tex.id || e.name == tex.name)
+            .is_some()
+        {
+            // Name or id already in use
+            Ok(ReplaceTextureStatus::Conflict)
+        } else {
             // Insert it
-            None => {
+            if self.has_hash(&tex.texture_hash)? {
                 self.texture.push(tex);
-                true
+                Ok(ReplaceTextureStatus::Ok)
+            } else {
+                match data {
+                    None => Ok(ReplaceTextureStatus::NeedTextureData(tex.texture_hash)),
+                    Some(blob) => {
+                        let mut tmp_image_path = self.data_dir.clone();
+                        tmp_image_path.push("textures");
+                        tmp_image_path.push(format!(
+                            "{}_new",
+                            tex.texture_hash.create_hex_string().to_lowercase()
+                        ));
+                        let mut final_image_path = self.data_dir.clone();
+                        final_image_path.push("textures");
+                        final_image_path.push(tex.texture_hash.create_hex_string().to_lowercase());
+                        {
+                            let mut writer = fs::File::create(&tmp_image_path)?;
+                            writer.write_all(&blob)?;
+                        }
+                        fs::rename(tmp_image_path, final_image_path)?;
+                        Ok(ReplaceTextureStatus::Ok)
+                    }
+                }
             }
         }
     }
 
     pub fn by_name<'a>(&'a self, name: &str) -> Option<&'a Texture> {
-        let pos = self.texture.iter().position(|e| e.name == name);
-        match pos {
-            Some(idx) => Some(self.texture.get(idx).unwrap()),
-            None => None,
-        }
+        self.texture.iter().find(|e| e.name == name)
     }
 
     pub fn by_id<'a, 'b>(&'a self, id: &'b str) -> Option<&'a Texture> {
-        let pos = self.texture.iter().position(|e| e.id == id);
-        match pos {
-            Some(idx) => Some(self.texture.get(idx).unwrap()),
-            None => None,
-        }
+        self.texture.iter().find(|e| e.id == id)
     }
 
-    pub fn has_hash(&self, hash: &Sha256) -> bool {
-        // TODO What is the purpose of this function?
-        // Currently checks for textures in the list with the given hash.
-        // Should it check for an existing image file instead?
-        self.texture
-            .iter()
-            .position(|e| &e.texture_hash == hash)
-            .is_some()
+    /// Check if the texture, given by hash, physically exists on the file system.
+    pub fn has_hash(&self, hash: &Sha256) -> io::Result<bool> {
+        let mut texture_path = self.data_dir.clone();
+        texture_path.push("textures");
+        texture_path.push(hash.create_hex_string().to_lowercase());
+        match texture_path.metadata() {
+            Ok(meta) => {
+                if meta.is_file() {
+                    Ok(true)
+                } else {
+                    Err(io::Error::new(
+                        io::ErrorKind::Other,
+                        format!("{:?} exists but is not a regular file.", texture_path),
+                    ))
+                }
+            }
+            Err(e) => {
+                if e.kind() == io::ErrorKind::NotFound {
+                    Ok(false)
+                } else {
+                    Err(e)
+                }
+            }
+        }
     }
 
     pub fn get_texture_file(&mut self, hash: &Sha256) -> TextureFileResult {
diff --git a/server/texture-sync-server/src/protocol/error.rs b/server/texture-sync-server/src/protocol/error.rs
index daecb0d..32e1ac3 100644
--- a/server/texture-sync-server/src/protocol/error.rs
+++ b/server/texture-sync-server/src/protocol/error.rs
@@ -1,12 +1,5 @@
 use crate::model::*;
 
-pub enum ReplaceTextureStatus {
-    // Call Again With Texture Binary
-    NeedTextureData(Sha256),
-    // Done.
-    Ok,
-}
-
 pub type ProtocolResult<T> = Result<T, ProtocolError>;
 pub enum ProtocolError {
     BadRequest(String),
diff --git a/server/texture-sync-server/src/protocol/implementation/listen_forever.rs b/server/texture-sync-server/src/protocol/implementation/listen_forever.rs
index 7177cb1..7880f01 100644
--- a/server/texture-sync-server/src/protocol/implementation/listen_forever.rs
+++ b/server/texture-sync-server/src/protocol/implementation/listen_forever.rs
@@ -109,6 +109,10 @@ where
                                         panic!("Contract Violation: handler must not return NeedTextureData \
                                         when data is given.");
                                     }
+                                    Ok(ReplaceTextureStatus::Conflict) => {
+                                        connection
+                                            .send(&Package::Error(409, "Conflict".to_string()))?;
+                                    }
                                     Err(err) => {
                                         connection.send(&Package::from(err))?;
                                     }
@@ -125,6 +129,9 @@ where
                             }
                         }
                     }
+                    Ok(ReplaceTextureStatus::Conflict) => {
+                        connection.send(&Package::Error(409, "Conflict".to_string()))?;
+                    }
                     Err(err) => {
                         connection.send(&Package::from(err))?;
                     }