diff --git a/disk/src/gen.rs b/disk/src/gen.rs
new file mode 100644
index 0000000..bc9baf5
--- /dev/null
+++ b/disk/src/gen.rs
@@ -0,0 +1,89 @@
+#[allow(unused_imports)]
+use tracing::{error, warn, info, debug, trace};
+use err::Error;
+use std::task::{Context, Poll};
+use std::future::Future;
+use futures_core::Stream;
+use futures_util::future::FusedFuture;
+use futures_util::{pin_mut, StreamExt};
+use std::pin::Pin;
+use tokio::io::AsyncRead;
+use tokio::fs::File;
+use bytes::{Bytes, BytesMut, BufMut, Buf};
+use std::path::PathBuf;
+use bitshuffle::bitshuffle_compress;
+use netpod::ScalarType;
+use std::sync::Arc;
+use crate::gen::Shape::Scalar;
+
+pub async fn gen_test_data() -> Result<(), Error> {
+    let mut ensemble = Ensemble {
+        nodes: vec![],
+        channels: vec![],
+    };
+    {
+        let chan = Channel {
+            backend: "test".into(),
+            keyspace: 3,
+            name: "wave1".into(),
+            scalar_type: ScalarType::F32,
+            shape: Shape::Wave(42),
+            time_spacing: 420,
+        };
+        ensemble.channels.push(chan);
+    }
+    let direnv = DirEnv {
+        path: "./tmpdata".into(),
+    };
+    let direnv = Arc::new(direnv);
+    let node1 = Node {
+        host: "localhost".into(),
+        port: 7780,
+        direnv: direnv.clone(),
+    };
+    ensemble.nodes.push(node1);
+    for node in &ensemble.nodes {
+        gen_node(node, &ensemble).await?;
+    }
+    Ok(())
+}
+
+struct Ensemble {
+    nodes: Vec<Node>,
+    channels: Vec<Channel>,
+}
+
+struct DirEnv {
+    path: PathBuf,
+}
+
+struct Node {
+    host: String,
+    port: u16,
+    direnv: Arc<DirEnv>,
+}
+
+impl Node {
+    fn name(&self) -> String {
+        format!("{}:{}", self.host, self.port)
+    }
+}
+
+enum Shape {
+    Scalar,
+    Wave(usize),
+}
+
+struct Channel {
+    keyspace: u8,
+    backend: String,
+    name: String,
+    scalar_type: ScalarType,
+    shape: Shape,
+    time_spacing: u64,
+}
+
+async fn gen_node(node: &Node, ensemble: &Ensemble) -> Result<(), Error> {
+    tokio::fs::create_dir_all(&node.direnv.path).await?;
+    Ok(())
+}
diff --git a/disk/src/lib.rs b/disk/src/lib.rs
index ad2523a..ece88f1 100644
--- a/disk/src/lib.rs
+++ b/disk/src/lib.rs
@@ -1,20 +1,20 @@
 pub mod agg;
+pub mod gen;
 
 #[allow(unused_imports)]
 use tracing::{error, warn, info, debug, trace};
 use err::Error;
 use std::task::{Context, Poll};
-use std::pin::Pin;
-use tokio::io::AsyncRead;
-use tokio::fs::File;
 use std::future::Future;
 use futures_core::Stream;
 use futures_util::future::FusedFuture;
 use futures_util::{pin_mut, StreamExt};
-use bytes::{Bytes, BytesMut, BufMut, Buf};
+use std::pin::Pin;
+use tokio::io::AsyncRead;
+use tokio::fs::File;
+use bytes::{Bytes, BytesMut, Buf};
 use std::path::PathBuf;
 use bitshuffle::bitshuffle_decompress;
-use async_channel::bounded;
 use netpod::ScalarType;