Many improvements on ring/replication and its configuration:

- Explicit "replication_mode" configuration parameters that takes
  either "none", "2" or "3" as values, instead of letting user configure
  replication factor themselves. These are presets whose corresponding
  replication/quorum values can be found in replication/mode.rs

- Explicit support for single-node and two-node deployments
  (number of nodes must be at least "replication_mode", with "none"
  we can have only one node)

- Ring is now stored much more compactly with 256*8 + n*32 bytes,
  instead of 256*32 bytes

- Support for gateway-only nodes that do not store data
  (these nodes still need a metadata_directory to store the list
  of bucket and keys since those are stored on all nodes; it also
  technically needs a data_directory to start but it will stay
  empty unless we have bugs)

1 files changed, 18 insertions, 28 deletions

diff --git a/src/util/config.rs b/src/util/config.rs
index 093b3850..46b918a9 100644
--- a/src/util/config.rs
+++ b/src/util/config.rs
@@ -15,6 +15,17 @@ pub struct Config {
 	/// Path where to store data. Can be slower, but need higher volume
 	pub data_dir: PathBuf,
 
+	/// Size of data blocks to save to disk
+	#[serde(default = "default_block_size")]
+	pub block_size: usize,
+
+	/// Replication mode. Supported values:
+	/// - none, 1 -> no replication
+	/// - 2 -> 2-way replication
+	/// - 3 -> 3-way replication
+	// (we can add more aliases for this later)
+	pub replication_mode: String,
+
 	/// Address to bind for RPC
 	pub rpc_bind_addr: SocketAddr,
 
@@ -26,6 +37,13 @@ pub struct Config {
 	/// Consul service name to use
 	pub consul_service_name: Option<String>,
 
+	/// Configuration for RPC TLS
+	pub rpc_tls: Option<TlsConfig>,
+
+	/// Max number of concurrent RPC request
+	#[serde(default = "default_max_concurrent_rpc_requests")]
+	pub max_concurrent_rpc_requests: usize,
+
 	/// Sled cache size, in bytes
 	#[serde(default = "default_sled_cache_capacity")]
 	pub sled_cache_capacity: u64,
@@ -34,28 +52,6 @@ pub struct Config {
 	#[serde(default = "default_sled_flush_every_ms")]
 	pub sled_flush_every_ms: u64,
 
-	/// Max number of concurrent RPC request
-	#[serde(default = "default_max_concurrent_rpc_requests")]
-	pub max_concurrent_rpc_requests: usize,
-
-	/// Size of data blocks to save to disk
-	#[serde(default = "default_block_size")]
-	pub block_size: usize,
-
-	#[serde(default = "default_control_write_max_faults")]
-	pub control_write_max_faults: usize,
-
-	/// How many nodes should hold a copy of meta data
-	#[serde(default = "default_replication_factor")]
-	pub meta_replication_factor: usize,
-
-	/// How many nodes should hold a copy of data
-	#[serde(default = "default_replication_factor")]
-	pub data_replication_factor: usize,
-
-	/// Configuration for RPC TLS
-	pub rpc_tls: Option<TlsConfig>,
-
 	/// Configuration for S3 api
 	pub s3_api: ApiConfig,
 
@@ -106,12 +102,6 @@ fn default_max_concurrent_rpc_requests() -> usize {
 fn default_block_size() -> usize {
 	1048576
 }
-fn default_replication_factor() -> usize {
-	3
-}
-fn default_control_write_max_faults() -> usize {
-	1
-}
 
 /// Read and parse configuration
 pub fn read_config(config_file: PathBuf) -> Result<Config, Error> {