make lmdb's map_size configurable (fix #628)

Cargo.lock

@@ -1340,6 +1340,7 @@ dependencies = [
  "async-trait",
  "base64 0.21.3",
  "blake2",
+ "bytesize",
  "err-derive",
  "futures",
  "futures-util",

Cargo.nix

@@ -33,7 +33,7 @@ args@{
   ignoreLockHash,
 }:
 let
-  nixifiedLockHash = "b958f9aca0ee3fb1f7b52b15508132d0a96480a7f43f83e0da6609c0fe1812ef";
+  nixifiedLockHash = "c5e95ea3fbf4a23e07fe76a8c8886e4eb4a7c95b2d9ca8fa22fa4d8792b4d29f";
   workspaceSrc = if args.workspaceSrc == null then ./. else args.workspaceSrc;
   currentLockHash = builtins.hashFile "sha256" (workspaceSrc + /Cargo.lock);
   lockHashIgnored = if ignoreLockHash
@@ -1911,6 +1911,7 @@ in
       async_trait = (buildRustPackages."registry+https://github.com/rust-lang/crates.io-index".async-trait."0.1.73" { profileName = "__noProfile"; }).out;
       base64 = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".base64."0.21.3" { inherit profileName; }).out;
       blake2 = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".blake2."0.10.6" { inherit profileName; }).out;
+      bytesize = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".bytesize."1.3.0" { inherit profileName; }).out;
       err_derive = (buildRustPackages."registry+https://github.com/rust-lang/crates.io-index".err-derive."0.3.1" { profileName = "__noProfile"; }).out;
       futures = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".futures."0.3.28" { inherit profileName; }).out;
       futures_util = (rustPackages."registry+https://github.com/rust-lang/crates.io-index".futures-util."0.3.28" { inherit profileName; }).out;

doc/book/reference-manual/configuration.md

@@ -17,6 +17,7 @@ block_size = 1048576
 
 sled_cache_capacity = 134217728
 sled_flush_every_ms = 2000
+lmdb_map_size = "10T"
 
 replication_mode = "3"
 
@@ -160,6 +161,14 @@ Increase this if sled is thrashing your SSD, at the risk of losing more data in
 of a power outage (though this should not matter much as data is replicated on other
 nodes). The default value, 2000ms, should be appropriate for most use cases.
 
+### `lmdb_map_size`
+
+This parameters can be used to set the map size used by LMDB,
+which is the size of the virtual memory region used for mapping the database file.
+The value of this parameter is the maximum size the metadata database can take.
+This value is not bound by the physical RAM size of the machine running Garage.
+If not specified, it defaults to 1GiB on 32-bit machines and 1TiB on 64-bit machines.
+
 ### `replication_mode`
 
 Garage supports the following replication modes:

src/model/Cargo.toml

@@ -23,6 +23,7 @@ garage_util.workspace = true
 async-trait = "0.1.7"
 arc-swap = "1.0"
 blake2 = "0.10"
+bytesize = "1.2"
 err-derive = "0.3"
 hex = "0.4"
 base64 = "0.21"

src/model/garage.rs

@@ -121,11 +121,22 @@ impl Garage {
 			// ---- LMDB DB ----
 			#[cfg(feature = "lmdb")]
 			"lmdb" | "heed" => {
+				use std::convert::TryInto;
 				db_path.push("db.lmdb");
 				info!("Opening LMDB database at: {}", db_path.display());
 				std::fs::create_dir_all(&db_path)
 					.ok_or_message("Unable to create LMDB data directory")?;
-				let map_size = garage_db::lmdb_adapter::recommended_map_size();
+				let map_size = match &config.lmdb_map_size {
+					None => garage_db::lmdb_adapter::recommended_map_size(),
+					Some(v) => {
+						let v: usize = v
+							.parse::<bytesize::ByteSize>()
+							.ok()
+							.and_then(|x| x.as_u64().try_into().ok())
+							.ok_or_message("invalid value for `lmdb_map_size`")?;
+						v - (v % 4096)
+					}
+				};
 
 				use db::lmdb_adapter::heed;
 				let mut env_builder = heed::EnvOpenOptions::new();
@@ -142,6 +153,7 @@ impl Garage {
 							"OutOfMemory error while trying to open LMDB database. This can happen \
 							if your operating system is not allowing you to use sufficient virtual \
 							memory address space. Please check that no limit is set (ulimit -v). \
+							You may also try to set a smaller `lmdb_map_size` configuration parameter. \
 							On 32-bit machines, you should probably switch to another database engine.".into()))
 					}
 					x => x.ok_or_message("Unable to open LMDB DB")?,

src/util/config.rs

@@ -72,6 +72,10 @@ pub struct Config {
 	#[serde(default = "default_sled_flush_every_ms")]
 	pub sled_flush_every_ms: u64,
 
+	/// LMDB map size
+	#[serde(default)]
+	pub lmdb_map_size: Option<String>,
+
 	// -- APIs
 	/// Configuration for S3 api
 	pub s3_api: S3ApiConfig,