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| -rw-r--r-- | doc/book/reference-manual/configuration.md | 43 |
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diff --git a/doc/book/reference-manual/configuration.md b/doc/book/reference-manual/configuration.md index 6db12568..97da0e0e 100644 --- a/doc/book/reference-manual/configuration.md +++ b/doc/book/reference-manual/configuration.md @@ -9,6 +9,8 @@ Here is an example `garage.toml` configuration file that illustrates all of the metadata_dir = "/var/lib/garage/meta" data_dir = "/var/lib/garage/data" +db_engine = "lmdb" + block_size = 1048576 replication_mode = "3" @@ -71,6 +73,47 @@ This folder can be placed on an HDD. The space available for `data_dir` should be counted to determine a node's capacity when [adding it to the cluster layout](@/documentation/cookbook/real-world.md). +### `db_engine` (since `v0.8.0`) + +By default, Garage uses the Sled embedded database library +to store its metadata on-disk. Since `v0.8.0`, Garage can use alternative storage backends as follows: + +| DB engine | `db_engine` value | Database path | +| --------- | ----------------- | ------------- | +| [Sled](https://sled.rs) | `"sled"` | `<metadata_dir>/db/` | +| [LMDB](https://www.lmdb.tech) | `"lmdb"` | `<metadata_dir>/db.lmdb/` | +| [Sqlite](https://sqlite.org) | `"sqlite"` | `<metadata_dir>/db.sqlite` | + +Performance characteristics of the different DB engines are as follows: + +- Sled: the default database engine, which tends to produce + large data files and also has performance issues, especially when the metadata folder + is on a traditionnal HDD and not on SSD. +- LMDB: the recommended alternative on 64-bit systems, + much more space-efficiant and slightly faster. Note that the data format of LMDB is not portable + between architectures, so for instance the Garage database of an x86-64 + node cannot be moved to an ARM64 node. Also note that, while LMDB can technically be used on 32-bit systems, + this will limit your node to very small database sizes due to how LMDB works; it is therefore not recommended. +- Sqlite: Garage supports Sqlite as a storage backend for metadata, + however it may have issues and is also very slow in its current implementation, + so it is not recommended to be used for now. + +It is possible to convert Garage's metadata directory from one format to another with a small utility named `convert_db`, +which can be downloaded at the following locations: +[for amd64](https://garagehq.deuxfleurs.fr/_releases/convert_db/amd64/convert_db), +[for i386](https://garagehq.deuxfleurs.fr/_releases/convert_db/i386/convert_db), +[for arm64](https://garagehq.deuxfleurs.fr/_releases/convert_db/arm64/convert_db), +[for arm](https://garagehq.deuxfleurs.fr/_releases/convert_db/arm/convert_db). +The `convert_db` utility is used as folows: + +``` +convert-db -a <input db engine> -i <input db path> \ + -b <output db engine> -o <output db path> +``` + +Make sure to specify the full database path as presented in the table above, +and not just the path to the metadata directory. + ### `block_size` Garage splits stored objects in consecutive chunks of size `block_size` |