# Storage-System

Purpose and description to be added

## Deprecated Metadata Backend

Starting with ocis version 3.0.0, the default backend for metadata switched to messagepack. If the setting `STORAGE_SYSTEM_OCIS_METADATA_BACKEND` has not been defined manually, the backend will be migrated to `messagepack` automatically. Though still possible to manually configure `xattrs`, this setting should not be used anymore as it will be removed in a later version.

## Caching

The `storage-system` service caches file metadata via the configured store in `STORAGE_SYSTEM_CACHE_STORE`. Possible stores are:
  -   `memory`: Basic in-memory store and the default.
  -   `redis-sentinel`: Stores data in a configured Redis Sentinel cluster.
  -   `nats-js-kv`: Stores data using key-value-store feature of [nats jetstream](https://docs.nats.io/nats-concepts/jetstream/key-value-store)
  -   `noop`: Stores nothing. Useful for testing. Not recommended in production environments.
  -   `ocmem`: Advanced in-memory store allowing max size. (deprecated)
  -   `redis`: Stores data in a configured Redis cluster. (deprecated)
  -   `etcd`: Stores data in a configured etcd cluster. (deprecated)
  -   `nats-js`: Stores data using object-store feature of [nats jetstream](https://docs.nats.io/nats-concepts/jetstream/obj_store) (deprecated)

Other store types may work but are not supported currently.

Note: The service can only be scaled if not using `memory` store and the stores are configured identically over all instances!

Note that if you have used one of the deprecated stores, you should reconfigure to one of the supported ones as the deprecated stores will be removed in a later version.

Store specific notes:
  -   When using `redis-sentinel`, the Redis master to use is configured via e.g. `OCIS_CACHE_STORE_NODES` in the form of `<sentinel-host>:<sentinel-port>/<redis-master>` like `10.10.0.200:26379/mymaster`.
  -   When using `nats-js-kv` it is recommended to set `OCIS_CACHE_STORE_NODES` to the same value as `OCIS_EVENTS_ENDPOINT`. That way the cache uses the same nats instance as the event bus.
  -   When using the `nats-js-kv` store, it is possible to set `OCIS_CACHE_DISABLE_PERSISTENCE` to instruct nats to not persist cache data on disc.