Loki persistence configuration

How does loki store data ?
what is the configuration options ?
the example config seem to keep only 15 minutes :

ingester:
  lifecycler:
    address: 127.0.0.1
    ring:
      kvstore:
        store: inmemory
      replication_factor: 1
  chunk_idle_period: 15m

schema_config:
  configs:
  - from: 2018-04-15
    store: boltdb
    object_store: filesystem
    schema: v9
    index:
      prefix: index_
      period: 168h

storage_config:
  boltdb:
    directory: /loki/index

  filesystem:
    directory: /loki/chunks

how should it be changed to persist logs on disk over days…

thanks.