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Diffstat (limited to 'docs/distributed_filer.rst')
| -rw-r--r-- | docs/distributed_filer.rst | 31 |
1 files changed, 21 insertions, 10 deletions
diff --git a/docs/distributed_filer.rst b/docs/distributed_filer.rst index 29055c73e..ad9f85d5c 100644 --- a/docs/distributed_filer.rst +++ b/docs/distributed_filer.rst @@ -10,7 +10,11 @@ However, no SPOF is a must-have requirement for many projects. Luckily, SeaweedFS is so flexible that we can use a completely different way to manage file metadata. -This distributed filer uses Cassandra to store the metadata. +This distributed filer uses Redis or Cassandra to store the metadata. + +Redis Setup +##################### +No setup required. Cassandra Setup ##################### @@ -37,7 +41,14 @@ For production server, you would want to set replication_factor to 3. Sample usage ##################### -To start a weed filer in distributed mode: +To start a weed filer in distributed mode with Redis: + +.. code-block:: bash + + # assuming you already started weed master and weed volume + weed filer -redis.server=localhost:6379 + +To start a weed filer in distributed mode with Cassandra: .. code-block:: bash @@ -57,8 +68,8 @@ Now you can add/delete files Limitation ############ -List sub folders and files are not supported because Cassandra does not support -prefix search. +List sub folders and files are not supported because Redis or Cassandra +does not support prefix search. Flat Namespace Design ############ @@ -73,16 +84,16 @@ A flat namespace would take more space because the parent directories are repeatedly stored. But disk space is a lesser concern especially for distributed systems. -The Cassandra table is a simple file_full_path ~ file_id mapping. Actually -it is a file_full_path ~ list_of_file_ids mapping with the hope to support -easy file appending for streaming files. +So either Redis or Cassandra is a simple file_full_path ~ file_id mapping. +(Actually Cassandra is a file_full_path ~ list_of_file_ids mapping +with the hope to support easy file appending for streaming files.) Complexity ################### For one file retrieval, the full_filename=>file_id lookup will be O(logN) -using Cassandra. But very likely the one additional network hop would -take longer than the Cassandra internal lookup. +using Redis or Cassandra. But very likely the one additional network hop would +take longer than the actual lookup. Use Cases ######################### @@ -93,7 +104,7 @@ read files via HTTP POST directly. Future ################### -SeaweedFS can support additional distributed databases. It will be better +SeaweedFS can support other distributed databases. It will be better if that database can support prefix search, in order to list files under a directory. |