Replication =================================== Seaweed-FS can support replication. The replication is implemented not on file level, but on volume level. How to use ################################### Basically, the way it works is: 1. start weed master, and optionally specify the default replication type .. code-block:: bash ./weed master -defaultReplicationType=001 2. start volume servers as this: .. code-block:: bash ./weed volume -port=8081 -dir=/tmp/1 -max=100 ./weed volume -port=8082 -dir=/tmp/2 -max=100 ./weed volume -port=8083 -dir=/tmp/3 -max=100 Submitting, Reading, Deleting files has the same steps. The meaning of replication type ################################### *Note: This subject to change.* +-----+---------------------------------------------------------------------------+ |000 |no replication, just one copy | +-----+---------------------------------------------------------------------------+ |001 |replicate once on the same rack | +-----+---------------------------------------------------------------------------+ |010 |replicate once on a different rack in the same data center | +-----+---------------------------------------------------------------------------+ |100 |replicate once on a different data center | +-----+---------------------------------------------------------------------------+ |200 |replicate twice on two other different data center | +-----+---------------------------------------------------------------------------+ |110 |replicate once on a different rack, and once on a different data center | +-----+---------------------------------------------------------------------------+ |... |... | +-----+---------------------------------------------------------------------------+ So if the replication type is xyz +-------+--------------------------------------------------------+ |**x** |number of replica in other data centers | +-------+--------------------------------------------------------+ |**y** |number of replica in other racks in the same data center| +-------+--------------------------------------------------------+ |**z** |number of replica in other servers in the same rack | +-------+--------------------------------------------------------+ x,y,z each can be 0, 1, or 2. So there are 9 possible replication types, and can be easily extended. Each replication type will physically create x+y+z+1 copies of volume data files. Example topology configuration ################################### The Seaweed-FS master server tries to read the default topology configuration file are read from /etc/weedfs/weedfs.conf, if it exists. The topology setting to configure data center and racks file format is as this. .. code-block:: xml 192.168.1.1 192.168.1.2 192.168.1.3 192.168.1.4 Allocate File Key on specific data center Volume servers can start with a specific data center name. .. code-block:: bash weed volume -dir=/tmp/1 -port=8080 -dataCenter=dc1 weed volume -dir=/tmp/2 -port=8081 -dataCenter=dc2 Or the master server can determine the data center via volume server's IP address and settings in weed.conf file. Now when requesting a file key, an optional "dataCenter" parameter can limit the assigned volume to the specific data center. For example, this specify .. code-block:: bash http://localhost:9333/dir/assign?dataCenter=dc1