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How to use
Basically, the way it works is:
- start weed master, and optionally specify the default replication type
- ./weed master -defaultReplication=001
- start volume servers as this:
- ./weed volume -port=8081 -dir=/tmp/1 -max=100 -mserver="master_address:9333" -dataCenter=dc1 -rack=rack1
- ./weed volume -port=8082 -dir=/tmp/2 -max=100 -mserver="master_address:9333" -dataCenter=dc1 -rack=rack1
On another rack,
- ./weed volume -port=8081 -dir=/tmp/1 -max=100 -mserver="master_address:9333" -dataCenter=dc1 -rack=rack2
- ./weed volume -port=8082 -dir=/tmp/2 -max=100 -mserver="master_address:9333" -dataCenter=dc1 -rack=rack2
No change to Submitting, Reading, and Deleting files.
The meaning of replication type
Note: This subject to change.
| Value | Meaning |
|---|---|
| 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
| Column | Meaning |
|---|---|
| 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.
Allocate File Key on specific data center
Now when requesting a file key, an optional "dataCenter" parameter can limit the assigned volume to the specific data center. For example, this specify
- http://localhost:9333/dir/assign?dataCenter=dc1
