Storage efficiency translates in many cases into money. Three replicas would use more disk space compared to 4+2 EC policy and hence will have different economic.
With that said, it's important to keep in mind that EC effects the availability of the system ad the ratio will determine the number of failures that the bucket would be able to tolerate, as well as the time it will take to rebuild the data.
Additional information on data resiliency can be found in the following article
Changing the default data resiliency policy can be done with the following steps
- Go to buckets > bucket page
- In bucket policies tab, go to Data resiliency and click on “Edit Data Resiliency”
- By default, the selected resiliency type is replication. To change the selected type, click on Erasure coding radio button.
- To configure a different number of replicas or fragments click on “Advanced Settings” and set the wanted number.
In case, you want to change to a more efficient policy, we recommend on 4 +2 policy, which will two failures, while the rebuild time is relatively fast.
An advanced mode is also available, for a customized erasure coding setting, while the information about the fault tolerance and rebuild efforts provided for any selected combination.
The minimum number of replications is 1 (not recommended due 0 failure tolerance)
The Minimum number of fragments is 1+1.
The sum of data+parity could be 256 maximum.
- Each setting will change the summary details according to the desired configuration, pay attention to any alerts that might appear due to incompatible policies.
- Once configurations are set, click on “Done”
- The bucket status will most likely be changed to “rebuilding” while all object files are changing according to the new data resiliency policy.
- All current data resiliency details will appear in the collapsible section in bucket policies tab.