If STANDARD storage class is set before starting up Minio server,
but x-amz-storage-class metadata field is not set in a PutObject
request, Minio server defaults to N/2 data and N/2 parity disks.
This PR changes the behaviour to use data and parity disks set in
STANDARD storage class, even if x-amz-storage-class metadata
field is not present in PutObject requests.
- Add storage class metadata validation for request header
- Change storage class header values to be consistent with AWS S3
- Refactor internal method to take only the reqd argument
This adds configurable data and parity options on a per object
basis. To use variable parity
- Users can set environment variables to cofigure variable
parity
- Then add header x-amz-storage-class to putobject requests
with relevant storage class values
Fixes#4997
