This is a consolidation effort, avoiding usage
of naked strings in codebase. Whenever possible
use constants which can be repurposed elsewhere.
This also fixes `goconst ./...` reported issues.
This is important in a distributed setup, where the server hosting the
first disk formats a fresh setup. Sorting ensures that all servers
arrive at the same 'first' server.
Note: This change doesn't protect against different disk arguments
with some disks being same across servers.