I looked at various post as well as v8 of erpnext but cannot find rack/bin.
Whereas it is mentioned at https://erpnext.org/docs/current/models/stock/bin
So question is whether it is implemented or not.
If not, when it is expected and what is the custom recommended way to implement it. Thanks!
The “Bin” you are referred in the link is an internal document to maintain the balances for a combination of item_code and warehouse.
Whether what you are finding as Bin/Rack is implemented through Warehouse itself. In ERPNext, Warehouse is maintained in a tree structure. So, you create warehouses for Rack as well under main Warehouse.