What are hard and soft zoning?

Hard zoning is zoning which is implemented in hardware. Soft zoning is zoning which is implemented in software.

Hard zoning physically blocks access to a zone from any device outside of the zone.

Soft zoning uses filtering implemented in fibre channel switches to prevent ports from being seen from outside of their assigned zones. The security vulnerability in soft zoning is that the ports are still accessible if the user in another zone correctly guesses the fibre channel address.

Here is the pros and cons of zoning:

1) Soft Zoning 2) Hard Zoning 3) Broadcast Zoning

Soft Zoning : Soft zoning uses the name server to enforce zoning. The World Wide Name (WWN) of the elements enforces the configuration policy.

Pros:- Administrators can move devices to different switch ports without manually reconfiguring
zoning. This is major flexibility to administrator. You don't need to change once you create zone set for particular device connected on switch. You create a zone set on switch and allocate storage to host. You can change any port for device connectivity

Cons:- Devices might be able to spoof the WWN and access otherwise restricted resources.
- Device WWN changes, such as the installation of a new Host Bus Adapter (HBA) card, require
policy modifications.
- Because the switch does not control data transfers, it cannot prevent incompatible HBA
devices from bypassing the Name Server and talking directly to hosts.

Hard Zoning: - Hard Zoning uses the physical fabric port number of a switch to create zones and enforce the policy.

Pros:- This system is easier to create and manage than a long list of element WWNs.
- Switch hardware enforces data transfers and ensures that no traffic goes between
unauthorized zone members.
- Hard zoning provides stronger enforcement of the policy (assuming physical security on the
switch is well established).

Cons:- Moving devices to different switch ports requires policy modifications.

Broadcast Zoning: · Broadcast Zoning has many unique characteristics:
- This traffic allows only one broadcast zone per fabric.
- It isolates broadcast traffic.
- It is hardware-enforced.

 If you ask me how to choose the zoning type then it is based on SAN requirement in your data center environment. But port zoning is more secure but you have to be sure that device is not going to change otherwise every time you change in storage allocation you have to modify your zoning.

Generally use in industry is soft zoning but as i have mentioned soft zoning has many cos. So, it is hard to say which one you should use always. So, analyze your datacenter environment and use proper zoning.
Broadcast zoning uses in large environment where are various fabric domain.

Having said that Zoning can be enforced either port number or WWN number but not both.