How stacking works is 2 stacked switches?

Hi,

If device A is connected to switch A, and switch A dies - well then device A will loose access to the network.
If device A is connected to switch A, and cable between them fails then device A will loose access to the network.

There is nothing you can do to prevent this and that is OK because high availability is not about end devices. It is about creating a resilient network to allow important devices to have high availability. Devices such as: servers, storage devices, switches, routers, etc.

A common way to create this high availability is through a combination of stacking and LAG (bonding). For example: I have a stack of two switches. I connect a server to the stack. The connection a done via a LAG of two cables, so that:
- One cable is going from the server to switch 1 in the stack.
- The other cable is going from the server to switch 2 in the stack.

This is called making a LAG across the stack. This is possible to do as the switches in the stack are acting as one unit (like you mentioned yourself). Now, your server has high availability. If switch 1 in the stack dies, the server will still have connection to the network via switch 2. Same scenario if one of the cables fail. This high availability becomes even higher if you stack, say 4 switches, and then then make a 4 cable LAG (across the stack) to your server.

Now, all of this requires two things:
1. The device that connects to the stack is capable of configuring LAGs.
2. That the device connecting to the stack has several NICs.

End devices only has one entry point to the network. If that entry point fails (cable failure or switch failure) then that end device will loose connection. There is nothing you can do about that. If the device is really important, be sure to make LAGs and connect to a stack if possible.

I hope that answered your question.

Cheers