Why Is Stacking Needed; Default Stacking Values - Dell PowerConnect 8024 User Configuration Manual

If your switch stack performs VLAN routing, another way to take advantage of
NSF is to configure multiple "best paths" to the same destination on different
stack members. If a unit fails, the forwarding plane removes Equal Cost
Multipath (ECMP) next hops on the failed unit from all unicast forwarding
table entries. If the cleanup leaves a route without any next hops, the route is
deleted. The forwarding plane only selects ECMP next hops on surviving
units. For this reason, try to distribute links providing ECMP paths across
multiple stack units.

Why is Stacking Needed?

Stacking increases port count without requiring additional configuration. If
you have multiple PowerConnect switches, stacking them helps make
management of the switches easier because you configure the stack as a single
unit and do not need to configure individual switches.

Default Stacking Values

Stacking is always enabled. By default, the 10G SFP+ ports are in Ethernet
mode and must be configured to be used as stacking ports.
NSF is enabled by default. You can disable NSF in order to redirect the CPU
resources consumed by data checkpointing. Checkpointing only occurs when
a backup unit is elected, so there is no need to disable the NSF feature on a
standalone switch. When a new unit is added to the stack, the new unit takes
the configuration of the stack, including the NSF setting.
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Managing a Switch Stack