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Re: in /etc/network/interfaces: "auto" vs "allow-hotplug"




On Sat, Sep 23, 2017 at 08:56:49PM -0700, Rick Thomas wrote:
> I have two machines (out of a group of ten) that will not bring up their ethernet interface at boot time if the interfaces is of type “allow-hotplug”.  When I change that to “auto” the interface comes up at boot with no problem…
> 
> The remaining eight machines have no problem with allow-hotplug. (which is the default as setup by the d-i)

The basic difference is the order in which services get loaded at
boot time, and whether the services wait for something, or just go.

An interface marked "auto" will be waited-for by services that are
configured to wait for interfaces to be up.  E.g. mounting NFS file
systems, or starting an NFS server.

An interface marked "allow-hotplug" is considered nonessential or
transient, and the core OS services won't wait for it before starting.