[lug] NIC fact/fiction

Ian S. Nelson nelson_ at attglobal.net
Sat Aug 5 08:31:00 MDT 2000

Brian Jarrett wrote:

> While it is definitely safer to make connections of any sort when everything
> is powered down, it is just not practical in a lot of cases.  Also, much
> technology is being produced around the idea of "hot-plugging" capability
> (USB, SCSI drives, Redundant Power Supplies, etc.)

With a NIC it really doesn't make any sense.  You have to power down the host,
the since the hub is electric you have to down it, essentially killing your
network to add one machine.  You can look at the hardware, memory devices
aside, most of it won't be adversly affected by being yanked or plugged in on
the fly, including processors.   They won't usually work but there isn't
anything about the process that is damaging, I don't do it and wouldn't
recommend it but it's not something to fear, powering up or powering off
essentially equates to pulling or plugging in a part.

I'm working on a product at work and the manufacturer of a test board has us
pull jumpers and push them on n mid-flight.  I'm not saying it's a practice you
should start but I wouldn't worry about it, the hardware usually won't break.

> PS/2 ports used to require the system to be powered down before
> connecting/disconnecting devices, but most other peripheral connections do
> not require you to power down the computer.  Regarding most peripherals, I
> will only power them on once it is connected to the computer.  Bringing the
> computer down every time I connect a device would be an admin headache
> (especially when the machines are servers!)
> Brian

PS/2 devices need the BIOS to start up the controller when you boot.  You could
write a smart driver for Linux (in theory) that would let you hot plug PS/2
mice and keyboards.  What happens is the BIOS runs tests, tickles the PS/2
controller which is going to determine if a keyboard and or mouse is plugged in
and properly initialize that hardware if it is.  It's only done at boot so if
you plug in afterwards the device won't talk.  I'm not an expert at PS/2
periphs but depending on how they work there could be a chip in the part that
needs to be initialized or run some code or it could be that the PS/2
controller just ignores "dead ports" once it determins that there isn't a
device there.  Either way, you could make it work under linux.

Ian S. Nelson                                           __o
Nelson_ at attglobal.net.NOSPAM                            \<,
                                                      ()/ ()

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