Re: DE and hot-swap disk caddies

Andre Hedrick (
Wed, 27 Mar 2002 16:23:34 -0800 (PST)

On Wed, 27 Mar 2002, Erik Andersen wrote:

> On Wed Mar 27, 2002 at 03:57:48PM -0800, Andre Hedrick wrote:
> > > If you really want to build in IDE hot swap support, I demand it comes
> > > with a warning: Enabling this option will probably destroy your harddisks
> > > and your chipset. Feel free to continue, but don't blame us.
> >
> > FYI, there was almost a witch hunt when I went into T13 with a SCA4ATA
> > proposal. You understand the issue and I am glad it was you and not me to
> > have to bang this drum. Thanks.
> Ok. How about my laptop? I have an ATAPI zip drive I can plug
> in instead of a second battery. It is the only device on the
> second IDE bus (hdc). In windows there is a little hotplug
> utility thing one runs before unplugging the zip drive. In Linux
> I currently have to reboot if I want the ide-floppy driver to see
> the device... I'm willing to bet that Dell has done mysterious
> stuff to make the electrical part work. It would sure be nice if
> I could ask the ide driver to kindly re-scan for /dev/hdc now.
> Is whatever windows is doing when I hotplug my zip drive somehow
> unsafe, such that supporting the same functionality on Linux is
> somehow a Bad Thing(tm)?

That is not an ATA interface, it is Media Bay transport.
I will bet you they have not on a native 40-pin header that a ribbon
connects. Everyone is thinking it is easy, but it is not.

There was one company how got it correct, but I do not know if they are
still around. The solution is not CHEAP, it requires total HOST vender
unique callers and special state diagrams. Also this was a true
Master/Slave pair solution, the hook was it broke the timing skews on the
buss. Thus Ultra33 or mode 2 as the limit.


Andre Hedrick
LAD Storage Consulting Group

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