[GLLUG] Hot Swap an ATA Hard Drive

[Matt Graham]

On Saturday 15 February 2003 18:18, after a long battle with technology, 
aSe wrote, in a message that should've been posted to the mailing list 
at large:
> Dances With Crows wrote:
>> There are adapters (roughly $25 each) for normal IDE disks; the
>> adapter plugs into the motherboard's IDE interface, you slide the
>> drive into the adapter.  You can't do this with vanilla IDE disks. 
>> (Well, you can try, but you'll probably hork up your system.)
>
> Really, I thought IDE wasn't able at all todo hot-swap. What do these
> "adapters" actually do?

They present an interface to the motherboard IDE controllers that always 
looks like an IDE disk of some type, since they have 2 IDE plugs on 
them:  1 for the motherboard IDE cable, 1 for the drive, and a little 
glue logic in between.  When a drive isn't plugged into them, they look 
like a disk with 0 capacity.  When a drive is plugged into them, they 
look like a disk with the capacity of the drive that was plugged in.  
The adapters are not very complex, hence their low prices.

The machine's IDE subsystem is not aware that disks are getting swapped 
in and out because IDE was not built to handle hotswapping--that's why 
you have to do things with atacontrol or hdparm -RU.

-- 
   You have me mixed up with more creative ways of being stupid.
   --MegaHAL, trained on random gibberish
There is no Darkness in Eternity/But only Light too dim for us to see