(Semi)hot swap IDE

Toomas Aas toomas.aas at raad.tartu.ee
Sat Nov 22 12:32:01 PST 2003


I'm looking for a cheap solution to back up a FreeBSD 4.8 machine. 
Cheap meaning that tape drives are out of question. Even external 
FireWire drives are deemed a bit too expensive by the folks for whom 
I'm doing this research.

This leaves one option I can think of - standard IDE drive in one of 
those removable HDD trays. We'd probably use two drives, one being 
active in the machine and the other being kept somewhere out of the 
house for safety. The machine has an integrated Promise TX2 controller 
and two 80 GB drives are currently configured as RAID1 attached to this 
controller. There are two additional (non-RAID) IDE channels on the 
motherboard, one of them has CD-ROM attached to it and the other is 
free - I could attach the backup HD to that.

I've done some web searching and I'm getting controversial results. 
Most of the info I find seems to indicate that IDE devices cannot be 
hot-swapped. At the same time some vendors are trying to sell stuff on 
their web pages which they advertise as "hot swap IDE drive bays". I 
remain skeptical.

If the majority is right and IDE drives cannot be hot swapped, this 
would indicate that we would need to power down the machine every time 
we want to change the backup HDs. This would be less than perfect, but 
since we are cheap we could live with it. 

OTOH I read 'man atacontrol' and saw that there are commands like 
'atacontrol detach' and 'atacontrol attach' which seem to be meant for 
detaching/attaching IDE devices while the machine is running. Does this 
mean that I could actually run 'atacontrol detach <channel>', swap the 
drive and then run 'atacontrol attach <channel>' and be able to use the 
second HD after that? Is anyone doing something like that?
Toomas Aas | toomas.aas at raad.tartu.ee | http://www.raad.tartu.ee/~toomas/
* I don't know whether to kill myself or go bowling

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