[LUAU] SATA hot swap - off topic

[MonMotha]

Vince Hoang wrote:

> 
>>MonMotha wrote:
>>
>>>This is mostly useful on RAID arrays though.  See the raidhotadd and
>>>raidhotremove (or is it raidhotdel?) commands.
> 
> 
> I believe this only tickles the md driver and not the bus.
> 

Indeed it does.  I was mostly giving an example of a practical use for 
all this hotswap stuff.

hdparm -x will tristate the bus, allowing safe hotswap if the controller 
and drive support it (and I'm told all SATA devices are supposed to). 
In general, Linux doesn't really care much about hardware suddenly 
disappearing (though it will usually whine a bit), though it might not 
always see it when it reappears.

hdparm -R to register the IDE device and hdparm -U to unregister it 
might find some use if this "problem" occurs.  Make darn sure you've got 
it unmounted (and, if it's in a RAID array, it's a good idea to 
hotremove it, though being RAID, this is not strictly required, first) 
before you do this, or you WILL end up with a dirty filesystem, and the 
fs layer of the kernel might not immediatley notice and may even try to 
continue writing to the (now nonexistant) device.  That's a bad thing :)

I know hdparm -R, -U, and -x can be used to swap "bay" devices on IBM 
Thinkpads.

--MonMotha