On Saturday, March 26, 2011 02:13:49 pm John R Pierce wrote:
> On 03/26/11 9:51 AM, Ray Van Dolson wrote:
> > The HP MicroServer does have hot-swappable trays...  Great little box.
> the specs say non-hot-plug repeatedly.
[snip]
> and refers to them as 'internal SATA drives'  ?

While in most cases internal drives aren't considered 'hot-swap' since opening 
the case isn't typically a thing you'd think of when considering something 
'hot-swap,' according to the libATA wiki at 
https://ata.wiki.kernel.org/index.php/SATA_hardware_features says that the AMD 
SB820M is AHCI, and supports hot-swap.  

In most cases, true hot-swap trays and cages for SATA (like the ones for 
SuperMicro cases, to use one example) have no special 'interposer' logic like 
some hot-swap IDE and SCSI cages do, that does a staged disconnect when you 
turn the drive off with the key on the tray; it's a built-in feature of the 
drive (staggered contacts on the connector pair) and the controller for SATA, 
and especially AHCI.  The 2U 6 tray SATA cage for the SuperMicro box I have has 
direct pass-through for all 6 of the SATA positions.

80-pin SCA SCSI cages (again, like the 6 tray Supermicro ones) can use the SCA 
connector's pin stagger to good advantage, and most of the time don't need 
interposer chips.

So you're not likely to damage anything by hot-swapping an internal SATA drive 
(as long as you issue the ioctls necessary, and things aren't mounted, etc), as 
long as you don't drop a screw on the running motherboard.....which is a real 
risk, by the way (yeah, I've done that, too).  So it's not a good idea, but it 
could be done in an emergency, I guess (I say I guess, but in fact I have done 
this more than once, with a tower case where the drives were in easily 
removeable cages that didn't have screws to drop, and were well away from the 
motherboard or any other exposed energized components).

I've even done it with a laptop running on a liveCD.....
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