[CentOS] My new server

Lamar Owen lowen at pari.edu
Sat Mar 26 21:44:59 UTC 2011

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.
> 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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