Hi,

On 26 Jun 2002 at 12:41, Jason R Thorpe wrote:
> The hot-swap is handled by the driver, as I understand it.  When you
> swap a drive, the OS has to be told.  The OS then stops using the
> drive and considers it "gone", you pull the old drive out using the
> sled (which only provides a convenient mechanism to do this, nothing
> else special),

A distributor of promise asked me to help one of their 
customers, so I tested a Fasttrack 100TX2 under Linux with 
both the Promise binary only driver and the Linux kernel 
driver (port of FreeBSDs driver). I tested only a simple 
mirror with one drive on each channel.

When I disconnect the power or data cable of one of the 
drives, the system freezes for at least minutes (powercycled 
the machine after about 15 minutes - no telnet, ping etc.).

When using the hotswap drive chassis of promise or others 
(kingston or Kensington makes such too), the driver will send 
his error message to syslog and continues the operation. A 
standard "removable hdd rack" shows the same problems you get 
by just removing the cables.

Actually I could not get any useful technical information from 
promise (and I work for their distributor in that case), but 
IIRC the hotswap chassis will "emulate" a disk, that is not 
ready to receive data. It is very unlikely that there is some 
special signalling, as the promise controllers work with other 
(as said Kingston/Kensington) chassis.

From my POV the problem is, that even if one does not need 
hotswap functionallity, there will be no protection if a drive 
fails if it is connected to the controller without the hotswap 
chassis logic.

HTH

mike