Re: [PATCH] 2.4.19 scsi_rescan patch (2nd pass)

[Doug Ledford <dledford@redhat.com>]

On Wed, Oct 02, 2002 at 09:40:06AM -0700, Cress, Andrew R wrote:
> James,
> 
> A user-space hotplug event can't be guaranteed to have enough information in
> all cases.
> Possible cases:
>   1) Administrator "knows" and manually issues a hot-plug command. 
>   2) A daemon detects a SAF-TE or SES event by slot number.  
>      Not sure if we can really determine what we need from just a slot
> number?
>   3) Other external disk enclosure (JBOD) that doesn't expose a 
>      SAF-TE or SES interface.
>      This case is out in the cold without the kernel-level rescan.
> 
> I'm disregarding case (1), since my target customer environment won't
> tolerate the manual step.

You can forget 3 as well.  It's simply not reasonable to tie up a busy bus 
with very long selection timeouts to "poll scan" a bus for new insertions.  
Not gonna happen.  If the JBOD doesn't expose a reasonable interface, then 
hot plug with it isn't supported in linux.  If it exposes something other 
than SAF-TE or SES then the protocol it does support needs to be added to 
the daemon in #2 in order for it to be supported.


-- 
  Doug Ledford <dledford@redhat.com>     919-754-3700 x44233
         Red Hat, Inc. 
         1801 Varsity Dr.
         Raleigh, NC 27606