dmraid: How best to detect if dmraid devices are present

[Phillip Susi]

Frans Pop wrote:
> Hello,
> 
> I've been working on implementing dmraid support in the Debian Installer, 
> and have been using 'dmraid -s -c' to detect if any dmraid sets are 
> present.
> 
> Problem with that is that 'dmraid -s -c' will in at least two situations 
> exit zero and display what for my purposes is effectively an error 
> message on stdout:
> - no block devices found
> - No RAID disks

I was thinking you would want to specifically direct dmraid to scan for 
the metadata on each individual disk as they are enumerated rather than 
just waiting until all disks have been enumerated ( how do you even know 
when this is? ) and letting dmraid look at all the disks it can find.