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[dm-devel] Re: [PATCH] hostraid dmraid plugin should check for hostraid controller



On Tue, 2006-03-07 at 15:00 -0800, Darrick J. Wong wrote:
> Hi all (and Heinz in particular),
> 
> The attached patch against dmraid v1.0.0rc10 removes an unneeded
> comment, supplements an existing one, and most importantly, and causes
> is_asr to reject a disk if it can prove that the PCI controller attached
> to the disk is not a categorized as a RAID controller (this
> characteristic of the PCI class code is true for all the hostraid
> adapters in my lab).

It's not true for all of the ones on my desk... some show themselves as
IDE, some as SCSI, and some as SATA.

> This part of the patch helps us to avoid the situation where you can
> take a disk out of a HostRAID array, plug it in to a different system,
> and have dmraid -ay go all haywire when it can't find the rest of the
> disks.  It is my intent, however, that if is_asr will not reject a disk
> if it can't make this positive identification; this patch therefore
> should not affect Heinz's dm-based fakefakeraid testing rig. :)

It also screws up the recovery case -- moving a set of disks from one
machine to another just to read them.

We need to be treating "discovery of new, unexpected raidsets"
differently from "discovery and assembly of raidsets we know about", but
really that's at a higher level than what the "dmraid" utility is doing.
It just scans; it doesn't care why.  For this sort of elimination, you
care about why.

-- 
  Peter


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