Re: "Enhanced" MD code avaible for review

[Jeff Garzik <jgarzik@pobox.com>]

Justin T. Gibbs wrote:
>>>None of the solutions being talked about perform "failing over" in
>>>userland.  The RAID transforms which perform this operation are kernel
>>>resident in DM, MD, and EMD.  Perhaps you are talking about spare
>>>activation and rebuild?
>>
>>This is precisely why I sent the second email, and made the qualification
>>I did :)
>>
>>For a "do it in userland" solution, an initrd or initramfs piece examines
>>the system configuration, and assembles physical disks into RAID arrays
>>based on the information it finds.  I was mainly implying that an initrd
>>solution would have to provide some primitive failover initially, before
>>the kernel is bootstrapped...  much like a bootloader that supports booting
>>off a RAID1 array would need to do.
> 
> 
> "Failover" (i.e. redirecting a read to a viable member) will not occur
> via userland at all.  The initrd solution just has to present all available
> members to the kernel interface performing the RAID transform.  There
> is no need for "special failover handling" during bootstrap in either
> case.

hmmm, yeah, agreed.

	Jeff