Re: HELP: Getting unexpected fakeraid behavior. Fix?

[Joseph Fannin <jfannin@gmail.com>]

On Sun, Jul 06, 2008 at 09:26:35PM -0400, Timothy Normand Miller wrote:
> I was poking around some more, and I found drivers/md/raid1.c.  This
> has sophisticated load balancing for reads.  Why isn't this code being
> used for dm_raid1?  I'm a bit confused as to why this redundant code
> should be there if dmraid and mdraid are functionally the same.

I don't think dmraid and mdraid *are* functionally the same.  dmraid
was written as more or less a compatibilty hack, so people using
fakeRAID with its Windows-only software drivers could still
dual-boot.  That could have changed somewhat while I wasn't looking,
but it doesn't sound like it has changed much.

mdraid is still the only "real" Linux softRAID
implementation... though LVM also does some very RAID-like things.

It would be good if dmraid was better optimized, or more complete --
possibly by reusing some of md -- but no one has done the work.

Anyway, the consensus for a long time seems to be that, unless you
need to dual-boot with a Windows system using fakeRAID drivers, you
should just put the drive controller in AHCI mode and use mdraid.

--
Joseph Fannin
jfannin@gmail.com