Re: RAID superblock confusion

[Mike Fedyk]

On Wed, Apr 10, 2002 at 04:49:06PM -0600, Richard Gooch wrote:
> Mike Fedyk writes:
> > On Wed, Apr 10, 2002 at 03:39:09PM -0600, Richard Gooch wrote:
> > > Mike Fedyk writes:
> > > > On Wed, Apr 10, 2002 at 02:37:48PM -0600, Richard Gooch wrote:
> > > > > 
> > > > > The device is set up (i.e. SCSI host driver is loaded) long before I
> > > > > do raidstart /dev/md/0
> > > > 
> > > > But kernel auto-detection doesn't depend on the raidstart command.  If
> > > > things are setup correctly, you can remove that from your init scripts.
> > > 
> > > I'm not (explicitely) using auto-detection. When I insmod the raid0
> > > module, there are no messages about finding devices. All I get is:
> > > md: raid0 personality registered as nr 2
> > > 
> > > Only when I run raidstart do I get kernel messages about the devices.
> > > 
> > > In any case, I should be able to move my devices around (especially
> > > if /etc/raidtab is still correct), whether or not autostart is
> > > running. The behaviour I'm observing is a bug (I assume it's not a
> > > mis-feature, since the raidstart man page tells me that moving devices
> > > around should be safe).
> > 
> > Ehh, I ran into this a while ago.  When you compile raid as modules
> > it doesn't use the raid superblocks for anything except for
> > verification.  I took a quick glance at the source and the
> > auto-detect code is ifdefed out if you compiled as a module.
> 
> Exactly where is this? A scan with find and grep don't reveal this.
>

drivers/md/md.c

in the ifndef MODULE sectioin.

> > Ever since I have had raid compiled into my kernels.
> 
> This is my relevant .config:
> CONFIG_MD=y
> CONFIG_BLK_DEV_MD=y
> CONFIG_MD_LINEAR=m
> CONFIG_MD_RAID0=m
> CONFIG_MD_RAID1=m
> CONFIG_MD_RAID5=m
> CONFIG_MD_MULTIPATH=m
> 

Set this to =y and you're set.

I'd like to see this working from modules though.

Mike