Re: Patch to add RAID autostart to IBM partitions

[Pete Zaitcev <zaitcev@redhat.com>]

On Sat, 16 Oct 2004 12:09:39 +0100
Christoph Hellwig <hch@infradead.org> wrote:

> We had this for a few partition types (and full block devices) already
> and it's been vetoed.  Use mdadm from initrd/initramfs instead.

It is doable in theory, but in practice mdadm is too retarded (I'm taliking
about mdadm 1.6.0 here). Its man page says:

    mdadm can perform (almost) all of its functions  without  having  a
    configuration  file  and  does  not use one by default.

I guess "almost" is the key. Firstly, it collapses with any attempt to run
"mdadm -A -s" or any variation of such, because it's full of places like
this.

	mddev_ident_t array_ident = conf_get_ident(configfile, dv->devname);
	mdfd = open_mddev(dv->devname, array_ident->autof);

Obviously, array_ident is NULL if a config file is not present. It is
possible to fool the stupid thing by giving it a dummy config file,
like this one:

DEVICE partitions
ARRAY /dev/md0

It still won't scan, aborting with this:
mdadm: /dev/dasda has no superblock - assembly aborted

The ChangeLog looks as if someone tried to make it work, but I observe
it didn't go very far.

-- Pete