Neil,

Reading your blog post,

  "Auto-assembly mode for mdadm"
   http://neil.brown.name/blog/20060521092609

Section "Bootstrapping" says

-------------
On problem with introducing this functionality is that people have
pre-existing array that aren't tagged with the host name. To help we
this we will have a new 'update' option of --assemble:
--update=homehost which will update the host information in the
superblock prior to assembly. This is usable fairly easily for
everything except an array holding a root filesystem. In order to
avoid needing to boot from different media, there will be an option
that can safely be used from an initramfs which will do the right
thing.

This will probably be called --auto-update-home-host.

This option is only meaningful when doing a hostname based auto
assembly. If the autoassembly process finds anything to assemble, the
option is ignored. However if nothing is found with the right host
name, then a second pass is made. On this pass, any md array that is
found is updated to belong to the current host, and is automatically
assembled.

Thus it should be safe to always run mdadm with
--auto-update-home-host in initramfs. It will only do its magic once,
and after that the arrays should always assemble properly.
-------------

That describes the situation I have -- an array holding the root file
system, that's not tagged with the hostname.

Can you please explain HOW one runs "with --auto-update-home-host in
initramfs" "to avoid needing to boot from different media"?  My
existing arrays are tagged with the wrong name, and I'm simply trying
to correct it.

Thanks,

BenDJ