Package: mdadm Version: 2.5.2-9 Severity: wishlist Documenting this possible future change, which came up during the discussion about mdassemble, which is lighter than mdadm and could thus be used during boot, or in the udeb.
----- Forwarded message from Neil Brown <[EMAIL PROTECTED]> ----- > I had another question about mdassemble... it requires mdadm.conf, > right? I currently just create that file during boot because of > http://bugs.debian.org/284022 -- is there a better way you suggest? > I could just copy the file into the initramfs from the host, but > then maybe there have been changes made to the RAID configuration > without /etc/mdadm/mdadm.conf being updated, and noone noticed > because everything continued to work because of the initramfs... Yes, mdassemble and mdadm --assemble require mdadm.conf. It is needed to identify the arrays to be assembled. This may seem to make it difficult to just "Assemble all arrays that you can find", but that is very deliberate. I think doing that is the wrong thing to do. It can get confused when moving drives from one machine to another. To address this issue I wrote the 'homehost' stuff. Check the man page for details. The idea is that all arrays belonging to a particular host are tagged with the host's name, and then they can be found and assembled reliably. So: in mdadm.conf put CREATE homehost=<system> (literally) and every array created with be tagged with the hostname from gethostname(2). In initrd, put mdadm --assemble --scan --homehost='<system>' --auto=yes --auto-update-homehost and make sure the hostname is set at this point (that might be the tricky bit). Then mdadm will scan all devices for md array components that are tagged for this host and will assemble them all (without a config file). If it doesn't find any arrays, then the --auto-update-homehost thing comes into play. It will rescan all devices looking for any md - nomatter what host it is tagged for - and will rewrite the superblocks to be for 'this' host and will assemble them. On subsequent boots it will find some arrays tagged for this host and will assemble them and so will NOT do the auto-update thing. That only happens when NO md arrays for this host are found. The net result should be pretty much what everyone seems to want, but with enough caution to make me happy. The tricky bit, as I said, is making sure the host name is available to the initramfs. NeilBrown ----- End forwarded message ----- Making the hostname available to the initramfs is as easy as adding a line to the hook. -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:"; [EMAIL PROTECTED] spamtraps: [EMAIL PROTECTED] ... and don't get caught in the .NET!
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