On Aug 1, 2006, Bill Davidsen <davidsen@xxxxxxx> wrote: > I rarely think you are totally wrong about anything RAID, but I do > believe you have missed the point of autodetect. It is intended to > work as it does now, building the array without depending on some user > level functionality. Well, it clearly depends on at least some user level functionality (the ioctl that triggers autodetect). Going from that to a full-fledged mdadm doesn't sound like such a big deal to me. > I don't personally see the value of autodetect for putting together > the huge number of drives people configure. I see this as a way to > improve boot reliability, if someone needs 64 drives for root and > boot, they need to read a few essays on filesystem > configuration. However, I'm aware that there are some really bizarre > special cases out there. There's LVM. If you have to keep root out of the VG just because people say so, you lose lots of benefits from LVM, such as being able to grow root with the system running, take snapshots of root, etc. Sure enough the LVM subsystem could make things better for one to not need all of the PVs in the root-containing VG in order to be able to mount root read-write, or at all, but if you think about it, if initrd is set up such that you only bring up the devices that hold the actual root device within the VG and then you change that, say by taking a snapshot of root, moving it around, growing it, etc, you'd be better off if you could still boot. So you do want all of the VG members to be around, just in case. This is trivially-accomplished for regular disks whose drivers are loaded by initrd, but for raid devices, you need to tentatively bring up every raid member you can, just in case some piece of root is there, otherwise you may end up unable to boot. Yes, this is an argument against root on LVM, but there are arguments *for* root on LVM as well, and there's no reason to not support both behaviors equally well and let people figure out what works best for them. -- Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/ Secretary for FSF Latin America http://www.fsfla.org/ Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org} Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org} - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
