I forgot to mention that I move the md0 entry back into place after I run vgscan. It's worked quite well and across numerous reboots. It is VERY ugly, but it "Works For Me(TM)" :) On Wed, 2003-04-30 at 15:30, Ewen McNeill wrote: > In message <1051724087.19901.287.camel@cinshrlnxws01.shermfin.com>, Andrew Reche > nberg writes: > >>[LVM 1.0.x; vgscan finds parts of RAID arrays and uses those instead] > >vgscan has similar problems with MD devices in a software RAID10 (but > >not RAID1) configuration. [...] > > Interesting. I've been told, and found in the source, that there were > some hacks in LVM to make LVM and md work in some common situations > (basically there's a loop after the first device scan which tries to > eliminate some of the duplicates; and there's a /* FIXME */ comment > immediately before that loop). It seems that you've found one of > the situations where these hacks are too limited. > > >I was trying to hack vgscan to get my setup working but I needed the box > >working ASAP so time dictated that I use the KludgeMethod(tm). Someone > >on the list recommended that I move /dev/md0 before I run my vgscan. > >[....] > > That is really quite ugly :-) I suspect something like that might work > for the ataraid case too, right up to the point that someone runs vgscan > for some reason without going through the "hide things from vgscan so it > doesn't get it wrong" ritual -- at which point (with a little prompting) > it silently swaps over to using part of the RAID array, and the RAID > array gets out of sync, and then on next reboot it swaps back to using > the RAID array, and the partitions are corrupt. > > I'm afraid that's a little too much potential excitement for my liking! > > I've been told that LVM 2 has some support where you can say what > devices to scan (and what devices not to scan). I've not looked at LVM > 2 yet, so I don't know how fine grained it is, but it might suit your > situation. > > However after all this investigation I can't help thinking that the LVM > vgscan approach is broken by design, particularly to be run automatically > on startup. The idea that one can somehow look through all the connected > devices and guess which one to use, and then automatically use those > guesses on the assumption they'll always be right, just seems to be asking > for trouble. Static configuration files, and having these things under > manual control, seems a far more reliable way to approach the situation. > > For now this ataraid system will be built without LVM, as it seems the > only way to be sure that the RAID array will actually always be used. > > Thanks for your comments, > > Ewen > > _______________________________________________ > linux-lvm mailing list > linux-lvm@sistina.com > http://lists.sistina.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ -- Andrew Rechenberg <arechenberg@shermfin.com> Infrastrucutre Team, Sherman Financial Group _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
