Luca Berra wrote: >> Why is this necessarily so? RAID autodetect seems >> to avoid a lot of configuration hassles especially >> when your root partition is involved. Any horror >> stories to tell? > yes, read the linux-raid mailing list for those, i > am tired of beating the same dead horse. Well, I'm new to Linux raid, perhaps you can point me to some of the messages referring to such incidents. I don't seem to see a lot of them on the raid list and RAID autodetect seems to work well for me (under the 2.4 kernel). I'll start believing this when I hear that they've deprecated the RAID autodetect partition type. What I DO read about a lot are people recommending against using lvm on their root partition. >> People have recommended against using an LVM >> volume for your root partition citing the hassle of >> a rescue disk as being the main reason. > this is just ridicolous fud. Ehrm... just for the record... that recommendation came from Heinz, the LVM guy, himself: "having root on a logical volume needs an initrd which causes hassle in case soemthing goes wrong at boot and you don't have an emergency boot media with all necessary sw (i.e. LVM etc.) on it." http://www.redhat.com/archives/linux-lvm/2003-February/msg00030.html Like you, though, I disagree with it - as I've explained earlier, if you can't use LVM on your root partition, what's the point? > in what cases you would need a rescue disk? > are those really different from the cases you'd need a > rescue disk for a normal partition-table based system. > > besides, every live distro on earth now supports lvm > and can be used as a recovery tool. Although when you say "every live distro on earth", which parallel earth would that be? I invite you to download Slax 4.2.0 (the most current downloadable version of this popular live CD at the time of your reply), burn it to CD, and let me know if you are able to find vgchange and vgscan on it. > i have been using my root partition as a logical volume > for several years now. Several years, eh? Just curious, which distro are you using? >> Unless lvm detect/enable functionality were built into >> the kernel though, you will always have to live with a >> physical partition holding /boot - the case today >> with LVM and RAID0, but not RAID1 (from which it is >> possible to boot directly off of). > i don't have a separate partition for /boot on my lvm systems. > the only reason i needed a separate boot partition was when i > had a system using raid5, so i had to have a separate raid1 > partition for booting. This sure is news to me. Which kernel version/boot loader are you using? What output do you get when you run 'mount' or 'cat /proc/mounts' ? > Reading your arguments it appeare you are mis-informed and > make a lot of confusion between a boot loader (which is the > only limitation we have in loading a kernel/initrd/initramfs) > and what the kernel can do. With LILO and the lvm in the 2.4 kernel, I am **pretty sure** you CAN'T boot directly into a lvm root partition. The kernel (which is in /boot) *has* to reside in a partition readable by LILO (i.e. ext2, reiser, RAID 1 md or ataraid but NOT lvm) and be loaded in from there. Furthermore, you *have* to make an initrd from which you will have to run 'vgscan; vgchange -an' from, otherwise the lvm partition will be invisible to the kernel. And this is exactly where the hassle lies and where the rationale comes from for wanting vgscan/vgchange _functionality_ (not necessarily the programs themselves) in the kernel like the case with md today. To reiterate, if lvm incurs as little overhead as it is claimed to, it makes sense for people to stop using physical partitions and start using lvm all the time. That would certainly make Linux more _friendly_ than XP in this area. -- reply-to: a n d y @ n e o t i t a n s . c o m _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
