Bug#337704: evms root on lvm/md [was Re: bug 336617]
hurrah for opening an separate bug.
Sesse is using plain EVMS root, you seem to use an heavier mix.
Yes, as I mentioned, I use just about every little bit of EVMS on the
way up. My root is a LVM2 volume inside a LVM2 container inside a RAID5
md array, all controlled by evms.
your patch also seems not to be clean enough yet,
because he removes prerequisites only to add them later on.
No, actually Sesse and I discussed my patches before I submitted them,
because I was going to try to use the prereq mechanism, but after
discussion, we both decided that keeping evms independent from lvm/md is
a much cleaner solution.
Background: EVMS supplies all the user mode tools to manage
EVMS/LVM/LVM2/MD even though it requires the LVM and MD kernel
subsystems to actually provide volume management and raid.
In fact, installation of the raid-tools and lvm2 tools is mildly
discouraged in the evms community because we don't want MD and LVM to
try to bring stuff up independently. The initramfs prereq mechanism
expects LVM and MD usermode tools to exist, and then tries to activate
LVM and MD components using those tools. If the user mode tools are not
installed, nothing works. If they are installed, but we're running
evms, evms_activate fails. Ugly problem.
can you please add more info about your setup to your bug report:
/etc/fstab, pvscan and /proc/mdstat
why is /etc/evms.conf needed?
Because evms_activate needs it if settings do not follow the default
exactly. We use it in initrd for this very reason. For example, you
may not wish to activate certain partitions under evms (perhaps due to
the bd-claim problem in 2.6 kernels) or you need to tell evms_activate
that you've got LVM2 volumes on top of raw md partitions and to ignore
the PV sizes.
you add lots of evms libs:
+for x in bbr bbr_seg bsd disk dos drivelink gpt lvm2 mac md multipath; do
Yes, I was careful to add only the ones absolutely necessary for
bringing up a bare root on one of the supported debian architectures:
dos,gpt,mac,bsd = segment modules (e.g. the DOS partition table)
bbr,bbr_seg = bad block replacement segment module
drivelink,lvm2,md,multipath = evms plugins to support multi-device
partitions
Unfortunately, all of this crap is necessary to boot if you don't know
where your root is. Yes, it could be trimmed down with a huge effort,
but then you could be seriously screwed if you moved your root inside of
evms (e.g. from a raid0 to a raid5 region) but forgot to rebuild your
initramfs. When Sesse and I discussed optimizing it, he encouraged me
not to.
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