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Re: [dm-devel] oblem with lvm and multipath on fedora 13

Stamper, Brian P. (ARC-D)[Logyx LLC] [brian p stamper nasa gov] wrote:
>    Here’s what I’ve found:
>    If I vgchange the 2 affected VGs to inactive, multipath will pick up the
>    devices.  However, once I do that, I can’t seem to get the VGs reactivated
>    in such a way to make the volumes mountable.  I use vgchange –a y to make
>    the VG active, then do “vgscan —mknodes”.  That doesn’t seem to create the
>    devices in /dev, only in /dev/mapper, so I’ve tried issuing
>    /etc/init.d/udev-post reload, which does create the volumes in
>    /dev/<vg>/<lv>.  The issue is, it has no blkid.  And if I try to mount the
>    mapper device directly, mount doesn’t know what filesystem type it is.
>     I’m not an lvm pro, so it’s possible I’m missing a step or two, but in
>    the past when moving around snapshots of lvms, vgscan —mknodes has always
>    been sufficient.

The entries in /dev/mapper should work. If they don't work, other
entries don't work either. Based on the above information, can I assume
that you were able to mount such logical volumes without multipath (this
is very unusual, if true)? Inactivate affected VGs, run "multipath -F"
to delete multipath maps, and then activate your VGs. You should now be
where you were before and see if you can mount logical volumes that were
failing before (I doubt if they work though).

>    As for not having multipath in initrd, I have created an initrd image with
>    the following:
>    mkinitrd /boot/initramfs-with-multipath.img
>    --with=dm-multipath
>    I then created a grub entry for it, booted off it, and no change in
>    behavior.  Is that what you had in mind?

RedHat mkinitrd scripts go to great lengths to not include multipath in
initrd unless you are currently using your 'root' on multipath! Most
likely it didn't include multipath. You can expand the initrd (it is a
compressed cpio archive, 'zcat initrd.img | cpio -icd' should extract
all the files) and see if multipath is included (look for multipath
in the extracted files). I would suggest you work on your first problem
(not able to mount stuff).

Thanks, Malahal.

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