[linux-lvm] Multipath / LVM2

malahal at us.ibm.com malahal at us.ibm.com
Tue Mar 16 18:08:20 UTC 2010

blub at trans.am [blub at trans.am] wrote:
> hello
> I have troubles to get multipathing working on gentoo. I have an identical
> setup working on a debian box.
> The problem is that LVM does not detect labels on the multipath device
> node; instead it does try to use a physical path (eg /dev/sda1)

One easy way to avoid using the paths rather than actual multipath
devices is to use filtering in /etc/lvm/lvm.conf. Like below:

# Use only names from /dev/mapper directory
filter = [ "a|/dev/mapper/.*|", "r/.*/" ]

> the device nodes /dev/dm-X are not automaticaly created like they get on
> debian, I did run dmsetup mknodes which did not create /dev/dm-X nodes, so
> i created /dev/dm-0 with the minor/major of the corresponding /dev/mapper/
> node. I don't know if this is a problem.

This is odd, maybe something to do with udev rules? Anyway, you don't
need /dev/dm-X nodes if you use LVM filtering.

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