[linux-lvm] Question about filter behavior on pvcreate /dev/md0

[Zdenek Kabelac]

Dne 13. 06. 19 v 9:41 Heming Zhao napsal(a):
> Hello List,
> 
> I created a md device, and used pvcreate to format it.
> But the pvcreate was failed with filter rules.
> the filter in /etc/lvm/lvm.conf:
> ```
> filter = [ "r|/dev/.*/by-path/.*|", "r|/dev/.*/by-id/.*|",
> "r|/dev/fd.*|", "r|/dev/cdrom|" ]
> ```


Hi

This filter mostly eliminates ANY block device you have in the system.
The logic of filtering can be seen as puzzling, but please try to read 
carefully comments in lvm.conf about filtering. It's explained there in the 
great detail.

As soon as the 'accept' rule is seen - the device gets accepted.
Otherwise if you remove device path - all it's associated clones will be also 
removed.

So when you block device generates one of /dev/*/by-path access paths (and I'd 
assume /dev/md0 should be) - it gets removed.

As 'quick fix' you can add 'a' rule for /dev/md.*...

Regards

Zdenek