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lvm.conf on storage/compute nodes

asked 2017-07-20 14:59:51 -0500

isabyr gravatar image

I can't understand how to properly configure filters in lvm.conf on cinder nodes. I'm already using lvm for the host os(vg_main contains / and /var volumes) and created vg_cinder volume group for further cinder usage. So how should I:

  1. Configure filters in lvm.conf on host OS?
  2. Configure filters in lvm.conf on guest OS?

I'm installing using this https://docs.openstack.org/ocata/install-guide-ubuntu/cinder-storage-install.html (guide)

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answered 2017-07-23 00:42:43 -0500

updated 2017-07-23 00:43:43 -0500

The guide tells you what to do on the storage node. You just accept all those disks with physical volumes that belong to the host, and ignore those that don't belong to the host. The guide uses this example:

devices {
...
filter = [ "a/sdb/", "r/.*/"]

The "a" means "accept". The snippet above accepts /dev/sdb, which assumes that /dev/sdb or a partition like /dev/sdb1 is a physical volume. The "r" is needed to reject all other disks. As a result, LVM only considers /dev/sdb. In case the host uses LVM on /dev/sda as well, you also have to accept it.

Configuring lvm.conf in this way is necessary because the host "sees" LVM structures on guests' disks. You want the host's LVM to ignore those. The guests only see their own disks, so that you can leave lvm.conf alone. Especially in a proof-of-concept or learning context.

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So if I understand correctly, hosts should not scan devices created by/for guests, so we just hardcode partitions used by host(including the partition for the cinder-volumes)?

isabyr gravatar imageisabyr ( 2017-07-23 04:01:26 -0500 )edit

I think that's a correct description.

Bernd Bausch gravatar imageBernd Bausch ( 2017-07-23 21:38:48 -0500 )edit

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Asked: 2017-07-20 14:59:51 -0500

Seen: 115 times

Last updated: Jul 23 '17