Hey,

from https://ovirt.org/blog/2017/12/lvm-configuration-the-easy-way.html

"""

Why is a solution required? Because scanning and activating other logical volumes may cause data corruption, slow boot, and other issues.

The solution is configuring an LVM filter on each host, which allows LVM on a host to scan only the logical volumes required directly by the host. To achieve this, we have introduced a vdsm-tool command, config-lvm-filter, that will configure the host for you.

The new command, vdsm-tool config-lvm-filter analyzes the current LVM configuration to decide whether a filter should be configured. Then, if the LVM filter has yet to be configured, the command generates an LVM filter option for this host, and adds the option to the LVM configuration.

"""

Is that what you're looking for?

We should improve the docs here. Would you mind filing a documentation bug on https://github.com/oVirt/ovirt-site/issues/new ?

Best wishes,

Greg

On Thu, Jan 3, 2019 at 12:08 PM <tehnic@take3.ro> wrote:

Hello all,

i have a question regarding this note in ovirt storage documentation:

**Important:** If you are using block storage and you intend to deploy virtual machines on raw devices or direct LUNs and to manage them with the Logical Volume Manager, you must create a filter to hide the guest logical volumes. This will prevent guest logical volumes from being activated when the host is booted, a situation that could lead to stale logical volumes and cause data corruption.

What does "you must create a filter to hide the guest logical volumes" exactly mean?
I assume i have to set some filter in lvm.conf on all ovirt hosts, but im not sure about what to filter?

What i already saw is that after creating the ISCSI domain and cloning/moving/creating virtual machines on it there are new PVs and LVs visible on the ovirt hosts having an object UUID in the name (output from "pvs" and "lvs" commands).
Is this expected behavior or do i have to filter exactly this ones by allowing only local disks to be scanned for PVs/LVs?
Or do i have to setup filter to allow only local disks + ISCSI disks (in my case /dev/sd?) to be scanned for PVs/LVs?

I noticed too that after detaching and removing the ISCSI domain i still have UUID PVs. They all show up with "input/output error" in the output of "pvs" and stay there until i reboot the ovirt hosts.

On my ISCSI target system i already set the correct lvm filters so that "targetcli" is happy after reboot.

Thank you!

Happy new year,
Robert
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