RHV host boot into emergency mode after upgrade

Environment

• Red Hat Virtualization (RHV) 4.2, 4.3

Issue

• After upgrading the RHV host, it is booting into emergency mode with the error about the unavailability of logical volumes.
• The host is having LVM filter configured.
• I have an lvm filter that allows only the boot disk to be seen on the host, and nothing else, ie: (lvm.conf):

filter = [ "a|^/dev/sda2$|", "r|.*|" ]

• When upgrading to the latest RHV-H, host fails during reboot. (stops at emergency shell)
• /boot is now a /dev/mapper/xyz device

Resolution

• To allow the host to boot again, in emergency shell, replace lvm filter with an 'open' filter, ie:

filter = [ "a|.*|" ]

Then reboot. Once the host has come up, a new filter can be calculated if needed:

vdsm-tool config-lvm-filter

• If the boot device is a local disk, please follow the Documentation - Ignoring Local Disks when Generating Multipath Devices on how to ignore the local disk using the WWID of the device. For example:

blacklist {
      wwid SIBM-ESXSST336732LC____F3ET0EP0Q000072428BX1
}

• If it's a SAN LUN, then change the LVM filter to include the multipath device instead of sd device.

Root Cause

The LVM filter is configured with /dev/sda. However multipath added the same device into the multipath table. Because of this, LVM will not be able to acquire the device and it will fail since a multipath device is created on top of this device.

This content is not included.RHBZ#1656259

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