Ubuntu 20.04 multipath configuration

I just installed a new Ubuntu 20.04 server as a virtual machine on an esx-Server. When I look into systemlog I see lots of multipath entries.

multipathd[651]: sda: add missing path
multipathd[651]: sda: failed to get udev uid: Invalid argument
multipathd[651]: sda: failed to get sysfs uid: Invalid argument
multipathd[651]: sda: failed to get sgio uid: No such file or directory
multipathd[651]: sda: add missing path
multipathd[651]: sda: failed to get udev uid: Invalid argument
multipathd[651]: sda: failed to get sysfs uid: Invalid argument
multipathd[651]: sda: failed to get sgio uid: No such file or directory

I think multipath is just not configured and my question is if I can disable multipath. Since I checked this on several Ubuntu 20.04 servers multipath is enabled by default.

Does it make sense to activate multipath?

Solution 1:

There is a SUSE linux KB on the topic - https://www.suse.com/support/kb/doc/?id=000016951. The problem is that VMWare by default doesn't provide information needed by udev to generate /dev/disk/by-id entries. Apart from ESX, VMWare Workstation (my case) is also affected. The resolution is to put

disk.EnableUUID = "TRUE"

to the virtual machine definition, i.e. into the *.vmx file or via Edit Settings -> Options tab -> General -> Configuration Parameters in ESX UI.

After rebooting VM with this parameter set, the disk are visible in /dev/disk/by-id and multipathd doesn't complain anymore.

Solution 2:

If you dont have access to your host ESX you can add the following lines to your /etc/multipath.conf file which also blacklists common other devices like CDRom drives etc.

defaults {
    user_friendly_names yes
}
blacklist {
    devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st|sda)[0-9]*"
}

Solution 3:

Through this, I have resolved my issue:

1. Run vi /etc/multipath.conf and add this to the file:

   defaults {
       user_friendly_names yes
   }
   
   blacklist {
       device {
           vendor "VMware"
           product "Virtual disk"
       }
   }
   

2. Restart the multipath-tools service:

   /etc/init.d/multipath-tools restart