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Thomas Aichinger
Asked: 2020-05-24 00:31:13 +0800 CST

Ubuntu 20.04 multipath configuration

  • 772

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?

server 20.04 multipath

7 Answers

  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.

    • 38

  2. 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
    • 33

  3. 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]*"
}
    • 26

  4. Adding the below into the guest vm parameters worked for me. The syslog is no longer complaining and the server appears to be staying up.

    disk.EnableUUID = "TRUE"

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

    Ubuntu 20.04 running apache and Wordpress php-7.4-fpm

    • 2

  5. I'd use a:

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

    for sda, sdb, etc.

    • 1

  6. Here is another way to set it.

    Use govc

    Setup GOVC_URL first like

    export GOVC_URL='https://username:[email protected]/sdk'

    and set UUID like

    govc vm.change -e="disk.EnableUUID=TRUE" -vm='MY_VM_NAME'

    One more thing, you have to poweroff and poweron to take effect this change

    govc vm.power -off -force VM1
govc vm.power -on -force VM1
    • 0

  7. If you don't need multipath, turn it off:

    systemctl disable multipathd
systemctl stop multipathd
    • 0