fence_mpath: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/sbin/fence_mpath - from package: fence-agents

You may install the required package with command yum install {package}

Error in other languages:
fence_mpath: bevel nie gevind nie
fence_mpath: comandă negăsită
fence_mpath: comando não encontrado
fence_mpath: commande introuvable
fence_mpath: command not found
fence_mpath: käsku ei ole
fence_mpath: không tìm thấy lệnh
fence_mpath: komanda nerasta
fence_mpath: Kommando nicht gefunden.
fence_mpath: kommandot finns inte
fence_mpath: komut yok
fence_mpath: nie znaleziono polecenia
fence_mpath: níor aimsíodh an t-ordú
fence_mpath: no se encontró la orden
fence_mpath: no s'ha trobat l'ordre
fence_mpath: opdracht niet gevonden
fence_mpath: parancs nem található
fence_mpath: perintah tidak ditemukan
fence_mpath: príkaz nenájdený
fence_mpath: příkaz nenalezen
fence_mpath: команда не найдена
fence_mpath: командата не е открита
fence_mpath: 命令找不到
fence_mpath: コマンドが見つかりません