fence_kdump: 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_kdump - from package: fence-agents

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

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