mkaf: 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/libexec/pcp/bin/mkaf - from package: pcp

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

On Debian possible default full paths are:

/usr/lib/pcp/bin/mkaf - from package: pcp

You may install the required package with command apt-get install {package}

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