drbdsetup: 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 Debian possible default full paths are:

/sbin/drbdsetup - from package: drbd-utils

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

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