rbd: 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/bin/rbd - from package: ceph-common

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

On Debian possible default full paths are:

/usr/bin/rbd - from package: ceph-common

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

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