disk_stats_test: 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:

/usr/lib/plainbox-providers-1/checkbox/bin/disk_stats_test - from package: plainbox-provider-checkbox

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

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