btrfs-zero-log: 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:

/sbin/btrfs-zero-log - from package: btrfs-progs

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

On Debian possible default full paths are:

/sbin/btrfs-zero-log - from package: btrfs-tools

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

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