gfs2_fsck: 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/sbin/gfs2_fsck - from package: gfs2-utils

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

Error in other languages:
gfs2_fsck: bevel nie gevind nie
gfs2_fsck: comandă negăsită
gfs2_fsck: comando não encontrado
gfs2_fsck: commande introuvable
gfs2_fsck: command not found
gfs2_fsck: käsku ei ole
gfs2_fsck: không tìm thấy lệnh
gfs2_fsck: komanda nerasta
gfs2_fsck: Kommando nicht gefunden.
gfs2_fsck: kommandot finns inte
gfs2_fsck: komut yok
gfs2_fsck: nie znaleziono polecenia
gfs2_fsck: níor aimsíodh an t-ordú
gfs2_fsck: no se encontró la orden
gfs2_fsck: no s'ha trobat l'ordre
gfs2_fsck: opdracht niet gevonden
gfs2_fsck: parancs nem található
gfs2_fsck: perintah tidak ditemukan
gfs2_fsck: príkaz nenájdený
gfs2_fsck: příkaz nenalezen
gfs2_fsck: команда не найдена
gfs2_fsck: командата не е открита
gfs2_fsck: 命令找不到
gfs2_fsck: コマンドが見つかりません