corosync-notifyd: command not found

Have You tried accessing the binary with the full path?

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/sbin/corosync-notifyd - from package: corosync

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

On Debian possible default full paths are:

/usr/sbin/corosync-notifyd - from package: corosync
/usr/lib/debug/usr/sbin/corosync-notifyd - from package: corosync-dbg

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