isnsdd: 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/sbin/isnsdd - from package: isns-utils

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

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