lvmdiskscan: 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/lvmdiskscan - from package: lvm2

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

On Debian possible default full paths are:

/sbin/lvmdiskscan - from package: lvm2

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

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