lvcreate: 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/lvcreate - from package: lvm2

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

On Debian possible default full paths are:

/sbin/lvcreate - from package: lvm2

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

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