vgconvert: 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/vgconvert - from package: lvm2

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

On Debian possible default full paths are:

/sbin/vgconvert - from package: lvm2

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

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