SD card user 1000, can't chown to root

Andrelec1

i have a large nodejs project ... so i put a 2go micro sd in my omega 2+

i make folder like : mkdir /sd
i mount the sd card in : mount /tmp/mounts/SD-P1 /sd

i create a file ~/.npmrc with the following content :
prefix="/sd/.npm-global"
cache="/sd/.npm-cache"

but when i try nmp install jethro ( same result with all dependances )
i result error :

npm ERR! Linux 4.4.46
npm ERR! argv "/usr/bin/node" "/usr/bin/npm" "install" "github:sdesalas/node-serialport-omega2"
npm ERR! node v4.3.1
npm ERR! npm v2.14.12
npm ERR! path /sd/.npm-cache/_git-remotes/_templates
npm ERR! code EPERM
npm ERR! errno -1
npm ERR! syscall chown

npm ERR! Error: EPERM: operation not permitted, chown '/sd/.npm-cache/_git-remotes/_templates'
npm ERR! at Error (native)
npm ERR! { [Error: EPERM: operation not permitted, chown '/sd/.npm-cache/_git-remotes/_templates']
npm ERR! errno: -1,
npm ERR! code: 'EPERM',
npm ERR! syscall: 'chown',
npm ERR! path: '/sd/.npm-cache/_git-remotes/_templates' }
npm ERR!
npm ERR! Please try running this command again as root/Administrator.

npm ERR! Please include the following file with any support request:
npm ERR! /sd/project/npm-debug.log

so after rigth check, i see my /sd folder is a 1000:1000 file -_-" ...
i try chown root:root /sd but permission denied ....

Andrelec1

Format microSD in EXT2 and probleme solve