@SpoonyLove @olivierlambert
For usb passthrough we are using USB redirector over network
For anything storage related we use something like this:
mkdir /adm/passSR
passUUID=`xe sr-create name-label="Direct access SR" name-description="Direct acces to hdd with simlink" type=udev content-type=disk device-config:location=/adm/passSR`
ln -s /dev/sdb /adm/passSR/sdb
xe sr-scan uuid=$passUUID
xe vdi-list sr-uuid=$passUUID
Remember to replace /dev/sdb with your device.