I expanded a LUN on my SAN (from 30G to 50G), and tried all kind of voodoo but it looks like the system still believes the device is still small, despite showing me the new size alright.

# blockdev --getsize64 /dev/sdl
53687091200
# dd if=/dev/sdl skip=$(( 31*1024*1024*1024/512 )) count=1|hexdump -C
dd: reading `/dev/sdl': Input/output error

The dd line works for blocks below the 30G original size.

If I reboot, the problem goes away, but I don't want to since the machine has a dozen VMs running.

I tried various magic, such as:

iscsiadm -m node -R -I iface0

... to no avail.

Note: I'm not using multipath.