In most cases, fully resizing an online logical unit involves two things: resizing the logical unit itself and reflecting the size change in the corresponding multipath device (if multipathing is enabled on the system).
To resize the online logical unit, start by modifying the logical unit size through the array management interface of your storage device. This procedure differs with each array; as such, consult your storage array vendor documentation for more information on this.
In order to resize an online file system, the file system must not reside on a partitioned device.
37.1. Resizing Fibre Channel Logical Units
After modifying the online logical unit size, re-scan the logical unit to ensure that the system detects the updated size. To do this for Fibre Channel logical units, use the following command:
$ echo 1 > /sys/block/sdX/device/rescan
To re-scan fibre channel logical units on a system that uses multipathing, execute the aforementioned command for each sd device (i.e.
sd2, and so on) that represents a path for the multipathed logical unit. To determine which devices are paths for a multipath logical unit, use
multipath -ll; then, find the entry that matches the logical unit being resized. It is advisable that you refer to the WWID of each entry to make it easier to find which one matches the logical unit being resized.