hello adym,

please check with the commands fdisk -l, lsblk and multipath -l if the size of the LUN is recognized correctly

after that you will have to
- increase the size of the physical partition
- increase the size of the logical volume (if there is one)
- increase the size of the file system on the logical volume / physical partition

in this particular order.

Please be careful - especially when using logical volume management - because if you are doing it wrong you can destroy your whole data. So if possible, first make a full image or snapshot of your hard disks.