Unable to extend logical partition after adding new hard disks into an existing RAID5 array

Hi,

We have a ProLiant DL360 Gen9 with a Smart Array Controller containing 5 x 300GB 12G SAS drives configured in to 1 logical drive using RAID 5. I have added 3 new drives of identical type the the first 5 and want to use it to expand the size of the current RAID array. After adding such drivers using the HP Smart Storage Administrator, in Redhat 6 using parted or gdisk , there is no extended space in the current logical drive.

Here is the Before and After results in my server using command gdisk /dev/sda

Before:

Number Start (sector) End (sector) Size Code Name
1 2048 2099199 1024.0 MiB EF00
2 2099200 4196351 1024.0 MiB 0700
3 4196352 37750783 16.0 GiB 8200
4 37750784 2343486010 1.1 TiB 8E00 Linux LVM => note that the started sector No 37750784, with current size = 1.1 TiB

After:

Number Start (sector) End (sector) Size Code Name
1 2048 2099199 1024.0 MiB EF00
2 2099200 4196351 1024.0 MiB 0700
3 4196352 37750783 16.0 GiB 8200
4 37750784 2343486010 1.1 TiB 8E00 Linux LVM

Any idea so to fix this issue?

Thx in advance,

Trung