linux – centos 7 merge sda1 and sdb1

In my CentOS 7 server, there is one disk and one partition (sda, sda1) .
now it is full, i asked from server provider to add new disk (sdb) then i created a partition sdb1 with LVM type .
how can i merge sda1 and sdb1 without loosing data or boot corruption ?

fdisk -l output :

Disk /dev/sda: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000ab236

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048    83886079    41942016   83  Linux

Disk /dev/sdb: 32.2 GB, 32212254720 bytes, 62914560 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x09a86f50

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048    62914559    31456256   8e  Linux LVM

df -h output :

Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        1.9G     0  1.9G   0% /dev
tmpfs           1.9G     0  1.9G   0% /dev/shm
tmpfs           1.9G  188M  1.7G  10% /run
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda1        40G   40G  623M  99% /
tmpfs           381M     0  381M   0% /run/user/54321
tmpfs           381M     0  381M   0% /run/user/0