Rebuild RAID1 Array on CENTOS 7 Server

A faulty disk in a RAID1 array (/dev/sdb) has been replaced with a new one. we need to copy the partition table from a healthy disk (sfdisk -d /dev/sda | sfdisk /dev/sdb ) and rebuild the RAID array (mdadm ) I am looking for someone who has previously done RAID synchronization in past and not someone who will search in internet for commands and paste them because a small mistake can completely erase data on server. Below is the current status of RAID array [root@sf1 ~]# cat /proc/mdstat Personalities : [raid1] md4 : active raid1 sda4[0] 1436365760 blocks [2/1] [U_] bitmap: 11/11 pages [44KB], 65536KB chunk md3 : active raid1 sda3[0] 511998912 blocks [2/1] [U_] bitmap: 4/4 pages [16KB], 65536KB chunk md2 : active raid1 sda2[0] 523200 blocks [2/1] [U_] unused devices: none ******************************** [root@sf1 ~]# fdisk -l Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes, 3907029168 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 WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion. Disk /dev/sda: 2000.4 GB, 2000398934016 bytes, 3907029168 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: gpt Disk identifier: B1F6BF42-4C91-4B8D-95EB-D9C48F37D73A # Start End Size Type Name 1 2048 1048575 511M EFI System primary 2 1048576 2095103 511M Linux RAID primary 3 2095104 1026093055 488.3G Linux RAID primary 4 1026093056 3898824703 1.3T Linux RAID primary 5 3898824704 3907014655 3.9G Linux swap primary Disk /dev/md2: 535 MB, 535756800 bytes, 1046400 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 /dev/md3: 524.3 GB, 524286885888 bytes, 1023997824 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 /dev/md4: 1470.8 GB, 1470838538240 bytes, 2872731520 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 **************************************