RAID1 / CentOS - I can not remove a faulty disk and connect the good disk

This server (has RAID 1 – SoftRAID with CentOS) has been delayed by deleting a cache of 290,000 files last week, and yesterday when performing manual backup of the machine via tar.gz, it failed and when restarting it did not return. Now I want to leave / dev / sdb (where it has no faults) in the air, and turn off / dev / sda, and wait for the provider to change the disk (/ dev / sda).

In recovery mode it shows that / dev / sda has a problem (according to image):

Note: Running smartctl -a on each ssd (https://pastebin.com/a7ssE88T) also verifies that / dev / sda is defective, and / dev / sdb is normal.

In recovery mode, I try to run:

root @ rescue: ~ # cat / proc / mdstat
Personalities: [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty]
unused devices: <none>

Even running fdisk -l, I have this return:

This is my recovery environment:

root @ rescue: ~ # df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 24G 0 24G 0% / dev
198.27.85.63:/home/pub/rescue.v8 846G 352G 451G 44% / nfs
tmpfs 24G 3.2M 24G 1% / rw
aufs 24G 3.2M 24G 1% /
198.27.85.63:/home/pub/pro-power 846G 352G 451G 44% / power
198.27.85.63:/home/pub/commonnfs 846G 352G 451G 44% / common
tmpfs 24G 0 24G 0% / dev / shm
tmpfs 24G 10M 24G 1% / run
tmpfs 5.0M 0 5.0M 0% / run / lock
tmpfs 24G 0 24G 0% / sys / fs / cgroup
tmpfs 24G 16K 24G 1% / tmp

If I try to mount the 2 disks:

root @ rescue: ~ # mount / dev / sdb / mnt /
NTFS signature is missing.
Failed to mount '/ dev / sdb': Invalid argument
The device '/ dev / sdb' does not seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. / dev / sda, not / dev / sda1)? Or the other way around?
root @ rescue: ~ # mount / dev / sda / mnt /
Error reading bootsector: Input / output error
Failed to mount '/ dev / sda': Input / output error
NTFS is either inconsistent, or there is a hardware fault, or it's a
SoftRAID / FakeRAID hardware. In the first case run chkdsk / f on Windows
then reboot into Windows twice. The usage of the / f parameter is very
important If the device is a SoftRAID / FakeRAID then first activate
it and mount a different device under the / dev / mapper / directory, (e.g.
/ dev / mapper / nvidia_eahaabcc1). Please see the 'dmraid' documentation
for more details.