Hello Sofia Enriquez, Thank you for you help
Below is the cinder.conf we are using.
Unity-1 backend works normally, and an error occurs when using Unity-2 backend.

[DEFAULT]
debug = False
log_dir = /var/log/kolla/cinder
use_forwarded_for = true
use_stderr = False
my_ip = 10.8.6.31
volume_name_template = volume-%s
glance_api_servers = http://10.8.6.34:9292 [10.8.6.34]
glance_num_retries = 3
glance_ca_certificates_file =
enabled_backends = rbd-1,unity-1,unity-2
default_volume_type = unity-1
api_paste_config = /etc/cinder/api-paste.ini
auth_strategy = keystone
transport_url = rabbit://openstack:uW9Ajepp24xdDAuuS2XLZFHc2hACUOsyzLuX5Ibp@10.8.6.31:5672 [10.8.6.31],openstack:uW9Ajepp24xdDAuuS2XLZFHc2hACUOsyzLuX5Ibp@10.8.6.32:5672 [10.8.6.32],openstack:uW9Ajepp24xdDAuuS2XLZFHc2hACUOsyzLuX5Ibp@10.8.6.33:5672// [10.8.6.33]
rpc_response_timeout = 600
sf_volume_create_timeout = 600
enable_force_upload = True
cinder_internal_tenant_project_id = c2f467630b56446a98b5741bd8d4c43c
cinder_internal_tenant_user_id = 6bbc0a2aa3c04b39ae780c19e9308e44

[oslo_messaging_notifications]
transport_url = rabbit://openstack:uW9Ajepp24xdDAuuS2XLZFHc2hACUOsyzLuX5Ibp@10.8.6.31:5672 [10.8.6.31],openstack:uW9Ajepp24xdDAuuS2XLZFHc2hACUOsyzLuX5Ibp@10.8.6.32:5672 [10.8.6.32],openstack:uW9Ajepp24xdDAuuS2XLZFHc2hACUOsyzLuX5Ibp@10.8.6.33:5672// [10.8.6.33]
driver = messagingv2
topics = notifications

[oslo_messaging_rabbit]
heartbeat_in_pthread = False

[oslo_middleware]
enable_proxy_headers_parsing = True

[nova]
interface = internal
auth_url = http://10.8.6.34:5000 [10.8.6.34]
auth_type = password
project_domain_id = default
user_domain_id = default
region_name = RegionOne
project_name = service
username = nova
password = HJbEXHAeKJf7RV94wyMqPiIxrQwdpLG4DGXpjtCr
cafile =

[database]
connection = mysql+pymysql://cinder:jMMyTCaLq9pac4VZxeqtVa1UD16QEErp1vGuSCNh@10.8.6.34:3306/cinder [10.8.6.34]
connection_recycle_time = 10
max_pool_size = 1
max_retries = -1

[keystone_authtoken]
service_type = volume
www_authenticate_uri = http://10.8.6.34:5000 [10.8.6.34]
auth_url = http://10.8.6.34:5000 [10.8.6.34]
auth_type = password
project_domain_id = default
user_domain_id = default
project_name = service
username = cinder
password = Dyc0c1rMNGZM3Q2c67YtDfaIavZeSORxvMLVwNDu
cafile =
region_name = RegionOne
memcache_security_strategy = ENCRYPT
memcache_secret_key = vrfWidmR3y8VNIJopg9HZxWxWl4PWalxAjVgUJlC
memcached_servers = 10.8.6.31:11211 [10.8.6.31],10.8.6.32:11211 [10.8.6.32],10.8.6.33:11211 [10.8.6.33]

[oslo_concurrency]
lock_path = /var/lib/cinder/tmp

[rbd-1]
volume_driver = cinder.volume.drivers.rbd.RBDDriver
volume_backend_name = rbd-1
rbd_pool = cinder-volumes
rbd_ceph_conf = /etc/ceph/ceph.conf
rados_connect_timeout = 5
rbd_user = cinder
rbd_secret_uuid = f2937a79-6827-4924-ac32-5155706013ad
report_discard_supported = True

[unity-1]
# Storage protocol
storage_protocol = FC
# Unisphere IP
san_ip = 172.19.254.56
# Unisphere username and password
san_login = admin
san_password = P@ssw0rd
# Volume driver name
volume_driver = cinder.volume.drivers.dell_emc.unity.Driver
# backend's name
volume_backend_name = Storage_FC_01
image_volume_cache_enabled = True

[unity-2]
# Storage protocol
storage_protocol = FC
# Unisphere IP
san_ip = 172.19.254.57
# Unisphere username and password
san_login = admin
san_password = P@ssw0rd
# Volume driver name
volume_driver = cinder.volume.drivers.dell_emc.unity.Driver
# backend's name
volume_backend_name = Storage_FC_02
image_volume_cache_enabled = True

[privsep_entrypoint]
helper_command = sudo cinder-rootwrap /etc/cinder/rootwrap.conf privsep-helper --config-file /etc/cinder/cinder.conf

[barbican]
auth_endpoint = http://10.8.6.34:5000 [10.8.6.34]
barbican_endpoint_type = internal
verify_ssl_path =

[coordination]