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SQL Server 2022 : Always On Availability Group2023/11/30

 
Configure Always On Availability Group for SQL Server on Linux.
This example is based on the environment like follows.
Secondaries are read-only replica Hosts on this settings.
-----------+-----------------------------+-----------------------------+------------
           |10.0.0.51                    |10.0.0.52                    |10.0.0.53
+----------+-----------+      +----------+-----------+      +----------+-----------+
| [ node01.srv.world ] |      | [ node02.srv.world ] |      | [ node03.srv.world ] |
|      (Primary)       |      |      (Secondary)     |      |      (Secondary)     |
|      SQL Server      |      |       SQL Server     |      |       SQL Server     |
+----------------------+      +----------------------+      +----------------------+

[1]
[2] On all Nodes, Enable Always On Availability Group feature and also Create a user for Database replication.
Replace [password] section to any password you like.
[root@node01 ~]#
/opt/mssql/bin/mssql-conf set hadr.hadrenabled 1

SQL Server needs to be restarted in order to apply this setting. Please run
'systemctl restart mssql-server.service'.
[root@node01 ~]#
systemctl restart mssql-server

[root@node01 ~]#
sqlcmd -S localhost -U SA

Password:
1> alter event session AlwaysOn_health on server with (startup_state=on);
2> go
1> create login dbm_login with password = 'P@ssw0rd01';
2> create user dbm_user for login dbm_login;
3> go
1> exit
[3] On all Nodes, Create certificate and copy it to other all Nodes and also Create an Endpoint.
Replace [password] section to any password you like.
[root@node01 ~]#
NODENAME=$(hostname -s)

[root@node01 ~]# cat > create-cert.sql <<EOF
create master key encryption by password = 'P@ssw0rd01';
create certificate ${NODENAME}_cert with subject = 'AG ${NODENAME} Certificate';
backup certificate ${NODENAME}_cert
to file = '/var/opt/mssql/data/${NODENAME}_cert.cer'
create endpoint AGEndpoint state = started
as tcp (listener_ip = all, listener_port = 5022)
for data_mirroring ( role = all, authentication = certificate ${NODENAME}_cert);
EOF 

[root@node01 ~]#
sqlcmd -S localhost -U SA -i create-cert.sql
[root@node01 ~]#
cd /var/opt/mssql/data

[root@node01 data]#
scp ${NODENAME}_cert.cer node02.srv.world:/var/opt/mssql/data/

dbm_certificate.cer                           100%  667   614.7KB/s   00:00
dbm_certificate.pvk                           100% 1212     1.0MB/s   00:00
[root@node01 data]#
scp ${NODENAME}_cert.cer node03.srv.world:/var/opt/mssql/data/

dbm_certificate.cer                           100%  667   581.6KB/s   00:00
dbm_certificate.pvk                           100% 1212   935.1KB/s   00:00
[root@node01 data]#
ssh node02.srv.world "chown mssql:mssql /var/opt/mssql/data/${NODENAME}_cert.cer"

[root@node01 data]#
ssh node03.srv.world "chown mssql:mssql /var/opt/mssql/data/${NODENAME}_cert.cer"
# if Firewalld is running, allow endpoint port

[root@node01 data]#
firewall-cmd --add-port=5022/tcp

[root@node01 data]#
firewall-cmd --runtime-to-permanent
[4] On all Nodes, Restore certificates that are copied from other Nodes.
[root@node01 ~]# cat > restore-cert.sql <<EOF
create certificate node02_cert authorization dbm_user
from file = '/var/opt/mssql/data/node02_cert.cer'
create certificate node03_cert authorization dbm_user
from file = '/var/opt/mssql/data/node03_cert.cer'
grant connect on endpoint::AGEndpoint to dbm_login;
EOF 

[root@node01 ~]#
sqlcmd -S localhost -U SA -i restore-cert.sql

[5] On primary Node, Configure Availability Group.
[root@node01 ~]# cat > create-ag.sql <<'EOF'
create availability group [AG01]
with (cluster_type = none)
for replica on
N'node01' with (
endpoint_url = N'tcp://10.0.0.51:5022',
availability_mode = asynchronous_commit,
failover_mode = manual,
seeding_mode = automatic,
primary_role (read_only_routing_list=(('node02','node03'), 'node01')),
secondary_role (
allow_connections = read_only,
read_only_routing_url = N'tcp://10.0.0.51:1433')),
N'node02' with (
endpoint_url = N'tcp://10.0.0.52:5022',
availability_mode = asynchronous_commit,
failover_mode = manual,
seeding_mode = automatic,
primary_role (read_only_routing_list=(('node01','node03'), 'node02')),
secondary_role (
allow_connections = read_only,
read_only_routing_url = N'tcp://10.0.0.52:1433')),
N'node03' with (
endpoint_url = N'tcp://10.0.0.53:5022',
availability_mode = asynchronous_commit,
failover_mode = manual,
seeding_mode = automatic,
primary_role (read_only_routing_list=(('node01','node02'), 'node03')),
secondary_role (
allow_connections = read_only,
read_only_routing_url = N'tcp://10.0.0.53:1433'));
alter availability group [AG01] grant create any database;
EOF 

[root@node01 ~]#
sqlcmd -S localhost -U SA -i create-ag.sql
[6] On all secondary Nodes, Join in Availability Group.
[root@node02 ~]#
sqlcmd -S localhost -U SA

Password:
1> alter availability group [AG01] join with (cluster_type = none);
2> alter availability group [AG01] grant create any database;
3> go
1> exit
[7] On primary Node, Add listener and database to Availability Group.
[root@node01 ~]# cat > create-db.sql <<'EOF'
alter availability group [AG01] add listener 'AG01_listener'
( with ip (
('10.0.0.51', '255.255.255.0') ), port = 1433);
create database [AG01_DB];
alter database [AG01_DB] set recovery full;
backup database [AG01_DB] to disk = N'/var/opt/mssql/data/AG01_DB.bak';
alter availability group [AG01] add database [AG01_DB];
EOF 

[root@node01 ~]#
sqlcmd -S localhost -U SA -i create-db.sql

Password:
Processed 344 pages for database 'AG01_DB', file 'AG01_DB' on file 1.
Processed 1 pages for database 'AG01_DB', file 'AG01_DB_log' on file 1.
BACKUP DATABASE successfully processed 345 pages in 0.124 seconds (21.685 MB/sec).
# confirm accessible to database on secondary node

[root@node01 ~]#
sqlcmd -S node02 -U SA -Q 'select name, create_date from sys.databases where name = "AG01_DB"'

Password:
name                      create_date
------------------------- -----------------------
AG01_DB                   2023-11-30 09:17:11.743

(1 rows affected)
[8] That's OK. Verify it works normally to access to the listener and database.
[root@node01 ~]#
sqlcmd -S localhost -U SA

Password:

# current state
1> select L.replica_id,L.replica_server_name,R.role_desc from sys.availability_replicas as L
2> left join sys.dm_hadr_availability_replica_states as R on L.replica_id = R.replica_id
3> go
replica_id                           replica_server_name           role_desc
------------------------------------ ----------------------------- ------------------------
BBACCFF7-CE2F-450C-8491-35E317F3774F node01                        PRIMARY
94C43733-1700-46AD-B83B-CD239AC3DE2A node02                        SECONDARY
C9AF419A-BC17-463D-80DD-102D6E7BB2B7 node03                        SECONDARY

(3 rows affected)

1> exit

# read-only access is responded by secondary replica

[root@node01 ~]#
sqlcmd -S 10.0.0.51 -U SA -K readonly -d AG01_DB -Q 'select @@servername'

Password:
-------------
node03

(1 rows affected)
# read-only access is responded by secondary replica (round robin routing)

[root@node01 ~]#
sqlcmd -S 10.0.0.51 -U SA -K readonly -d AG01_DB -Q 'select @@servername'

Password:
-------------
node02

(1 rows affected)
# primary replica responds to non-read-only access

[root@node01 ~]#
sqlcmd -S 10.0.0.51 -U SA -d AG01_DB -Q 'select @@servername'

Password:
--------------
node01

(1 rows affected)
[9] It's possible to verify or change state of [Always On AG] with SSMS on Windows client.
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