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Get started with log shipping on Linux

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Applies to: SQL Server - Linux

Log shipping is a SQL Server high availability (HA) configuration where a database from a primary server is replicated onto one or more secondary servers. Log shipping allows backup files from the source database to restore onto the secondary server. The primary server creates transaction log backups periodically, and the secondary servers restore them, updating the secondary copy of the database.

Diagram showing the log shipping workflow.

As described in the previous diagram, a log shipping session involves the following steps:

  • Backing up the transaction log file on the primary SQL Server instance
  • Copying the transaction log backup file across the network to one or more secondary SQL Server instances
  • Restoring the transaction log backup file on the secondary SQL Server instances

Prerequisites

Set up a network share for log shipping using CIFS

Note

This tutorial uses CIFS + Samba to setup the network share.

Configure primary server

  1. Install Samba with the following command:

    • For Red Hat Enterprise Linux (RHEL):

      sudo yum -y install samba

    • For Ubuntu:

      sudo apt-get install samba

  2. Create a directory to store the logs for log shipping, and give the mssql user the required permissions:

    mkdir /var/opt/mssql/tlogs
chown mssql:mssql /var/opt/mssql/tlogs
chmod 0700 /var/opt/mssql/tlogs

  3. Edit the /etc/samba/smb.conf file (you need root permissions), and add the following section:

    [tlogs]
path=/var/opt/mssql/tlogs
available=yes
read only=yes
browsable=yes
public=yes
writable=no

  4. Create a mssql user for Samba:

    sudo smbpasswd -a mssql

  5. Restart the Samba services:

    sudo systemctl restart smbd.service nmbd.service

Configure secondary server

  1. Install the CIFS client with the following command:

    • For RHEL:

      sudo yum -y install cifs-utils

    • For Ubuntu:

      sudo apt-get install cifs-utils

  2. Create a file to store your credentials. In this example, we use /var/opt/mssql/.tlogcreds. Use the password you recently set for your mssql Samba account, and replace <domain>:

    username=mssql
domain=<domain>
password=<password>

  3. Run the following commands to create an empty directory for mounting and set permission and ownership correctly

    mkdir /var/opt/mssql/tlogs
sudo chown root:root /var/opt/mssql/tlogs
sudo chmod 0550 /var/opt/mssql/tlogs
sudo chown root:root /var/opt/mssql/.tlogcreds
sudo chmod 0660 /var/opt/mssql/.tlogcreds

  4. Add the line to etc/fstab to persist the share. Replace <ip_address_of_primary_server> with the appropriate value:

    //<ip_address_of_primary_server>/tlogs /var/opt/mssql/tlogs cifs credentials=/var/opt/mssql/.tlogcreds,ro,uid=mssql,gid=mssql 0 0

  5. Mount the shares:

    sudo mount -a

Set up log shipping using Transact-SQL

  1. Back up the database on the primary server:

    BACKUP DATABASE SampleDB
    TO DISK = '/var/opt/mssql/tlogs/SampleDB.bak';
GO

  2. Configure log shipping on the primary server:

    DECLARE @LS_BackupJobId AS UNIQUEIDENTIFIER;
DECLARE @LS_PrimaryId AS UNIQUEIDENTIFIER;
DECLARE @SP_Add_RetCode AS INT;

EXECUTE
    @SP_Add_RetCode = master.dbo.sp_add_log_shipping_primary_database
    @database = N'SampleDB',
    @backup_directory = N'/var/opt/mssql/tlogs',
    @backup_share = N'/var/opt/mssql/tlogs',
    @backup_job_name = N'LSBackup_SampleDB',
    @backup_retention_period = 4320,
    @backup_compression = 2,
    @backup_threshold = 60,
    @threshold_alert_enabled = 1,
    @history_retention_period = 5760,
    @backup_job_id = @LS_BackupJobId OUTPUT,
    @primary_id = @LS_PrimaryId OUTPUT,
    @overwrite = 1;

IF (@@ERROR = 0
    AND @SP_Add_RetCode = 0)
    BEGIN
        DECLARE @LS_BackUpScheduleUID AS UNIQUEIDENTIFIER;
        DECLARE @LS_BackUpScheduleID AS INT;
                EXECUTE msdb.dbo.sp_add_schedule
            @schedule_name = N'LSBackupSchedule',
            @enabled = 1,
            @freq_type = 4,
            @freq_interval = 1,
            @freq_subday_type = 4,
            @freq_subday_interval = 15,
            @freq_recurrence_factor = 0,
            @active_start_date = 20170418,
            @active_end_date = 99991231,
            @active_start_time = 0,
            @active_end_time = 235900,
            @schedule_uid = @LS_BackUpScheduleUID OUTPUT,
            @schedule_id = @LS_BackUpScheduleID OUTPUT;
                EXECUTE msdb.dbo.sp_attach_schedule
            @job_id = @LS_BackupJobId,
            @schedule_id = @LS_BackUpScheduleID;
                EXECUTE msdb.dbo.sp_update_job
            @job_id = @LS_BackupJobId,
            @enabled = 1;
    END

EXECUTE master.dbo.sp_add_log_shipping_alert_job;

EXECUTE master.dbo.sp_add_log_shipping_primary_secondary
    @primary_database = N'SampleDB',
    @secondary_server = N'<ip_address_of_secondary_server>',
    @secondary_database = N'SampleDB',
    @overwrite = 1;

  3. Restore the database on the secondary server:

    RESTORE DATABASE SampleDB FROM DISK = '/var/opt/mssql/tlogs/SampleDB.bak'
    WITH NORECOVERY;

  4. Configure log shipping on the secondary server:

    DECLARE @LS_Secondary__CopyJobId AS UNIQUEIDENTIFIER;
DECLARE @LS_Secondary__RestoreJobId AS UNIQUEIDENTIFIER;
DECLARE @LS_Secondary__SecondaryId AS UNIQUEIDENTIFIER;
DECLARE @LS_Add_RetCode AS INT;

EXECUTE
    @LS_Add_RetCode = master.dbo.sp_add_log_shipping_secondary_primary
    @primary_server = N'<ip_address_of_primary_server>',
    @primary_database = N'SampleDB',
    @backup_source_directory = N'/var/opt/mssql/tlogs/',
    @backup_destination_directory = N'/var/opt/mssql/tlogs/',
    @copy_job_name = N'LSCopy_SampleDB',
    @restore_job_name = N'LSRestore_SampleDB',
    @file_retention_period = 4320,
    @overwrite = 1,
    @copy_job_id = @LS_Secondary__CopyJobId OUTPUT,
    @restore_job_id = @LS_Secondary__RestoreJobId OUTPUT,
    @secondary_id = @LS_Secondary__SecondaryId OUTPUT;

IF (@@ERROR = 0
    AND @LS_Add_RetCode = 0)
    BEGIN
        DECLARE @LS_SecondaryCopyJobScheduleUID AS UNIQUEIDENTIFIER;
        DECLARE @LS_SecondaryCopyJobScheduleID AS INT;
                EXECUTE msdb.dbo.sp_add_schedule
            @schedule_name = N'DefaultCopyJobSchedule',
            @enabled = 1,
            @freq_type = 4,
            @freq_interval = 1,
            @freq_subday_type = 4,
            @freq_subday_interval = 15,
            @freq_recurrence_factor = 0,
            @active_start_date = 20170418,
            @active_end_date = 99991231,
            @active_start_time = 0,
            @active_end_time = 235900,
            @schedule_uid = @LS_SecondaryCopyJobScheduleUID OUTPUT,
            @schedule_id = @LS_SecondaryCopyJobScheduleID OUTPUT;
                EXECUTE msdb.dbo.sp_attach_schedule
            @job_id = @LS_Secondary__CopyJobId,
            @schedule_id = @LS_SecondaryCopyJobScheduleID;
        DECLARE @LS_SecondaryRestoreJobScheduleUID AS UNIQUEIDENTIFIER;
        DECLARE @LS_SecondaryRestoreJobScheduleID AS INT;
                EXECUTE msdb.dbo.sp_add_schedule
            @schedule_name = N'DefaultRestoreJobSchedule',
            @enabled = 1,
            @freq_type = 4,
            @freq_interval = 1,
            @freq_subday_type = 4,
            @freq_subday_interval = 15,
            @freq_recurrence_factor = 0,
            @active_start_date = 20170418,
            @active_end_date = 99991231,
            @active_start_time = 0,
            @active_end_time = 235900,
            @schedule_uid = @LS_SecondaryRestoreJobScheduleUID OUTPUT,
            @schedule_id = @LS_SecondaryRestoreJobScheduleID OUTPUT;
                EXECUTE msdb.dbo.sp_attach_schedule
            @job_id = @LS_Secondary__RestoreJobId,
            @schedule_id = @LS_SecondaryRestoreJobScheduleID;
    END

DECLARE @LS_Add_RetCode2 AS INT;

IF (@@ERROR = 0
    AND @LS_Add_RetCode = 0)
    BEGIN
                EXECUTE
            @LS_Add_RetCode2 = master.dbo.sp_add_log_shipping_secondary_database
            @secondary_database = N'SampleDB',
            @primary_server = N'<ip_address_of_primary_server>',
            @primary_database = N'SampleDB',
            @restore_delay = 0,
            @restore_mode = 0,
            @disconnect_users = 0,
            @restore_threshold = 45,
            @threshold_alert_enabled = 1,
            @history_retention_period = 5760,
            @overwrite = 1;
    END

IF (@@ERROR = 0
    AND @LS_Add_RetCode = 0)
    BEGIN
                EXECUTE msdb.dbo.sp_update_job
            @job_id = @LS_Secondary__CopyJobId,
            @enabled = 1;
                EXECUTE msdb.dbo.sp_update_job
            @job_id = @LS_Secondary__RestoreJobId,
            @enabled = 1;
    END

Verify log shipping works

  1. Verify that log shipping works by starting the following job on the primary server:

    USE msdb;
GO

EXECUTE dbo.sp_start_job N'LSBackup_SampleDB';
GO

  2. Verify that log shipping works by starting the following job on the secondary server:

    USE msdb;
GO

EXECUTE dbo.sp_start_job N'LSCopy_SampleDB';
GO

EXECUTE dbo.sp_start_job N'LSRestore_SampleDB';
GO

  3. Verify that log shipping failover works by executing the following command:

    Warning

    This command will bring the secondary database online and break the log shipping configuration. You need to reconfigure log shipping after running this command.

    RESTORE DATABASE SampleDB
    WITH RECOVERY;

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