My post will be about log shipping because setting up log shipping using the GUI is a very tedious task and doing it with TSQL scripting is no fun either. So let’ see how we can do this with PowerShell.
Log shipping explained
If you’ve been a SQL Server DBA for a while you probably heard about log shipping.
Log shipping makes it possible to increase the database’s availability by automatically backing up the the transaction log, copying the backup file and restoring the backup file to another database instance (or the same instance with a different database name).
Log shipping is an older technology but still has a purpose in lots of environments where it’s being used for reporting, ETL or to give developers and users access to production without the risk of them breaking anything.
Why use PowerShell
If you’ve ever had to setup log shipping in the SQL Server Management Studio (SSMS) than you know how tedious it can be. I actually counted the amount of clicks to setup a single database for log shipping and you need about 40 of them to get the job done.
So one day we decided to create a warm standby for one of our production servers. I had setup log shipping before and if you know what to do it’s not that difficult.
It becomes a problem when you have to setup log shipping for more than 20 databases ranging from 10 GB to 800 GB in size.
I ended up spending about a week setting it up (between other tasks I do have more work to do) and for me that’s way too much time for something as simple as this.
So why use PowerShell, because anything I can do with the SSMS can be done with the SMO. This would save a lot of time for me and anyone using the the functionality.
How did I do it
I contacted Chrissy LeMaire who is the original brainchild of the dbatools PowerShell module and she was instantly excited to have this functionality within the module.
The first thing I had to do was to find out how SQL Server in the background setup the log shipping when I used the GUI. Yeah I know using the GUI is bad when you use a lot of PowerShell but sometimes I like to do it old school.
I quickly found out that SQL Server does a lot of things to set up log shipping. It creates jobs, job steps, job schedules, uses stored procedures to set values in specific tables etc etc.
I went to the dbatools module and used the Find-DbaCommand function to see if there was any functionality to create the agent objects (jobs, steps and schedules) but they weren’t there so the first step was to create a full set of functions to manage those objects.
A couple of thousand lines later I finished the agent functionality and could continue to developing the log shipping function.
That function started pretty small, but like the agent functionality, quickly grew to be some sort of monster with over 70 different parameters that would support every kind of situation.
After about a couple of hundred iterations it was finally committed to the development branch of the dbatools module to get tested. I have great respect for the people who did the testing of that functionality because I didn’t envy them. I knew how complicated it was to build everything and to test all that must have been a lot of work. Thank you to all the testers that accepted the challenge.
The entire log shipping functionality is now separated between 5 functions. Four of them are used internally and are not visible as a public function because you can easily break stuff if it’s not being used correctly.
The main function, Invoke-DbaLogShipping, is available in the dbatools module for anyone to use.
If you open the GUI for the log shipping you have lots of choices but most of them are already supplied in the GUI itself and you can decide whether to use them or not.
The whole idea behind the functionality was that yit would allow you to quickly setup log shipping using a lot of defaults like you can in the GUI, but if you’re more experienced you can change any setting to your preferences.
it will take you about a minute to set all the parameters and after that the only action that will slow you down is the size of you database files when you use a restore.
Enough talk I want to see some action!
I will demonstrate how to setup log shipping using the least amount of parameters. You actually need six parameters to make it work:
- SourceSqlInstance – Which instance need to be used as the source server)
- DestinationSqlInstance – Which server needs to be used to log ship the database too
- BackupNetworkPath – Where do the backup need to be placed
- Database – Which database, or databases, needs to be log shipped
- GenerateFullBackup or UseExistingFullBackup – Generate a full backup or use an existing one
The command below will log ship a database from server1 to server2.
It will log ship one database called db1.
The network path for the backups is \\server1\logshipping\backup.
The backups will be created with backup compression.
No new backup will be created, instead it will use the last full backup
In this example the suffix for the database is “LS” because I want to differentiate the log shipped databases.
Invoke-DbaLogShipping -SourceSqlInstance server1 -DestinationSqlInstance server2 -Database db1 -BackupNetworkPath \\server1\logshipping\backup -CompressBackup -UseExistingFullBackup -SecondaryDatabaseSuffix LS
Below is the result of the log shipping.
What else can be done with this function?
When I developed this function it had a lot of iterations. I’m a developer that will have a good idea what to build and during the process will think of other functionality that needs to be put in.
I had a lot of iterations where I constantly thought of new ideas that would make other people’s work easier.
A couple of examples:
- To monitor or not to monitor log shipping
- Enabled or disabled log shipping jobs
- Naming convention of the jobs
- Standby or read-only mode for the secondary database
- To compress or not to compress the backup files
- Generate a full backup for initialization
- Log ship multiple databases in one command. This will be executed in serial.
- Force every setting and discard anything that’s there
The last one needs a little more explanation. I want this function to work really easy and with existing settings I want it to work. The -Force parameter is a really powerful parameter which will assume a lot of the defaults but will also overwrite existing settings like jobs, schedules, database settings etc.
I will never ever use the GUI again to setup log shipping again and I hope you will too. It’s just way too much work and I’ve had it fail on my lots of times not knowing what went wrong having to set everything up from scratch.
There is more functionality coming for the log shipping functions like status checks and fail-over initialization.
If you find that something is missing, or works inefficient or doesn’t work (I hope not), in this function please let us know. You can find us on Slack, GitHub, Twitter, YouTube, LinkedIn. You can find me on on the Slack channel most of the time. If you have any questions you know where to find me.
The last thing I want to say is that dbatools module is a community driven module that enables database administrators to work more efficient. It’s because of the hard work of all the volunteers that this module is such a success.
It’s a group of very hard working and smart people who I have great respect for. It is because of the enthusiasm of all those people, and especially Chrissy, that I love working on the module.
Thank you again Rob for hosting this month’s TSQL Tuesday, it was really fun.