We want everyone to know about this module. Chrissy LeMaire reached out to me and asked if I could write some tests for the log shipping part and I did.
Because I wrote the log shipping commands for dbatools I was excited about creating a test that could be implemented into this module for everyone to use.
That test is also quite easy to use, as Sander demonstrates.
Initially log shipping was meant to be used as a warm standby. You have your data on another instance but you still have some human intervention to get it all back up.
Imagine the following situation. You have setup log shipping using either the GUI or the commands in dbatools. You have about 15 databases and everything is working fine.
Until one day the primary instance goes down and is not recoverable. For the production to continue you have to bring the log shipped databases online fast.
You have to figure what the last transaction log backup was. You have to check if it was copied to the secondary instance and if it’s restored.
To do this by running a couple of queries, copying the files if needed and run the log shipping jobs takes time. I’d rather run a command and recover one or more databases and get back to the problem of the primary instance.
Read on to see how to use dbatools to recover a log shipped database.
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 it 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.
Read on for an example of how to use this. It looks pretty snazzy.
On the primary server, multiple Agent jobs take backups simultaneously across lots of databases using Ola Hallengren’s proven DatabaseBackup proc. You control the backup frequency and the number of Agent jobs to balance recoverability against performance overhead.
On the restoring server, same thing, but with sp_DatabaseRestore – multiple Agent jobs watch folders for incoming files, and restore ’em. Just like with regular log shipping, you can control the job schedules, so you can use the servers for read-only reporting workloads during the day, then catch ’em back up to current overnight.
You can install the restore side of it on multiple servers, in multiple locations, too.
This looks like a very interesting project for automating DR solutions.
This topic has come up several times recently, so I feel the need to blog on it. As the person who wrote the book on Database Mirroring, it will probably come as a surprise to many of you that I believe that log shipping is a much better tool for database migrations than database mirroring.
I’m not just talking about the fact that database mirroring is deprecated (since SQL Server 2012) and log shipping is not. Both are still in SQL Server to this day. Because database mirroring is deprecated, it is no longer receiving bug fixes (except maybe critical security bugs) and no work is being done to make sure that it works with new features in current and future versions. Log shipping is still receiving both of these things. I will lay out the real reasons below.
Robert makes two compelling arguments in favor of log shipping.
What I’m going to do is setup two instances of SQL Server running on linux and log ship one database from one to another. So the first thing I did was get two VMs running Ubuntu 16.04.1 LTS which can be download from here.
Once both servers were setup (remember to enable ssh) I then went about getting SQL setup, I’m not going to go through the install in this post as the process is documented fully here. Don’t forget to also install the SQL Tools, full guide is here.
Read on for the guide, but also be sure to read his disclaimer.
To resolve this, you can restore files under NORECOVERY, then switch to STANDBY: when restoring a log backup, you have two restore choices: NORECOVERY and STANDBY. Both these choices will allow further log restores, but STANDBY is the option to choose if you want the database to be read-only. NORECOVERY leaves the database in a transactionally inconsistent state: it does not roll back uncommitted transactions into a tuf file. So it is possible to restore the log files in NORECOVERY mode, and then restore a final log with the STANDBY option to enable the database to be read-only (it is pretty neat that you can switch between STANDBY and NORECOVERY in this way.) We can do this because we honestly don’t care about all those in-between restores being transactionally consistent. Sadly, this option is not an out-the-box operation, and so requires writing a custom job to restore the log files. I’ve read online a few methods to achieve this, and I have written my own custom restore process.
Check out Richie’s project on GitHub.
Despite the development of AlwaysOn in recent releases of SQL Server, log shipping is still a great way to set up a copy of databases to be used for reporting. One of the main reasons it is great is because, unlike AlwaysOn, it is available in less expensive editions like Standard and Web from SQL Server 2008 onwards. Sure, in 2016 AlwaysOn will be available in Standard, but in a greatly deprecated form, and you cannot read from the secondary. So it will be good for DR, but not for reporting (as an aside it still might be easier to set up log shipping for DR than AlwaysOn Basic because you need to setup a failover cluster. Read through the “how to set up Standard Edition Availability Groups” here.) However you do need to be careful though when setting up log shipping across different editions of SQL Server: whilst you can log ship between Enterprise to Standard/Web, if the database uses any Enterprise features then you’ll need to log ship to an Enterprise edition of SQL Server. And because you’ll be using the database for reporting, you’ll need to get it licensed.
Log shipping is a venerable disaster recovery technique and it behooves database administrators to know of its existence.