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Category: Backups

Alerting On Missed Log Backups

Published 2018-08-07 by Kevin Feasel

Jamie Wick shows us how to build out an alert if we’ve exceeded a threshold for time since the last log backup:

The primary reason most transaction logs start to (unexpectedly) grow is that the transaction log hasn’t been backed up. This is usually caused by one of two situations: the log backup job failed, or the log backup job didn’t start. Most options for backing up SQL transaction logs (3rd party software, SQL Agent job, or maintenance plan) will include an alert/notification mechanism for when the job fails. Where some backup options are lacking is in notifying that a (log) backup that should have been taken, wasn’t. If the backup (or management) software doesn’t include an alert for missing backups, SQL Server (2008 & newer) has a solution. Policy Based Management (PBM) includes a policy (Last Log Backup Date) that will send an email notification when the last backup date/time exceeds a specified threshold.

A good use for a woefully underappreciated tool.

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Azure SQL Data Warehouse Restore Points

Published 2018-08-07 by Kevin Feasel

Arun Sirpal explains how backups work with Azure SQL Data Warehouse:

The question is how are backups done with Azure SQL DW?

It is very different from Azure SQL DB (which you would expect). Azure SQL DW has a totally different architecture to its classic database counter-part. Restore points are the key here. Automatic ones are taken throughout the day and are kept for seven days only. Worst case scenario is the time between the restore points will be eight hours hence giving an eight hour RPO (Recovery Point Objective).

You can also create manual restore points, as Arun shows.

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It’s 10 O’Clock; Do You Know Where Your Backups Are?

Published 2018-07-26 by Kevin Feasel

Adrian Buckman has a script which makes sure your backups are where msdb says they are:

Here is the information that the script provides:

  1. Warn of restores over the top of the database since its last FULL backup

  2. Show database snapshots currently against the database

  3. Show the last FULL, DIFF and LOG backup for the database including the backup durations and backup age.

  4. Backup file information such as backup start/finish time , file path , first LSN , Last LSN , a status column which states whether the log chain is in tact based on First and last LSN but also if the file exists on disk, and finally a file exists column which will tell you if the file still exists on disk.

This is a great script if you take transaction log backups frequently (typically a good idea).

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SQL Server Backup Restoration With LOADHISTORY

Published 2018-07-20 by Kevin Feasel

Kenneth Fisher explains what the LOADHISTORY option means when you run a RESTORE VERIFYONLY command:

So, first of all, it only works with RESTORE VERIFYONLY. RESTORE VERIFYONLY does some basic checking on a backup to make sure that it can be read and understood by SQL. Please note, it does not mean that the backup can be restored. It will check things like the checksum, available diskspace (if you specify a location), the header and that the backup set is actually complete and readable. Basically enough to see if it will start restoring, but it could still have errors later on.

As for what LOADHISTORY actually does? It causes you to write an entry to the restore history table. You can tell which record this is because the restore_type is set to a V. Really, the only benefit here (as I see it) is that you can do reporting on what backups you’ve verified.

Click through for a demo.

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Cross-Server Database Restoration With Minion Backup

Published 2018-07-02 by Kevin Feasel

Jen McCown walks us through how to restore a database on a different server with Minion Backup:

Today we’ll look at configuring a common, repeatable scenario: take the latest backup of MyDB from ProdServer1 and restore it to DevServer1. There are four basic steps to the setup and execution:

  1. Configure Minion Backup and let it run on ProdServer1.Restoring with MB requires at least one full backup taken by MB. (Note that you don’t need Minion Backup on DevServer1 for this scenario.)

  2. Configure restore settings paths. You know how sometimes a restore requires one or more “WITH MOVE” clauses?  Configure this once for your source-target pair, and MB takes care of it from then on.

  3. Configure the restore tuning settings (optional). Oh yes, we tune our backups AND our restores!

  4. Generate and run the restore statements.

It’s a good walkthrough if you’re a Minion Backup user.  If you’re not and you’re not particularly happy with your backup solution, I recommend giving it a try.

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Backing Up Azure Data Lake Store Data

Published 2018-06-29 by Kevin Feasel

Hugo Almeida has some hints for backing up Azure Data Lake Store data using Azure Data Factory:

Our Hadoop HDP IaaS cluster on Azure uses Azure Data Lake Store (ADLS) for data repository and accesses it through an applicational user created on Azure Active Directory (AAD). Check this tutorial if you want to connect your own Hadoop to ADLS.

Our ADLS is getting bigger and we’re working on a backup strategy for it. ADLS provides locally-redundant storage (LRS), however, this does not prevent our application from corrupting data or accidentally deleting it. Since Microsoft hasn’t published a new version of ADLS with a clone feature we had to find a way to backup all the data stored in our data lake.

We’re going to show you How to do a full ADLS backup with Azure Data Factory (ADF). ADF does not preserve permissions. However, our Hadoop client can only access the AzureDataLakeStoreFilesystem (adl) through hive with a “hive” user and we can generate these permissions before the backup.

Read the whole thing if you’re thinking of using Azure Data Lake Store.

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Backing Up SQL Server To S3

Published 2018-06-19 by Kevin Feasel

David Fowler shows how to back up SQL Server directly to an AWS S3 bucket:

I’ve been having a little play around with AWS recently and was looking at S3 (AWS’ cloud storage) when I thought to myself, I wonder if it’s possible to backup up an on premise SQL Server database directly to S3?

When we want to backup directly to Azure, we can use the ‘TO URL’ clause in our backup statement.  Although S3 buckets can also be accessed via a URL, I couldn’t find a way to backup directly to that URL.  Most of the solutions on the web have you backing up your databases locally and then a second step of the job uses Power Shell to copy those backups up to your S3 buckets.  I didn’t really want to do it that way, I want to backup directly to S3 with no middle steps.  We like to keep things as simple as possible here at SQL Undercover, the more moving parts you’ve got, the more chance for things to go wrong.

So I needed a way for SQL Server to be able to directly access my buckets.  I started to wonder if it’s possible to map a bucket as a network drive.  A little hunting around and I came across this lovely tool, TNTDrive.  TNTDrive will let us do exactly that and with the bucket mapped as a local drive, it was simply a case of running the backup to that local drive.

Quite useful if your servers are in a disk crunch.  In general, I’d probably lean toward keeping on-disk backups and creating a job to migrate those backups to S3.

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Why Your Transaction Log Is Full: LOG_BACKUP

Published 2018-06-18 by Kevin Feasel

Jen McCown explains why you might get the error message “The transaction log for database ‘<your database>’ is full due to ‘LOG_BACKUP'”:

Your transaction log is full. Both Microsoft, and about 100 articles and blogs have covered this topic, but let’s take a quick look anyway. Because, you know, it comes up all the time.

Summary:

  1. This error message points to a lack of log backups.

  2. Make sure using sys.databases.

  3. Start backing up the log.

  4. You can shrink the log if necessary.

  5. A note on SIMPLE mode, and why it’s often a terrible idea.

This is a good summary of the problem and various solutions.

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User-Defined Restore Points In Azure SQL DW

Published 2018-06-15 by Kevin Feasel

Kevin Ngo announces a new feature in Azure SQL Data Warehouse:

Previously, SQL DW supported only automated snapshots guaranteeing an eight-hour recovery point objective (RPO). While this snapshot policy provided high levels of protection, customers asked for more control over restore points to enable more efficient data warehouse management capabilities leading to quicker times of recovery in the event of any workload interruptions or user errors.

Now, with user-defined restore points, in addition to the automated snapshots, you can initiate snapshots before and after significant operations on your data warehouse. With more granular restore points, you ensure that each restore point is logically consistent and limit the impact and reduce recovery time of restoring the data warehouse should this be needed. User-defined restore points can also be labeled so they are easy to identify afterwards.

Creating a user-defined restore point is a one-liner in Powershell, and it’s something you could do after each warehouse load, for example.

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Restoring Point-In-Time To Another Azure SQL Managed Instance

Published 2018-06-08 by Kevin Feasel

Jovan Popovic announces an improvement to Azure SQL Database Managed Instances:

Azure SQL Database Managed Instance enables you to create a database as a copy of another database at some point in time in the past. This is known as point-in-time restore feature, and up till now you could perform point-in-time restore only within the same instance.

The latest release of Azure SQL Database Managed Instance enables you to perform point-in-time restore of a database from one instance to another. This might be useful if you need to be sure that you could easily restore a database to another instance if there is some issue on the original instance, or if you need a database for testing or auditing purposes on the test instance and you want to use copy of some of the existing database on another server.

Click through for the current requirements and limitations, as well as a sample.

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