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Category: Backups

The Internals of Backup Compression

Published 2023-10-10 by Kevin Feasel

Andy Yun continues a series on how backups work in SQL Server:

Welcome back to Part 4 of my Backup Internals series. Today, I’d like to spend a little time exploring backup compression.

When you take a regular FULL BACKUP, SQL Server is literally taking a byte-for-byte copy of your data files. Don’t believe me? Then go read this, then come back. Additionally, Microsoft architected BACKUP operations such that the resource utilization and impact would be minimal (when using default parameters).

This post taught me a few things about the practical impact of enabling compression. Even after reading this, however, I would almost always enable it for two reasons. First, storage is usually the bottleneck for organizations, so actions which reduce storage utilization can improve overall performance. Second, there are limits to how much we can store, so compressing backups may let me get away with holding more backups on a given LUN or drive.

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Verifying a Backup in SQL Server

Published 2023-09-20 by Kevin Feasel

Chad Callihan knows your last backup is only as good as your last restore:

Is the process of testing your backups something you know you should do but never get around to? Do you find yourself assuming all is well with backups while putting out other fires? Test-DbaLastBackup, part of the beloved dbatools, can solve your dilemma.

There are many options available when using Test-DbaLastBackup. Let’s explore a few of these options and see some examples of how to use them.

Click through to learn more about this. And you could easily put together Powershell scripts to stagger your restorations over a time frame (such as, 15% of your databases each day, so that you get to 100% by the end of the week).

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Restoring Backups from S3 to Azure SQL MI

Published 2023-09-06 by Kevin Feasel

Strahinja Rodic announces a new feature going to GA:

In September last year SQL server 2022 introduced new feature – backup and restore to simple storage service (S3) – compatible object storage that grants the user the capability to back up or restore their databases using S3-compatible object storage, whether that be on-premises, or in the cloud.

To provide this integration Azure SQL MI is enriched with a new S3 connector, which uses the S3 REST API to connect to Amazon S3 storage. It extends the existing RESTORE FROM URL syntax by adding support for the new S3 connector using the REST API.

Click through to see what you need to have set up for it to work, as well as the restoration process.

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Restoring a Database with Standby in SQL Server

Published 2023-08-31 by Kevin Feasel

Steve Jones stands by for station identification:

Sometimes you want to restore part of your data, but you still want the option to continue restores. A classic example of this is when you are restoring a number of transaction logs and want to check the data to find a place where certain values haven’t been changed.

Suppose someone deletes a bunch of data between 10am and 11am from the supplier table. You know that they added “Acme” to this table before the delete. You might restore up to 10am and check the supplier table for the old data and look for Acme. If it’s not there, maybe you restore the 10:05am log backup and check again. If it’s not there, then the 10:10am log, etc.

Click through to see how you can do that.

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CPU Threads in SQL Server Backups

Published 2023-08-25 by Kevin Feasel

Andy Yun dives in:

Welcome back to Part 3 of my SQL Server Backup Internals Series.

In Part 1, I introduced the “parts” of a BACKUP Operation and in Part 2, we delved into Backup Buffers. Today, we’re going to talk about what manipulates those Backup Buffers = CPU Threads. This’ll be a longer blog, so go refill your coffee now.

Andy did an outstanding job explaining what reader and writer threads do and how SQL Server picks the numbers of each.

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Restoring SSAS Cubes to SQL Server 2022 CU5

Published 2023-08-21 by Kevin Feasel

Meagan Longoria runs into a problem:

I have a client who was upgrading some servers from pre-2022 versions of SQL Server to SQL Server 2022 CU7. They had some multidimensional SSAS cubes that were to go on the new server. But they ran into an issue after the upgrade. After restoring a backup of an SSAS database to the new server they found that they could no longer modify the data source using SSMS.

Read on to see what the problem was, as well as how to fix it.

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Backup Buffers in SQL Server

Published 2023-07-27 by Kevin Feasel

Andy Yun continues a series on backup internals:

Welcome to Part 2 of SQL Server Backup Internals. This blog series is a companion piece to my How to Accelerate Your Database Backups for MSSQLTips.com. In Part 1 of this blog series, I introduced the parts of a BACKUP operation.

Now let’s start focusing on performance characteristics. We can impact the performance of a BACKUP operation by making changes to or more of the following:

Click through for that list, as well as an extended analogy on buffer count and max transfer size.

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Testing a Database Restoration

Published 2023-07-26 by Kevin Feasel

Kevin Hill fixes a problem:

Pain Point: Something bad happened and you need to restore a SQL Server database.

Pain Point you didn’t know you had: The backup files are all corrupt due a problem with the storage subsystem.

A backup is only as good as the last time you tested its restoration. Kevin shows just how easy it is to perform this test using DBATools.

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Physical Backups in Postgres via pg_basebackup

Published 2023-07-05 by Kevin Feasel

Muhammad Ali takes a backup:

The security and integrity of your company’s data are crucial in today’s data-driven environment. You must have a reliable backup plan in place to protect your PostgreSQL databases against unplanned calamities. In this article, we’ll examine how to create physical backups using the PostgreSQL tool pg_basebackup. We’ll talk about client needs, business use cases, backup space complexity, disaster recovery, point-in-time recovery (PITR), and how to use PostgreSQL to put these strategies into practice.

Read on for the instructions. Of particular importance is that point-in-time recovery.

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