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Category: Administration

Oracle: RMAN and Non-Synchronizing Standby Database

Published 2023-09-22 by Kevin Feasel

David Fitzjarrell proffers advice on recovering from a non-synchronizing standby database:

Occasionally the unthinkable can occur and the DBA can be left with a standby database that is no longer synchronizing with the primary. A plethora of “advice”will soon follow that discovery, most of it much like this:

“Well, ya gotta rebuild it.”

Of course the question to ask is “how far out of synch is the standby>” That question is key in determining how to attack this situation. Let’s go through the two most common occurrences of this and see how to address them.

Read on to see David’s advice.

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Service Level Agreements (RPO and RTO) and SQL Server

Published 2023-09-18 by Kevin Feasel

David Klee wants to know how much downtime is acceptable to you:

Database professionals of the world – I have a question. Has your organization defined service level agreements (SLAs) for your data estate? I’m talking specifically the Recovery Point Objective (RPO) and Recovery Time Objective (RTO), and to have these defined not in an arbitrary number of nines, but in minutes or hours. If these aren’t defined from above, your business continuity plan is doomed to fail.

Read on to learn what RPO and RTO mean, how to think in terms of RPO and RTO, and some of David’s recommendations.

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Don’t Try These with SQL MI and Private Endpoints

Published 2023-09-08 by Kevin Feasel

Zoran Rilak wraps up a series on Azure SQL Managed Instance and its support for private endpoints:

The first two installments of this mini-series discussed a couple of basic and advanced scenarios involving private endpoints. Today we’ll look at some ways private endpoints cannot be used to implement scenarios where one might expect otherwise.

Read on for four of these in total, laying out things you cannot do via private endpoint to a SQL Managed Instance. In fairness, Zoran also provides what I would consider reasonable work-arounds for each of those: have a VM jumpbox in the same virtual network for DAC connections, peer your virtual networks for replication, and so on.

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Troubleshooting a Downed SQL Server

Published 2023-09-07 by Kevin Feasel

Kevin Hill takes us through an issue:

This is a stand-alone bare metal server located at a hosting facility with some local storage as well as NAS storage.  SQL Server 2016 Standard Edition, 8 cores, 128GB RAM.  The primary database is nearing 1TB and is has multiple filegroups (Active, Archive, Indexes, etc.).   This database and apps that touch it ARE the company.

Read on for Kevin’s process, which was a solid bit of troubleshooting.

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Transaction Log Files and Instant File Initialization

Published 2023-09-07 by Kevin Feasel

Erik Darling preps us for SQL Server 2022:

Look, I don’t blame you if you haven’t dug deep into what SQL Server 2022 has to offer just yet. It’s hard enough to keep up with all the problems fixed and caused by cumulative updates.

One thing you may want to pay attention to is how transaction log files are grown and VLFs are created, especially for new databases.

Read on to see what has changed there.

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Monitoring Azure SQL Transaction Log Usage with Powershell

Published 2023-09-05 by Kevin Feasel

Jose Manuel Jurado Diaz has a script for us:

Database administrators and IT professionals often need to be proactive in monitoring resources, especially when working in cloud environments like Azure SQL. One critical resource that requires monitoring is the transaction log of a SQL Server database. If it fills up, it can hinder database operations, leading to potential application downtime.

In this article, we’ll discuss a PowerShell script that monitors transaction log usage in Azure SQL databases and sends an email alert if a database exceeds a specific threshold.

There is a reference in the script to Check-LogUsage, which appears to be a different function, likely related to the linked T-SQL statement Jose posted.

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Australian Azure Downtime After-Action Report

Published 2023-09-05 by Kevin Feasel

Brent Ozar shares some thoughts:

Note that 11:34, the decision was made to shut down infrastructure without Microsoft failing your databases over elsewhere. If you were an Azure SQL DB or Cosmos DB user, and you weren’t paying for replicas in another data center, it was up to you to follow Microsoft’s disaster recovery guidance.

Controversial opinion: I actually love that and I think it’s great.

That is definitely a controversial opinion, but it’s also one I agree with. Read on for more of Brent’s thoughts.

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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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Group Replication in MySQL

Published 2023-08-29 by Kevin Feasel

Aisha Bukar continues a series on replication in MySQL:

MySQL Group replication is a remarkable feature introduced in MySQL 5.7 as a plugin. This technology allows you to create a reliable group of database servers. One of the most important features of MySQL’s group replication is that it allows these servers to store redundant data. This allows the database state to be replicated across multiple servers making it efficient in the situation where there is a server breakdown, the other servers in the cluster can agree to work together.

This technology is built on top of the MySQL InnoDB storage engine and employs a multi-source replication approach which we discussed in part 3 of the replication series. In this article, we’d be looking at an overview of the group replication technique, configuring and managing group replication, and also best practices for group replication. So, let’s get started!

Read on to see how it works and some recommendations around using it.

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Advanced Scenarios for Private Endpoints to Azure SQL MI

Published 2023-08-25 by Kevin Feasel

Zoran Rilak digs in:

In the previous installment of this mini-series, we covered basic scenarios involving private endpoints. If you aren’t familiar with private endpoints and Private Link in general, it might be a good idea to quickly review them to get the feel of how they apply when Azure SQL Managed Instance is in the mix.

In this article, we’ll dive into more involved scenarios that build on those from last week:

5. Hub and spoke topology

6. Partner or ISV giving access to their customers

7. Two SQLs talking to each other: linked server, transactional replication

8. Failover group listener using private endpoints

Read on for architecture diagrams and descriptions for each of these scenarios.

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