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Category: Administration

Port Scanning for SQL Server

Published 2023-09-27 by Kevin Feasel

David Fowler performs one of the early steps of a penetration test:

Since witnessing a rather nasty cyber attack around a year ago, I’ve been thinking quite a bit about security. Do we really know how secure our SQL Servers are? Penetration testing is a great way to find out where our weaknesses and vulnerabilities are. Ideally you probably want to be getting regular pen tests conducted by external companies (although in my experience, some are better than others. I’ve known some who argue totally pointless issues and miss glaring holes which I know exist, but that’s a whole different story) but wouldn’t it be useful if we could conduct some of these tests ourselves?

In this series of posts, I’m going to try to knock together a little pen testing toolbox so that we can hopefully find some of these vulnerabilities. I’m no pen testing expert and this is never going to replace getting a professional pen tester in to test your setup but it might go some way to helping us understand some of our vulnerabilities and identify them.

Click through to see what David did, as well as an alert which helped pick out this port scanning operation.

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Upgrading SQL Server Cloud VMs

Published 2023-09-27 by Kevin Feasel

Brent Ozar recommends you check your cloud provider’s VM listings:

If you’ve been in Azure or Amazon for a few years, you’re probably on old, slow hardware.

In the last 3 weeks, I’ve had two clients who’d both been early cloud adopters. When they’d migrated to the cloud, they both used Azure Ev3 VMs – at the time, a good choice for SQL Server due to its relatively high amount of memory. When the Ev3 VM types were announced in 2017, they were hosted on Intel Broadwell and Haswell processors with 2.3-2.4GHz processing speed.

Also, even if you’re locked into a 1-year or 3-year deal, I know that at least Azure is usually willing to switch your VM class registration if you contact your support person. I’m not positive if AWS does the same but it wouldn’t shock me.

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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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