SQL Server

Update for T-SQL Tuesday #84

Well, this year I was challenged with the goal of speaking publicly three times, well I blew that out of the water and have spoken 8 times (one of which was a major IT conference) this year with one more on deck for Friday at the Albuquerque SQL Server User Group. I never thought it would have gone this far, but it certainly is fun and exciting. I encourage you to set a goal, even if it’s speaking only one time…set the goal and do it! You’ll be surprised where it takes you, the great people you meet along the way and the support those same folks give you!

What I’ve noticed this year is that there’s really not another group of people like the SQL Community.  Earlier this year Paul Randal ( b | t ), in the name of community, offered his services to mentor to a small group of people. Check it out here. Crazy as it may sound he went ahead and offered mentoring to everyone that submitted here and I was on that list. Here’s my blog post submission

In our final post in our “Load Testing Your Storage Subsystem with Diskspd” series, we’re going to look at output from Diskspd and run some tests and interpret results. In our first post we showed how performance can vary based on access pattern and IO size. In our second post we showed how to design a test to highlight those performance characteristics and in this post we’ll execute those tests and review the results.  First let’s walk through the output from Diskspd, for now don’t focus on the actual results.

In this post we’re going discuss how to implement load testing of your storage subsystem with DiskSpd. We’re going to craft tests to measure bandwidth and latency for specific access patterns and IO sizes. In the last post “Load Testing Your Storage Subsystem with Diskspd”  we looked closely at access patterns and I/O size and discussed the impact each has on key performance attributes.

Diskspd command options

Let’s start with some common command options, don’t get caught up on the syntax. Diskspd’s documentation is fantastic. It’s included with the program download here. Here I’m going to tell you why I set these settings this way, so you can adjust them as needed for your environments.

Encrypting Connections To SQL Server Using Certificates

In this post we’re going to cover configuring a connection string in.NET applications for encrypting connections to SQL Server using certificates. The audience for this document is a developer that needs to configure encrypted connections from applications to a database server.

Encrypting connections with SQL Server using Certificates consists of two parts:

• An appropriately configured connection string
• A server certificate installed on the Database Engine (not covered in this post)

Configuring a Connection String

One of the primary activities I do before bringing SQL Server into production is load testing the storage subsystem. On a new system this is critical because I want to ensure that we’re “getting what we’ve paid for” when it comes to the disk subsystem. All too often there’s a configuration issue, component mismatch, a fundamental misunderstanding of the technology or worse an insufficient disk subsystem…these all can lead to poor disk performance. Even if it’s the simplest test, its imperative to measure performance as it’s significantly harder to make changes to a SQL Server once a database is in production. So do your testing. This is especially an important topic if your disks are not direct attached or in a shared storage environment such as a SAN or VMware data store. Storage networks, controllers, shelves…it gets complicated fast!

In previous posts here and here we discussed AlwaysOn Availability Group replication latency and monitoring concepts, specifically the importance of monitoring the send_queue and redo_queue. In this post I’m going to show you a technique for monitoring Availability Group replication latency with Redgate SQL Monitor and its Custom Metric functionality.

Here’s the rub, monitoring AGs is a little interesting for the following reasons

1. We’re interested in trending and monitoring and that isn’t built into SQL Server or SSMS’s AlwaysOn Dashboard.  Both provide only point in time values.
2. We’ll need to monitor the health of the Availability Group as a whole. So we want to track performance data on all replicas in the AG. But interestingly the redo queue and send queue values in the DMVs on the primary are always NULL. So we need to get those values from the secondary replicas.
3. Further, to work this into SQL Monitor’s Custom Metric framework we’ll need to limit our query’s result set to a single row and value.

Redo Queue

The redo queue is the amount of log records that haven’t been sent to a secondary replica in an AG. We want to track this as it is a measure of the amount of data on a secondary that is not yet redone into the database and can impact operations offloaded to secondaries

Its pretty often that you have to sit down at a SQL Server and need sort out what the backup situation is. One of the first things that I check is, when did the last backup for each database complete? But answering that question is getting more complicated. If you’re using Availability Groups, you could be offloading your backups to a secondary and that can skew your backup data.  In Availability Groups, database backup history is only stored on the instance that the backup executed on.

Over the last two years I have had the pleasure of attending all three SQLskills Immersion Event classes. This training is second to none in its quality and intensity. The three courses help you look at SQL Server from different angles and are major parts of my job and likely yours as well. Each course uses a building block approach where you’re introduced into core fundamentals that the later modules build upon with more advanced topics.

In this post we are going to show the implementation of a PowerShell script using SMO to move data between filegroups on SQL Server. This article is the second of our two part series on “Moving SQL Server data between filegroups – Database Structures”, you can find the first article here.

The Challenge

Looking around on the web, I couldn’t find a solution to the problem of moving data between filegroups that I liked. Further, many of those solutions are T-SQL based, which I thought were very complex. So I went off to write it myself. The problem lends itself to an iterative solution and I felt that T-SQL was not the right tool for the job. Enter PowerShell, which give us the ability to easily iterate over sets of data with minimal code, couple that with the SQL Server Management Object model and we have the makings of an elegant solution.