Press "Enter" to skip to content

Category: Linux

Persistent Memory for SQL Server on Linux

The SQL Server team shows how you can configure persistent memory for SQL Server on Linux:

With the release of SQL Server 2019 on Linux, Microsoft introduced persistent memory (PMEM) support on Linux. This is an exciting development, as previous versions of SQL Server on Linux didn’t support PMEM. Let’s look at how to configure the PMEM for SQL Server on Linux.

SQL Server 2016 introduced support for non-volatile DIMMs and an optimization called Tail of the Log Caching on NVDIMM. These leveraged Windows Server direct access to a persistent memory device in DAX mode to reduce the number of operations needed to harden a log buffer to persistent storage.

SQL Server 2019 extends the support for PMEM devices to Linux, providing full enlightenment of data and transaction logs placed on PMEM. Enlightenment is a way to access the storage device using efficient user-space memcpy() operations. Rather than going through the file system and storage stack, SQL Server leverages DAX support on Linux to place data directly into the device. This helps to reduce latency.

Click through for the configuration steps.

Leave a Comment

When mssql-cli Installation Fails on Ubuntu

Kellyn Pot’vin-Gorman shares a slew of reasons why mssql-cli might fail to install:

The easiest scenario for many to deploy SQL Server 2019 on Linux to start working with it, is most likely an Ubuntu distribution, (flavor) of Linux.  With that, you may want to play with the newest tool for command line execution of SQL, which isn’t sqlcmd, but mssql-cli.  It’s got some awesome new features, which I won’t go into here, but focus on installation failures instead, which happens not because the installation is complicated but because of the demands still for Python 2.7 when 3+ versions are required for newer software.

mssql-cli requires Python 3, so I recommend checking the version before running the mssql-cli installation command, as this may save you a lot of work with dependencies.  I’ll still go through the steps to if you want to force it to work with Python 2.7, but seriously, just using the right version of Python will make it so much easier.

Read on for just shy of a dozen different failure modes.

Leave a Comment

Changing Colors in Bash

Kellyn Pot’vin-Gorman shows how you can change the colors you see in bash shells:

I agree with him-  you never know what the projector quality will be, the lighting in the room, color-blind attendees or other factors that could impact the readability of  the demonstration when you have a black background and colored text.  I realized, as the Azure Cloud Shell is a service, we have less control of the terminal offered to us, so it was important to tell people how to update their Azure Cloud Shell to change the execution prompt to not be in color and highlight the background in white, with black text bolded for easier reading.

Click through for a sample .bashrc file as well as a bonus “How do I exit vim?” bit. The correct answer is, you never exit vim; you simply dedicate the rest of your life to it.

Comments closed

Configuring Memory Limits for SQL Server in Kubernetes

Anthony Nocentino doesn’t have all the RAM in the world:

With that Pod deployed, I loaded up a HammerDB TPC-C test with about 10GB of data and drove a workload against our SQL Server. Then while monitoring the workload…boom HammerDB throws connection errors and crashes. Let’s look at why.

First thing’s first, let’s check the Pods status with kubectl get pods. We’ll that’s interesting I have 13 Pods. 1 has a Status of Running and the remainder have are Evicted. 

Anthony does a great job of explaining the problem and showing you the solution.

Comments closed

Non-Root SQL Server 2019 Containers

Vin Yu announces a change to Microsoft’s container configuration for SQL Server 2019:

The application process within most Docker containers is running as a root user meaning the process has root privileges within the container user space. The root user within the container is also the same root (uid 0) on the host machine, and if the user can break out of the container, they would have root permissions on the host. Running as root is convenient for development, testing and CI/CD use cases but for production use cases, it is safest to run SQL Server as a non-root process within the container. In this blog, we’re going to share with you how you can preview this upcoming improvement by creating your own non-root SQL Server container.

Vin has a quick demonstration of how it works.

Comments closed

strace and SQL Server Containers

Anthony Nocentino tries using strace to diagnose SQL Server process activity in a container:

We’re attaching to an already running docker container running SQL. But what we get is an idle SQL Server process this is great if we have a running workload we want to analyze but my goal for all of this is to see how SQL Server starts up and this isn’t going to cut it.
 
My next attempt was to stop the sql19 container and quickly start the strace container but the strace container still missed events at the startup of the sql19 container. So I needed a better way.

Don’t worry—Anthony finds a better way.

Comments closed

CPU Usage DMV in SQL Server on Linux

Tejas Shah announces an improvement to sys.dm_os_ring_buffers in SQL Server 2019 RC1 on Linux:

Sys.dm_os_ring_buffers DMV has been a key DMV used for monitoring SQL Server by built-in tools as well as third party monitoring utilities. When SQL Server 2017 was released on Linux, unfortunately this DMV did not return correct CPU usage information by SQL Server process. SQL Server team is glad to announce that the starting with SQL Server 2019 release candidate, the sys.dm_os_ring_buffers DMV returns SQL CPU utilization correctly. This improvement should benefit the SQL Server monitoring ecosystem on Linux by providing a way to monitor SQL Server CPU usage and enable decision making to engage corrective action if required.

This brings it in line with what we have on Windows.

Comments closed

Merge Replication on Linux

Jignesh Raiyani shows how you can set up merge replication on SQL Server on Linux:

In this article, we will discuss to deploy SQL Server Merge Replication on Linux environment. Many SQL Server features are not available on Linux by Microsoft but the Replication feature exists for Linux Environment Edition. Before starting anything, let’s address this question – what is Merge Replication?

Merge Replication is a data synchronization process with one database (Publisher) to other databases (Subscriber) and vice versa. The data synchronization audit will be controlled by the distributor (Distribution database). The distributor database will manage the data synchronization between Publisher and Subscribers.

Merge replication is also an unending nightmare of pain, but you do what you gotta do.

Comments closed

Supported Distributions for SQL Server on Linux

Kevin Chant looks at each of the supported distributions for installing SQL Server on Linux:

Another key point is that even though SQL Server on Linux is supported on various distributions SQL Server can be installed on other distributions instead.

Although I would only advise this for testing purposes only because SQL Server would not be supported by Microsoft on these other distributions.

In reality, you can probably install SQL Server on more diverse distributions than the ones listed. However, I have focused on the main ones below.

As Kevin points out, there’s a difference between “working” and “supported.” If you’re futzing about with a dev database or trying to learn the platform, go ahead and install it on Elementary or some other unsupported distro. But if you have a production issue, the fact that you installed SQL Server on an ancient version of Slackware may win you plaudits but won’t get you support.

Comments closed