How scheduler and script stand in supporting failover (Percona and Marco example) 

In part one of this series,  I had illustrated how simple scenarios may fail or have problems when using Galera native support inside ProxySQL. In this post, I will repeat the same tests but using the scheduler option and the external script.

The Scheduler

First a brief explanation about the scheduler.

The scheduler inside ProxySQL was created to allow administrators to extend ProxySQL capabilities. The scheduler gives the option to add any kind of script or application and run it at the specified interval of time. The scheduler was also the initial first way we had to deal with Galera/Percona XtraDB Cluster (PXC) node management in case of issues. 

…

How native ProxySQL stands in failover support (both v2.0.15 and v2.1.0)

In recent times I have been designing several solutions focused on High Availability and Disaster Recovery. Some of them using Percona Server for MySQL with group replication, some using Percona XtraDB Cluster (PXC). What many of them had in common was the use of ProxySQL for the connection layer. This is because I consider the use of a layer 7 Proxy preferable, given the possible advantages provided in ReadWrite split and SQL filtering. 

The other positive aspect provided by ProxySQL, at least for Group Replication, is the native support which allows us to have a very quick resolution of possible node failures.

ProxySQL has Galera …

Kubernetes operators are meant to simplify the deployment and management of applications. Our Percona Kubernetes Operator for Percona XtraDB Cluster serves the purpose, but also provides users the flexibility to fine-tune their MySQL and proxy services configuration.

The document Changing MySQL Options describes how to provide custom

my.cnf

configuration to the operator. But what would happen if you made a mistake and specified the wrong parameter in the configuration?

Apply Configuration

I already deployed my Percona XtraDB Cluster and deliberately submitted the wrong

my.cnf

  configuration in

cr.yaml

 :

spec:
...
  pxc:
    configuration: | …

Kubernetes has been a big trend for a while now, particularly well-suited for microservices. Running your main databases on Kubernetes is probably NOT what you are looking for. However, there’s a niche market for them. My colleague Stephen Thorn did a great job explaining this in The Criticality of a Kubernetes Operator for Databases. If you are considering running your database on Kubernetes, have a look at it first. And, if after reading it you start wondering how the Operator works, Stephen also wrote an Introduction to Percona Kubernetes Operator for Percona XtraDB Cluster (PXC), which presents the Kubernetes architecture and how the Percona Operator simplifies the deployment of a …

Our recent survey showed that many organizations saw unexpected growth around cloud and data. Unexpected bills can become a big problem, especially in such uncertain times. This blog post talks about how Kubernetes scaling capabilities work with Percona Kubernetes Operator for Percona XtraDB Cluster (PXC Operator) and can help you to control the bill.

Resources

Kubernetes is a container orchestrator and on top of it, it has great scaling capabilities. Scaling can help you to utilize your cluster better and do not waste money on excessive capacity. But before scaling we need to understand what capacity is and how Kubernetes manages CPU and memory resources.

There are two resource concepts that you should be aware of: …

In my talk on Percona Live (download the presentation), I spoke about how we can use Percona Kubernetes Operators to deploy our own Database-as-Service, based on fully OpenSource components and independent from any particular cloud provider.

Today I want to mention an important tool that I use to test our Operators: ChaosMesh, which actually is part of CNCF and recently became GA version 1.0.

ChaosMesh seeks to deploy chaos engineering experiments in Kubernetes deployments which allows it to test how deployment is resilient against different kinds of failures.

Obviously, this tool is important for Kubernetes Database …

Kata containers are containers that use hardware virtualization technologies for workload isolation almost without performance penalties. Top use cases are untrusted workloads and tenant isolation (for example in a shared Kubernetes cluster). This blog post describes how to run Percona Kubernetes Operator for Percona XtraDB Cluster (PXC Operator) using Kata containers.

Prepare Your Kubernetes Cluster

Setting up Kata containers and Kubernetes is well documented in the official github repo (cri-o, …

So you’ve just added some more memory to your MySQL server; now what? If you’ve been around the MySQL block for a while, you know that nothing is automatically changed to take advantage of this new system RAM. Let’s have a look at a few parameters you would want to adjust.

InnoDB Parameters innodb_buffer_pool_size

The InnoDB buffer pool is “…the memory area that holds cached InnoDB data for both tables and indexes.” This parameter is probably the #1 tuning parameter in MySQL. If your buffer pool is too small, then InnoDB must spend extra CPU/Disk time, loading, and unloading pages in/out of memory. This is time better spent executing your queries.

The default size of this cache is 128MB; woefully small for any serious database. Increasing the size of this cache allows more frequently accessed pages to remain in memory for the fastest access. Obviously, you do not need a buffer pool which is larger than your …

Understanding how MySQL uses memory is key to tuning it for optimal performance as well as troubleshooting cases of unexpected memory usage, i.e. when you have MySQL Server using a lot more than you would expect based on your configuration settings.

Early in MySQL history, understanding memory usage details was hard and included a lot of guesswork.  Is it possible that some queries running require a large temporary table or allocated a lot of memory for stored user variables?  Are any stored procedures taking an unexpectedly high amount of memory? All could be reasons for excessive MySQL memory usage, but you would not easily see if that is just the case.

All that changed with MySQL 5.7, which added memory instrumentation in Performance Schema, and with MySQL 8.0, this instrumentation is enabled by default, so you can get this data from pretty much any running instance.

If you’re looking for current memory …

Galera replication technology, a key component of Percona XtraDB Cluster, suffered from a remote code execution vulnerability. Percona has been working with the vendor since early September on this issue and has made releases available to address the problem.

Applicability

A malicious party with access to the WSREP service port (4567/TCP) as well as prerequisite knowledge of the configuration of the Galera cluster name is required in order to exploit this vulnerability, which leads to remote code execution via the WSREP protocol. 

Fixes are available in Percona XtraDB Cluster versions:

>= 8.0.20-11.2

>= …