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Displaying posts with tag: proxy (reset)
Mastering Continuent Clustering Series: Converting a standalone cluster to a Composite Primary/DR topology using INI configuration

In this blog post, we demonstrate how to convert a single standalone cluster into a Composite Primary/DR topology running in two data centers.

Our example starting cluster has 5 nodes (1 master and 4 slaves) and uses service name alpha. Our target cluster will have 6 nodes (3 per cluster) in 2 member clusters alpha_east and alpha_west in composite service alpha.

This means that we will reuse the existing service name alpha as the name of the new composite service, and create two new service names, one for each cluster (alpha_east and alpha_west).

Below is an INI file extract example for our starting standalone cluster with 5 nodes:

[defaults]
...

[alpha]
connectors=db1,db2,db3,db4,db5
master=db1
members=db1,db2,db3,db4,db5
topology=clustered

To convert the above configuration to a Composite Primary/DR:

  1. First you must stop all services on all existing nodes:
    shell> stopall …
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Mastering Continuent Clustering Series: Tungsten and SELinux, a Case Study

In this blog post, we talk about what happened during an installation of the Tungsten Cluster into an environment with SELinux running and mis-configured.

An attempt to execute `tpm install` on v5.3.2 recently failed with the below error:

ERROR >> node3_production_customer_com >> Unable to run 'sudo systemctl status mysqld.service' or the database server is not running (DatasourceBootScriptCheck) 
Update the /etc/sudoers file or disable sudo by adding --enable-sudo-access=false 

Worse, this customer reported that this appeared as a WARNING only in Dev and Staging tests. So we checked, and it seemed we were able to access systemctl properly:

shell> sudo systemctl status mysqld.service
● mysqld.service - MySQL Percona Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
Active: activating (start-post) since Tue 2018-06-19 17:46:19 BST; 1min 15s ago …
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Mastering Continuent Clustering Series: Configuring Startup on Boot

In this blog post, we talk about how to configure automatic start at boot time for the Tungsten Clustering components.

By default, Tungsten Clustering does not start automatically on boot. To enable Tungsten Clustering to start at boot time, use the deployall script provided to create the necessary boot scripts:

shell> sudo /opt/continuent/tungsten/cluster-home/bin/deployall

To disable automatic startup at boot time, use the undeployall command:

shell> sudo /opt/continuent/tungsten/cluster-home/bin/undeployall

For Multisite/Multimaster deployments in specific, there are separate cross-site replicators running. In this case, a custom startup script must be created, otherwise the replicator will be unable to start as it has been configured in a different directory.

  1. Create a link from the Tungsten Replicator service startup script in the operating system …
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Mastering Continuent Clustering Series: Automatic Reconnect in the Tungsten Connector

In this blog post, we talk about the Automatic Reconnect feature in the Tungsten Connector.

Automatic reconnect enables the Connector to re-establish a connection in the event of a transient failure. Under specific circumstances, the Connector will also retry the query.

Connector automatic reconnect is enabled by default in Proxy and Smartscale modes.

Use the following tpm command option on the command line (remove the leading hyphens inside INI files):

--connector-autoreconnect=false

to disable automatic reconnect.

This feature is not available while running in Bridge Mode. Use the tpm command option --connector-bridge-mode=false to disable Bridge mode.

Automatic reconnect enables retries of statements under the following circumstances:

  • not in bridge mode
  • not inside a transaction
  • no temp table has been created
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Mastering Continuent Clustering Series: Manual Switch Behavior Tuning in the Tungsten Connector

In this blog post, we talk about how existing client connections are handled by the Tungsten Connector when a manual master role switch is invoked and how to adjust that behavior.

When a graceful switch is invoked via cctrl or the Tungsten Dashboard, by default the Connector will wait for five (5) seconds to allow in-flight activities to complete before forcibly disconnecting all active connections from the application side, no matter what type of query was in use.

If connections still exist after the timeout interval, they are forcibly closed, and the application will get back an error.

This configuration setting ONLY applies to a manual switch. During a failover caused by loss of MySQL availability, there is no wait and all connections are force-closed immediately.

This timeout is adjusted via the tpm option …

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Mastering Continuent Clustering Series: Connection Handling in the Tungsten Connector

In this blog post, we talk about how query connections are handled by the Tungsten Connector, especially read-only connections.

There are multiple ways to configure session handling in the Connector. The three main modes are Bridge, Proxy/Direct and Proxy/SmartScale.

In Bridge mode, the data source to connect to is chosen ONCE for the lifetime of the connection, which means that the selection of a different node will only happen if a NEW connection is opened through the Connector.

So if your application reuses its connections, all traffic sent through that session will continue to land on the selected read slave, i.e., when using connection pooling.

http://docs.continuent.com/tungsten-clustering-6.0/connector-bridgemode.html

The key difference is in how the slave latency checking is handled: …

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Complete Megalist: 25 Helpful Tools For Back-End Developers

 

The website or mobile app is the storefront for participating in the modern digital era. It’s your portal for inviting users to come and survey your products and services. Much attention focuses on front-end development; this is where the HMTL5, CSS, and JavaScript are coded to develop the landing page that everyone sees when they visit your site.

 

But the real magic happens on the backend. This is the ecosystem that really powers your website. One writer has articulated this point very nicely as follows:

 

The technology and programming that “power” a site—what your end user doesn’t see but what makes the site run—is called the back end. Consisting of the server, the database, and the server-side applications, it’s the behind-the-scenes functionality—the brain of a site. …

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Percona Live Featured Tutorial with Derek Downey, David Turner and René Cannaò — ProxySQL Tutorial

Welcome to another post in the series of Percona Live featured tutorial speakers blogs! In these blogs, we’ll highlight some of the tutorial speakers that will be at this year’s Percona Live conference. We’ll also discuss how these tutorials can help you improve your database environment. Make sure to read to the end to get a special Percona Live 2017 registration bonus!

In this Percona Live featured tutorial, we’ll meet Derek Downey (OSDB Practice Advocate, Pythian), David Turner (Storage SRE, Uber) and René Cannaò (MySQL SRE, Dropbox / ProxySQL). Their session is ProxySQL Tutorial. There is a stigma attached to database proxies when it comes to MySQL. This tutorial hopes to blow away that stigma by showing you what can be done with a proxy designed from the …

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Upstart Basics for Automatic Restarts of MaxScale After Crash

Historically I do not care much about MariaDB's MaxScale, at least since I know how to build it from source when needed. But, as a support engineer who work at MariaDB, sometimes I have to deal with problems related to MaxScale, and this week it happened so that I had to explain what to do to implement automatic restarts of MaxScale "daemon" in case of crashes on RHEL 6.x.

In the process I had found out that two of my most often used Linux distributions, CentOS 6.x and Ubuntu 14.04, actually use Upstart, so good old System V's init tricks and scripts work there only partially and only because somebody cared to integrate them into this "new" …

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Consul, ProxySQL and MySQL HA

When it comes to “decision time” about which type of MySQL HA (high-availability) solution to implement, and how to architect the solution, many questions come to mind. The most important questions are:

  • “What are the best tools to provide HA and Load Balancing?”
  • “Should I be deploying this proxy tool on my application servers or on a standalone server?”.

Ultimately, the best tool really depends on the needs of your application and your environment. You might already be using specific tools such as Consul or MHA, or you might be looking to implement tools that provide richer features. The dilemma of deploying a proxy instance per application host versus a standalone proxy instance is usually a trade-off between “a less effective load balancing algorithm” or “a single point of failure.” Neither are desirable, but there are ways to implement a solution that balances all …

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