Personal blog of Yzmir Ramirez

 Like Box’s last quarterly check-in, the company once again touted that it had free cash flow in the first quarter this year as part of its Q1 earnings report today — a signal that Wall Street may be looking for as a barometer of its future health as a company. Read More

 Here are the must-read stats about what’s happening with internet adoption, smartphones, ads, e-commerce, entertainment, gaming, enterprise healthcare, China, India and startups. We’ve picked the most important slides from legendary Kleiner Perkins partner Mary Meeker’s massive 355-page 2017 Internet Trends report, deciphered the complex data and explained why… Read More

 Here are the must-read stats about what’s happening with internet adoption, smartphones, ads, e-commerce, entertainment, gaming, enterprise healthcare, China, India and startups. We’ve picked the most important slides from legendary Kleiner Perkins partner Mary Meeker’s massive 355-page 2017 Internet Trends report, deciphered the complex data and explained why… Read More

In this blog post, we’ll look at how Percona XtraDB Cluster maintenance mode uses ProxySQL to take cluster nodes offline without impacting workloads.

Percona XtraDB Cluster Maintenance Mode

Since Percona XtraDB Cluster offers a high availability solution, it must consider a data flow where a cluster node gets taken down for maintenance (through isolation from a cluster or complete shutdown).

Percona XtraDB Cluster facilitated this by introducing a maintenance mode. Percona XtraDB Cluster maintenance mode reduces the number of abrupt workload failures if a node is taken down using ProxySQL (as a load balancer).

The central idea is delaying the core node action and allowing ProxySQL to divert the workload.

How ProxySQL Manages Percona XtraDB Cluster Maintenance Mode

With Percona XtraDB Cluster maintenance mode, ProxySQL marks the node as OFFLINE when a user triggers a shutdown signal (or wants to put a specific node into maintenance mode):

• When a user triggers a shutdown, Percona XtraDB Cluster node sets

  pxc_maint_mode

   to SHUTDOWN (from the DISABLED default) and sleep for x seconds (dictated by

  pxc_maint_transition_period

    — 10 secs by default). ProxySQLauto detects this change and marks the node as OFFLINE. With this change, ProxySQL avoids opening new connections for any DML transactions, but continues to service existing queries until

  pxc_maint_transition_period

  . Once the sleep period is complete, Percona XtraDB Cluster delivers a real shutdown signal — thereby giving ProxySQL enough time to transition the workload.

• If the user needs to take a node into maintenance mode, the user can simply set

  pxc_maint_mode

   to MAINTENANCE. With that, 

  pxc_maint_mode

   is updated and the client connection updating it goes into sleep for x seconds (as dictated by

  pxc_maint_transition_period

  ) before giving back control to the user. ProxySQL auto-detects this change and marks the node as OFFLINE. With this change ProxySQL avoids opening new connections for any DML transactions but continues to service existing queries.

• ProxySQL auto-detects this change in maintenance state and then automatically re-routes traffic, thereby reducing abrupt workload failures.

Technical Details:

• The ProxySQL Galera checker script continuously monitors the state of individual nodes by checking the

  pxc_maint_mode

   variable status (in addition to the existing

  wsrep_local_state

  ) using the ProxySQL scheduler feature

• Scheduler is a Cron-like implementation integrated inside ProxySQL, with millisecond granularity.
• If

  proxysql_galera_checker

   detects

  pxc_maint_mode = SHUTDOWN | MAINTENANCE

  , then it marks the node as OFFLINE_SOFT.  This avoids the creation of new connections (or workloads) on the node.

Sample

proxysql_galera_checker

 log:

Thu Dec  8 11:21:11 GMT 2016 Enabling config
Thu Dec  8 11:21:17 GMT 2016 Check server 10:127.0.0.1:25000 , status ONLINE , wsrep_local_state 4
Thu Dec  8 11:21:17 GMT 2016 Check server 10:127.0.0.1:25100 , status ONLINE , wsrep_local_state 4
Thu Dec  8 11:21:17 GMT 2016 Check server 10:127.0.0.1:25200 , status ONLINE , wsrep_local_state 4
Thu Dec  8 11:21:17 GMT 2016 Changing server 10:127.0.0.1:25200 to status OFFLINE_SOFT due to SHUTDOWN
Thu Dec  8 11:21:17 GMT 2016 Number of writers online: 2 : hostgroup: 10
Thu Dec  8 11:21:17 GMT 2016 Enabling config
Thu Dec  8 11:21:22 GMT 2016 Check server 10:127.0.0.1:25000 , status ONLINE , wsrep_local_state 4
Thu Dec  8 11:21:22 GMT 2016 Check server 10:127.0.0.1:25100 , status ONLINE , wsrep_local_state 4
Thu Dec  8 11:21:22 GMT 2016 Check server 10:127.0.0.1:25200 , status OFFLINE_SOFT , wsrep_local_state 4

Ping us below with any questions or comments.

www.talkingdrupa.com/148

In episode #148 we talk Drupal system settings and how you can use them.

Show Topics

• What are system settings?
• Use cases
• Using systems settings in Drupal 7 and Drupal 8

Resources

D7 system settings form

Change record for variable set get del

Config Object D8

How to upgrade D7 variables to D8’s state system

Module of the Week

Neutral Paths

A module for multi-language web sites, allowing users to access content in languages other than the current one by using path aliases.

Hosts

Stephen Cross – www.ParallaxInfoTech.com @stephencross

Nic Laflin – www.nLightened.net @nicxvan

John Picozzi – www.oomphinc.com @johnpicozzi

www.talkingdrupa.com/148

In episode #148 we talk Drupal system settings and how you can use them.

Show Topics

• What are system settings?
• Use cases
• Using systems settings in Drupal 7 and Drupal 8

Resources

D7 system settings form

Change record for variable set get del

Config Object D8

How to upgrade D7 variables to D8’s state system

Module of the Week

Neutral Paths

A module for multi-language web sites, allowing users to access content in languages other than the current one by using path aliases.

Hosts

Stephen Cross – www.ParallaxInfoTech.com @stephencross

Nic Laflin – www.nLightened.net @nicxvan

John Picozzi – www.oomphinc.com @johnpicozzi

 This is the best way to get up to speed on everything going on in tech. Kleiner Perkins venture partner Mary Meeker’s annual Internet Trends report is essentially the state of the union for the technology industry. The widely anticipated slide deck compiles the most informative research on what’s getting funded, how Internet adoption is progressing, which interfaces are resonating,… Read More

 CoreOS is hosting its user conference in San Francisco today. Unsurprisingly, the company had a few announcements to make at the event. Most of these centered around its Tectonic platform for managing Kubernetes-based container infrastructures. For the most part, these updates are pretty straightforward. Tectonic now uses the latest version of Kubernetes, for example (1.6.4), which the… Read More

 You probably still get plenty of snail mail at your home — wedding invitations, bills, ads for new credit cards. But despite all the efforts to kill that snail mail and get it sent directly to an inbox, there really doesn’t yet seem to be a replacement to that experience of getting home and stepping over those letters from businesses. That’s a business Lob wants to lock up. Read More

 Concord wants to be your all-in-one solution for everything related to contracts. The startup just raised a $3.7 million Series A round from Alven Capital, with existing investors Streamlined Ventures, Bruno Deschamps and Thibault Poutrel also participating. Many departments rely on contracts to work with clients, suppliers, legal partners and more. But it’s still a tedious process as… Read More