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When looking at high availability for any CMS, and particularly for Drupal, the list of contenders for part or all of the solution is growing and can be daunting. We'll take a look at the various parts of a solution and what options we have.
It seems nearly every answer to every problem in IT these days is "The Cloud", but is it?
Selecting the most appropriate solution for a MySQL HA infrastructure is as much a business and philosophical decision as it is a technical one, but often the choice is made without adequately considering all three perspectives. When too much attention is paid to one of these aspects at the cost of the others, the resulting system may be over-engineered, poorly-performing, and/or various other flavors of suboptimal.
On Wednesday, June 5, at 10 a.m. PDT (1700 UTC), I will be presenting a webinar entitled, Choosing a MySQL HA Solution, in
[Read more...]Drupal is one of the most popular Content Management Systems (CMS) and is used increasingly in high-visibility sites, such as www.whitehouse.gov. This has brought a lot of attention on how to get the most performance out of Drupal and how to improve the availability of such sites. In this blog series I'll take you through the basics and on through to designing your own HA Drupal site.
But first, we need to understand what the challenges are in getting Drupal (or indeed any CMS) working on multiple servers in such a way as to ensure high availability and performance.
Drupal is one of the most popular Content Management Systems (CMS) and is used increasingly in high-visibility sites, such as www.whitehouse.gov. This has brought a lot of attention on how to get the most performance out of Drupal and how to improve the availability of such sites. In this blog series I'll take you through the basics and on through to designing your own HA Drupal site.
But first, we need to understand what the challenges are in getting Drupal (or indeed any CMS) working on multiple servers in such a way as to ensure high availability and performance.
Good morning Percona Live visitors! Attached to this post you can find a spreadsheet (both LibreOffice or Excel, as you prefer) that you can use towards the end of my tutorial. I've also attached the slides so you can download a copy of them.
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We were delighted last week to find out that we’d been named one of the ‘2013 Top 100 Europe’ winning companies by the Red Herring editorial team. Congratulations to all companies involved!
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We were delighted last week to find out that we’d been named one of the ‘2013 Top 100 Europe’ winning companies by the Red Herring editorial team. Congratulations to all companies involved!
Swapping has always been something bad for MySQL performance but it is even more important for HA systems. It is so important to avoid swapping with HA that NDB cluster basically forbids calling malloc after the startup phase and hence its rather complex configuration.
Probably most readers of this blog know (or should know) about Linux swappiness setting, which basically controls how important is the file cache for Linux. Basically, with InnoDB, since the file cache is not important we add “vm.swappiness = 0″ to “/etc/sysctl.conf” and run “sysctl -p” and we are done.
Swappiness solves part of the swapping issue but not all. With Numa systems, the picture is more complex and swapping can occur because of a memory imbalance between the physical cpus, the sockets and not cores. Jeremy Cole explained this
[Read more...]Read the original article at Crashed nodes corrupt your MySQL cluster
Writing to two masters is like walking around with a loaded shotgun. Eventually one of your instances will fail and when it does, replications position & synchronization information could easily become corrupt! Reason 8 – Crashed nodes cause big problems MySQL instances, unfortunately can crash. When that happens, they don’t always sync the replication position [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at Transaction isolation breaks when writing two masters
Continuing our discussion of multi-master replication, we hit on five more reasons why writing to two masters aka active-active replication is very dangerous. Click through to the end for multi-master solutions that work with MySQL. Reason 6 – You lose transaction isolation This may sound like a theoretical point to some. But hopefully we can [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at Active-active replication reduces operational flexibility
Among the myriad data integrity and corruption risks associated with active-active replication, you also lose out on configurability and operational flexibility. Reason 7 – Can’t add nodes easily The often touted solution to use auto_increment_increment and auto_increment_offset fixes you to a given setup forever. You can set it up with a discrete two nodes, all [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at How to make MySQL multi-master work for you
Coming soon! Want more? Grab our Scalable Startups monthly for more tips and special content. Here’s a sample Related posts:Transaction isolation breaks when writing two masters MySQL requires an authoritative master to build slaves MySQL needs single master to check data integrity A master isn’t born but made Why does MySQL replication fail?
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at MySQL needs single master to check data integrity
MySQL slaves can drift out of sync. Many of our clients are surprised to find some data differences in their replication topology, once we do some checking and sniffing around. Such checks require a single reliable or authoritative master to compare against. Click through to the end for multi-master solutions that work with MySQL. Reason [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at MySQL requires an authoritative master to build slaves
In MySQL database operations, you often need to rebuild slaves. They fail for a lot of different reasons, fall out of sync or crash. When this happens you may find you need to reclone and start fresh. This is normally done by finding your authoritative master database, and doing a hotbackup. Click through to the [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at Limitations of MySQL row-based replication
MySQL offers a few different options for how you perform replication. Statement-based has been around a lot longer, and though it has some troublesome characteristics they’re known well and can be managed. What’s more it supports online schema changes with multi-master active-passive setup. We recommend this solution. Row-based replication is newer. It attempts to address [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at 10 reaons active-active is hard and how to solve it
Multi-master replication provides redundant copies of your most important business assets. What’s more it allows applications to scale out, which is perfect for cloud hosting solutions like Amazon Web Services. But when you decide you need to scale your write capacity, you may be considering active-active setup. This is dangerous, messy and prone to failure. [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Read the original article at Why does MySQL replication fail?
When considering active-active multi-master, you must consider it’s foundation technology. Although MySQL replication is straightforward to setup, it can fail in a myriad of ways. Most of those are known and well understood. We can solve them only if we use the technology in the standard way. Click through to the end for multi-master solutions [...]
For more articles like these go to Sean Hull's Scalable Startups
Related posts:Update – the recording of this webinar is now available here.
This Wednesday (27th March) Mat Keep and I will be presenting a free, live webinar on MySQL 5.6 Replication. You need to register here (http://www.mysql.com/news-and-events/web-seminars/mysql-5-6-replication-enabling-next-generation-of-web-mobile-social-and-cloud-services/" target="_blank) ahead of the webinar – worth doing even if you can’t attend as you’ll then be sent a link to the replay when it’s available. We’ll also have some of the key MySQL replication developers
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Multi-Threaded Slave
MySQL 5.6 has now been declared Generally Available (i.e. suitable for production use). This is a very exciting release from a MySQL replication perspective with some big new features. These include:Standard MySQL is configurable such that a single master server can be clustered with a number of read-only slave servers. To enable this master-slave replication, master’s transaction logs are communicated to the slaves (log shipping). Log shipping is a form of asynchronous replication. Under this configuration, the data on the slave always remains behind the master, a condition referred to as slave lag or replication lag. The extent of the slave lag depends on workload, network bandwidth and network latency. Database reads can be served out of the slaves, assuming the application has been designed to tolerate the slave lag and requisite staleness of data (eventual consistency), which can at times be variable and opaque. MySQL master-slave replication offers the possibility of promoting a slave to become the new master
[Read more...]
If you're planning to attend UKOUG in Birmingham on Dec 3-5, here's your guide to know more about Oracle's MySQL.Read the original article at AirBNB didn’t have to fail
Today part of Amazon Web Services failed, taking down with it a slew of startups that all run on Amazon’s Cloud infrastructure. AirBNB was one of the biggest, but also Heroku, Reddit, Minecraft, Flipboard & Coursera down with it. Its not the first time. What the heck happened, and why should we care?
The AWS service allows companies like AirBNB to build web applications, and host them on servers owned and managed by Amazon.
[Read more...]Oracle has announced that it now provides support for DRBD with MySQL – this means a single point of support for the entire MySQL/DRBD/Pacemaker/Corosync/Linux stack! As part of this, we’ve released a new white paper which steps you through everything you need to do to configure this High Availability stack (http://www.mysql.com/why-mysql/white-papers/mysql_wp_drbd.php). The white paper provides a step-by-step guide to installing, configuring, provisioning and testing the complete MySQL and DRBD stack, including:
DRBD is an extremely popular way of adding a layer of High
[Read more...]Attached are the slides for my MySQL Connect talk Evaluating MySQL High-availability alternatives, which I will present today at 14:30 at the MySQL Connect conference.
A bit unusually I'm posting the material ahead of the talk. The point of the talk is about evaluating each alternative from your own perspective. With that in mind, if you're at the talk with your own laptop, feel free to browse the slides at your own pace from here.
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