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!
Apr
21
2013
Apr
19
2013
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 here and …
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Apr
18
2013
Here’s the last nail in the coffin. We hope this convinces you not to write to multiple masters with MySQL replication. Reason 10 – No tools to reconcile inconsistent masters For all the endless reasons we’ve already outlined MySQL replication is prone to failure. We know it’s going to happen, you now know too. When [...]
Apr
18
2013
If you’re not convinced yet that writing to dual masters is a bad idea, we have a couple more reasons. 9. Temp tables break replication after restart MySQL’s replication is sensitive to temporary tables. You shouldn’t use them. If your queries create them to work against, and a node crashes, the temp tables will be [...]
Apr
18
2013
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 [...]
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Apr
18
2013
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 [...]
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Apr
18
2013
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 [...]
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Apr
16
2013
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?
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Apr
16
2013
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 [...]
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Apr
16
2013
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 [...]
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