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Showing entries 1 to 10 of 21 10 Older Entries

Displaying posts with tag: Software and tools (reset)

Slow Query Log Rotation
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Some time ago, Peter Boros at Percona wrote this post: Rotating MySQL slow logs safely. It contains good info, such as that one should use the rename method for rotation (rather than copytruncate), and then connect to mysqld and issue a FLUSH LOGS (rather than send a SIGHUP signal).

So far so good. What I do not agree with is the additional construct to prevent slow queries from being written during log rotation. The author’s rationale is that if too many items get written while the rotation is in process, this can block threads. I understand this, but let’s …

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LKML: Live patching for 3.20
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Building on the original kSplice idea and combining the efforts of the work done at Red Hat and SuSE, common infrastructure is now ready to be put into the Linux 3.20 mainline kernel – Red Hat and SuSE have already committed to using this.

I still reckon it’s freaky trickery, but heck – it works, and it’s great for server environments that have no redundancy (I prefer to fix that issue!) and can’t afford any downtime.

Munin graphing of MySQL
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While there are many graphing tools out there and we’ve used Munin for a while now.

The MySQL plugin for Munin had fallen out of date and the show engine innodb status output changed in 5.5 making some bits of the plugin simply not work any more. Also the show global status has some extra variables so there was a need to create new graphs.

All of these are now in the 2.1.8+ development releases of Munin.

Here are samples of the new/updated graphs.

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MySQL Connector/Arduino
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Chuck Bell, one of my former colleague from MySQL AB, has created a connector for Arduino to MySQL. So this allows Arduino code to be a direct client of a MySQL or MariaDB server, with Ethernet and WiFi shields supported.

With Arduino boards being used more and more, this can come in really handy – not only for retrieving (for instance) centralised configuration data, but also for logging. Useful stuff. Thanks Chuck!


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Storage caching options in Linux 3.9 kernel
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dm-cache is (albeit still classified “experimental”) is in the just released Linux 3.9 kernel. It deals with generic block devices and uses the device mapper framework. While there have been a few other similar tools flying around, since this one has been adopted into the kernel it looks like this will be the one that you’ll be seeing the most in to the future. It saves sysadmins the hassle of compiling extra stuff for a system.

A typical use is for an SSD to cache a HDD. Similar to a battery backed RAID controller, the objective is to insulate the application from latency caused by the mechanical device, the most laggy part of which is seek time …

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Optimising Web Servers
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I was lucky enough to attend PyCon-AU recently and one talk in particular highlighted the process of web server optimisation.

Graham Dumpleton’s add-in talk Web Server Bottlenecks And Performance Tuning available on YouTube (with the majority of PyCon-AU talks)

The first big note at the beginning is that the majority of the delay in user’s perception of a …

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Jetpants: a toolkit for huge MySQL topologies
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From a Tumblr engineering blog post:

Tumblr is one of the largest users of MySQL on the web. At present, our data set consists of over 60 billion relational rows, adding up to 21 terabytes of unique relational data. Managing over 200 dedicated database servers can be a bit of a handful, so naturally we engineered some creative solutions to help automate our common processes.

Today, we’re happy to announce the open source release of Jetpants, Tumblr’s in-house …

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MySQL Cluster on Raspberry Pi
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Earlier this week, Andrew Morgan wrote a piece on running MySQL Cluster on Raspberry Pi. Since the term “Cluster” is hideously overloaded, I’ll note that we’re talking about the NDB cluster storage engine here, a very specific architecture originally acquired by MySQL AB from Ericsson (telco).

Raspberry Pi is a new single-board computer based on the ARM processor series (same stuff that powers most mobile phones these days), and it can …

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Green HDs and RAID Arrays
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Some so-called “Green” harddisks don’t like being in a RAID array. These are primarily SATA drives, and they gain their green credentials by being able reduce their RPM when not in use, as well as other aggressive power management trickery. That’s all cool and in a way desirable – we want our hardware to use less power whenever possible! – but the time it takes some drives to “wake up” again is longer than a RAID setup is willing to tolerate.

First of all, you may wonder why I bother with SATA disks at all for RAID. I’ve written about this before, but they simply deliver plenty for much less money. Higher RPM doesn’t necessarily help you for a …

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HDlatency – now with quick option
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I’ve done a minor update to the hdlatency tool (get it from Launchpad), it now has a –quick option to have it only do its tests with 16KB blocks rather than a whole range of sizes. This is much quicker, and 16KB is the InnoDB page size so it’s the most relevant for MySQL/MariaDB deployments.

However, I didn’t just remove the other stuff, because it can be very helpful in tracking down problems and putting misconceptions to rest. On SANs (and local RAID of course) you have things like block sizes and stripe sizes, and opinions on what might be faster. Interestingly, the real world doesn’t always agree …

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Showing entries 1 to 10 of 21 10 Older Entries

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