Tag Archives: mysql

Operationalizing TokuDB

In my previous post, I talked about implementing multi-threaded replication (MTR) using Percona Server 5.6. The server pairs that are utilizing MTR are also exclusively using the TokuDB storage engine.

I find TokuDB to be a fascinating engine. I can tell I will need to re-watch our Dbhangops session where Tim Callaghan talked about the differences between B-Tree and Fractal Tree indexes. There’s also a session on how compression works in TokuDB and they continue to innovate with read-free replication.

As with all new technology, there is a learning curve to understanding a new component or system. I thought it appropriate to try to document my experiences on operationalizing TokuDB into our environment. This is no where near comprehensive as I just don’t have enough experience with it yet to know the deeper intricacies of the engine.

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XFS and EXT4 Testing Redux

In my concluded testing post, I declared EXT4 my winner vs XFS for my scenario. My coworker, @keyurdg, was unwilling to let XFS lose out and made a few observations:

  • XFS wasn’t *really* being formatted optimally for the RAID stripe size
  • XFS wasn’t being mounted with the inode64 option which means that all of the inodes are kept in the first 2TB. (Side note: inode64 option is default in newer kernels but not on CentOS 6’s 2.6.32)
  • Single threaded testing isn’t entirely accurate because although replication is single threaded, the writes are collected in InnoDB and then writes it to disk using multiple threads governed by innodb_write_io_threads.

Armed with new data, I have – for real – the last round of testing.

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IO, IO, It’s Off to Testing We Go

In my last post, I learned in disappointing fashion that sometimes you need to start small and work your way up, rather than trying to put together a finished product. This go-round, I’ll talk about my investigation into disk IO.

In an effort to better understand the hardware I have and it’s capacities, I started off by just trying to get some basic info about the RAID controller and the disks. This hardware in particular is a Supermicro, with a yet unknown RAID controller and 16 4TB disks arranged in RAID 6. Finding out more disk and controller information was the first step. “hdparm -i” wasn’t able to give me much, nor was “cat /sys/class/block/sdb/device/{model,vendor}”. “dmesg” got me to a list of hard disks, Hitatchi 7200rpm and a model number that I could Google. It also got me enough controller information to point to megaraid, which is LSI, which got me over to this MegaCli cheat sheet. Using “MegaCli -AdpAllInfo -aALL” actually got me a great deal of information. (In other news, I now think that Dell’s OMSA command line utility is a lot less terrible after trying to figure out MegaCli).

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Even If You Fail, You Can Still Learn

As many learning experiences do, this one also starts out “So I was working on a project at work and…”.  In this case, the end result is to try to run as many concurrent copies of MySQL on a single server as possible, maintaining real time replication each running differing data sets. To help with this, I sent out to do this on a server with 36 7200rpm 4GB SATA disks, giving me roughly 120TB of available space to work with.

This isn’t an abnormal type of machine for us. Sometimes you simply need a ton of disk space. There is a quirk with this particular machine that I’ve been told: the RAID controller has some issues with addressing very large virtual disks and I should create 2 60TB volumes and stitch them together with LVM. Easy enough: pvcreate both volumes, create a volume group and a logical volume out of it and viola: ~116TB of storage on a single mount point, with xfs as the file system (default options).

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A Smattering of Percona Live 2014 Stuff

A real fast list of stuff from the Percona Live 2014 event.

Yahoo’s Performance Analyzer

Yahoo is developing a MySQL performance analyzer that should be released as open source later this year. From the demo, it looks like it pulls in most of the MySQL metrics, shows you a processlist and then lets you drill into a processlist with explain. Will have to keep my eye out for this.

ChatOps with Hubot

GitHub’s Sam Lambert has a set of hubot chatops scripts for MySQL. I was already looking at depoying hubot for the ability to push messages from a remote source into an IRC channel, so this would be a natural fit. He also mentioned using Janky to tie CI with hubot.

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