I’m finally getting around to blogging in the techsphere. It’s about time I know but that’s cause my job usually keeps me too busy. Then there’s the side volunteer gig as a co-host of sfmysql.org (sf MySQL meetup!). That takes a chunk of time (lately more than I’d like, but that’s another post/rant).
I keep up on my blogs via google reader. Generally MySQL planet keeps me up to date. Lately there’s been a lot of talk about what happens when the master database fails (whether it’s really failing or scripts think it’s failing). The biggest surprise is that maintenance is causing problems when promoting the passive master (really just a slave no apps read from) due to a cold InnoDB cache. I mean, REALLY FOLKS!! There’s a tool for that!
I think Percona needs to blog about how to use their tools more. At a gig where I was working with this cracker-jack SysAdmin who was always on my case to push the envelope, I told him about a script that used maatkit’s mk-query-digest for a bit now & it works well. (Ryan Lowe gave me some hints at the talk he gave at sfmysql.org & I slightly modified it. ) In the past this is how I warmed up the passive master. We didn’t even have a passive master at the time & I was making a case for it. So he gave me one. I piped all my reads over to the passive master. I also modified all writes to be reads and piped those over. We did a table checksum. All was good with the data. Then we failed over to the passive master.
Whoa! no dip in response time. Granted we piped over this traffic for 4 hours (or was it 6?). But it worked. I wondered why we couldn’t just keep that script running all the time. We hadn’t removed the analytics stuff yet so there was too much traffic but we crontab’d it to happen a couple of times in the day & more so during slow hours. If I know I’m doing maintenance to a Master, I always, always warm up the cache. And yes, there’s a tool for that! (thank you maatkit authors & maintainers & thank you Percona!)
The doc for pt-query-digest is here: http://www.percona.com/doc/percona-toolkit/2.1/pt-query-digest.html In the near future I’ll add parts of the script!
Ps. I’m currently looking for a MySQL DBA position in the CITY of San Francisco. I’m a startup freak because I like to do a bit more than just admin the mysql servers. I’m interested in admin’ing Redis, MongoDB (other NoSQL technology) and scalability of data. I love learning new technology that works so well with MySQL!