I finally upgraded from Fedora 13 to Fedora 15 on my beloved ASUS-UL30A-X5. It includes the new Gnome 3, with the “Gnome Shell” interface. It’s quite different from anything else I’ve used, and you can read lots of positive and negative impressions around the web.
I bought a Barnes and Noble Nook Color e-book reader and ripped out the Nook software, replacing it with the CyanogenMod distribution of the Android OS. It’s really, really nice hardware, and CyanogenMod (CM) is really, really nice software. I love them both, and my regular readers will remember that I’m not a gadget guy. Read on for more.
A few day ago, a customer came to Percona needing to recover data. Basically, while doing a transfer from one SAN to another, something went wrong and they lost the ibdata1 file, where all the table meta-data is stored. Fortunately, they were running with innodb_file_per_table so the data itself was available. What they could provide us was:
Their first question was “Is it possible to recover the data?”
One of item I always look at SHOW ENGINE INNODB STATUS to see if there are any transactions spending very long time in ACTIVE state. In the perfect world if you’re running online system you should not see transactions spending more than couple of seconds in ACTIVE state. Especially ACTIVE transactions which do not currently run any query are suspicious. There are however cases when screaming fire about ACTIVE transactions alone would be misleading. There is a whole set of applications which run quite fine while having ACTIVE measured in hours.
Today was another example of where a correct SQL_MODE saved customer data from being corrupted. By default, MySQL does not enforce data integrity. It allows what is called silent truncations where the result of what you INSERT or UPDATE does not represent truth. NOTE: I see very few customers ever have this correctly configured, those that do have actually listened to my advice.
At Percona Live last week, someone showed me a graph from their Cacti monitoring system, using the templates that I wrote. It was the buffer pool pages read, written, and created. He asked me if the graph was okay. Shouldn’t there be a lot more pages read than written, he asked? It’s a great question.