Half way through setting up continuous deployment with jenkins and ansible, I sporadically spotted “unknown errors” with ssh connections when ansible tried to run things on a series of hosts. Searching for “SSH encountered an unknown error during the connection” obviously revealed a LOT of results but nothing that really helped. So I had to dig deeper and eventually found the problem.
Migrating a VM from its primary to secondary node is usually a very simple task for ganeti. But with busy machines, it sometimes, apparently, does not work. Here’s what helped me solve this situation.
Until recently, I worked with a rather basic setup of virtual machine hosts. Simply a couple of servers that ran their individual set of VMs. In case of an outage of one of the nodes, all the nodes’ VMs were also affected. That needed change, so I looked at and found ganeti to be something that might help to provide redundancy for the VMs without introducing too much voodoo. Here’s how I migrated the 140 VMs from 17 machines into one cluster.
With our first kid, me and my wife created new photobooks about every 3 months. Once the second kid arrived, we could not make that happen (everyone who has kids will understand …). He is almost 14 months old now, we have not created a single book yet and I am tasked with creating a photobook from the horrible amount of 25 thousand files. And of course, not only did we not create a photobook for a over a year, we also did not create the “good” folders …
One of the things you do as a young parent is to take tons and tons of pictures of your kids. And then, since you cannot and will never look at all of them digitally, but you also don’t want to forget about all those moments you captured, you create photobooks with some of the best of those pictures. Problem is, you don’t really have the time to organize and sort them. Still, doing this quickly becomes very important once you experience how fast things go by, so here’s my “best practice” and some helpers that get me from “a looooot of files” to “a photobook” in a reasonable amount of time.
Sometimes you find things are possible that you have worked around year after year. Like this little scp switch I encountered today.
Since my old xbmc running media centre pc broke and I had to get a replacement, I recently bought a raspberry pi. For those who haven’t heard of that: It’s a computer as small as a tissue pack that only costs like 30 Euros which – according to many many people on the internet and also my colleagues at work – is capable of playing HD video. Honestly, I didn’t believe it, but for 30 bucks? Let’s try and see …