Here is a quick guide to getting a plain ZFS partition working on a Linux machine using the “ZFS on Linux” project. I was playing around on a CentOS 7 virtual machine trying to set it up as a replication target for my home FreeNAS box as a backup. If you are unfamiliar with ZFS, it is a filesystem for a storage environment, having features such as data integrity protection and snapshots; I came across it as it is used in FreeNAS. Here is the procedure I used:
Dennis
I am currently a software developer at A Thinking Ape Entertainment Ltd. I graduated from the University of British Columbia with a B.Sc. degree in Computer Science with the Software Engineering Option. I primarily speak Python and C# these days, but in the past I've also done Objective-C, Java and PHP.
Outside of work, I'm a volunteer on the youth ministry team at St. Francis Xavier Catholic Church, and also on the Canadian Ski Patrol team at Mount Seymour. I'm also an avid transit enthusiast/photographer.
VMware ESXi Scratch Space
If you installed VMware ESXi on a USB stick like I did, the “scratch space” (used for storing logs and debug information) is stored on a RAM disk. This takes up 512MB of memory that could otherwise be provisioned to virtual machines. In addition, it does not persist across reboots, which explains why I was never able to find any logs after a crash. Also I was seeing random “No space left on device” errors when I was trying to run the munin monitoring script for ESXi. The solution to this is to simply create a folder on a disk, and Continue Reading
Seven years after Youth Leadership Millennium
Last Saturday I had the opportunity to attend the graduation ceremony of this year’s S.U.C.C.E.S.S. Youth Leadership Millennium (YLM) program. I participated in the same program seven years ago and since then have been volunteering there. Although I have attended many of the graduations as a volunteer over the past years, this was the first time I was invited to speak in front of the audience from my perspective as an alumnus. Writing the speech gave me a chance to reflect over the past seven years and how different aspects of YLM have been part of my life. Much of what Continue Reading
How did advertisements get on my site?
Disseminating the sneakiness behind the Shareaholic WordPress plugin, which added ad links to sites without the owners’ opting in.
Checking for a Null value in SQL
Yesterday I fell into a very simple but dangerous SQL trap. Can you identify it? Found it? It’s the comparison to null. My intention was to get rows where another_column was null, however the query did not do so. It didn’t give me any results where another_column was null, but didn’t give me any error either. Why? Null in SQL is not a real value. Null means “lack of a value” or “unknown”. Anything compared to null leads to an “unknown” result. Therefore, in SQL there are actually three values conditions can evaluate to: true, false, and unknown/null. This is called Continue Reading