Author Archives: Tor Henning Ueland
Guice: java.lang.IllegalStateException: No SessionHandler or SessionManager
One reason for this error would be that you should inject the session object directly, not via constructor: So instead of: @Singleton public class Foo { @Inject public Foo(HttpServletSession s) { this.session = s } } do this: @Singleton … Continue reading
Expanding a kVM disk image
Had to expand a KVM virtual machine today. Luckily, that`s pretty straight forward. You simply create a new disk image with the extra size needed, merge it into the original disk and voila. Then you just need to partition in … Continue reading
Cannot open exchanger control device ([2] The system cannot find the file specified)
You will receive this error from (among others) Data Protector if the D2D/Tape unit has gone offline, or is not reachable from the machine controlling it. Normally the Data Protector cell manager. In Windows 2008 server you can make sure that Windows is … Continue reading
Tuning Ubuntu mdadm RAID5/6
If you are using mdadm RAID 5 or 6 with Ubuntu, you might notice that the performance is not all uber all the time. Reason for this is that the default tuning settings for Ubuntu is set to rather motdest … Continue reading
class Foo is public, should be declared in a file named Foo.java
When working with Java you might encounter this error. The reason for this is that you have tried to declare a public class in a file with a different name. Each java file can only contain one public java class, … Continue reading
WordPress giving maintenance error message
If you have tried to upgrade a WordPress plugin or WordPress itself, and failed. You might have ended up with your blog only returning “Briefly unavailable for scheduled maintenance. Check back in a minute.” error message. The reason for this … Continue reading
Change hostname on Linode VPS
Linode explains pretty well how to change the hostname of your VPS. But they do not mention that in the latest Ubuntu it is set via Linode`s own DHCP server. So even if you set it via /etc/hostname and in … Continue reading
Guide: Solr performance tuning
Introduction I have for the last year been working a lot with the Solr search engine, and figuring out how to get the best performance from a Solr instance. And it is almost funny how much impact the little things … Continue reading
404 checker updated
My old 404 checker had a problem with timeouts etc when parsing large pages. I have now updated it to handle larger sites better, it does now also give response for each link checked as it get`s checked.
Clear disk cache on Linux
I have been doing a bit benchmarking in the previous days, and have then needed to clear the disk cache from RAM without wanting to reboot each time. The command i use for that is: 1 sync;echo 3 > /proc/sys/vm/drop_caches … Continue reading