First write operation to large ext4 file system is slow

I'm running a large (>20TB) ext4 file system and noticed that the first substantial write operation after mounting is very slow and involves plenty of drive activity. The reason seems to be some memory structure initialisation as described here: https://linux-ext4.vger.kernel.narkive.com/SUFNE520/ext4-slow-performance-on-first-write-after-mount The workaround is thankfully as simple as running this command in a script after mounting … Continue reading First write operation to large ext4 file system is slow

Resetting a PCI device

The Wi-Fi adapter on my VivoBook 17 has been acting up under Ubuntu 18.04 LTS insofar that at a random point in time, possibly accelerated by power saving features, the Wi-Fi will stop working with suspicious syslog entries: ath10k_pci 0000:03:00.0: failed to wake target for read32 at 0x0003a028: -110 The usual tricks (suspend/resume, reload driver, … Continue reading Resetting a PCI device

Increasing window resize corner in Ubuntu 12.04

Resizing a window in Unity/Ubuntu 12.04 is quite a pain as one needs to target the 1 pixel border of the lower right corner. Fortunately the width can be increased: Edit /usr/share/themes/Ambiance/metacity-1/metacity-theme-1.xml and increase the widths, i.e.:   <distance name="left_width" value="8"/>   <distance name="right_width" value="8"/>   <distance name="bottom_height" value="8"/> Log out and in again.

HTTP: The importance of declaring non-cachable resources as such

It works fine with Chrome and it fails on an Android 2.3 browser - the page is performing an XmlHttpRequest to the server for a resource that just changed for sure and yet it gets back an older version. That's the result of a. the browser assuming a resource is cachable even if no Etag … Continue reading HTTP: The importance of declaring non-cachable resources as such

sshfileuploader: uploading large files over ssh over an unreliable connection

I'm having for the last month a very bad internet connection which makes it almost impossible to upload files anywhere: drive, facebook or WARs to my toy server. Especially the latter one is really annoying as the SSH connection will really abort with an ugly network error. I suspect a misconfiguration in the TCP/IP settings … Continue reading sshfileuploader: uploading large files over ssh over an unreliable connection

mdadm woes

After migrating a software RAID 5 to Ubuntu LTS 12.04, the system wouldn't come up again after rebooting. I believe Chris Siebenmann to splendidly have analysed [1] the problem: a race condition with udev losing the race. His solution is to: Change /usr/share/initramfs-tools/scripts/mdadm-functionsas follows: degraded_arrays() { + udevadm settle mdadm --misc --scan --detail --test >/dev/null … Continue reading mdadm woes

Internet Explorer, zooming and resize events

My current project (cat4trad) for the European Parliament, which involves heavily GWT and javascript in bringing a seamless user experience to translators, we frequently run into issues with different browsers. The one I run into today was about a window resize event not being detected by IE8 and IE9. This simple test should always print … Continue reading Internet Explorer, zooming and resize events