Topic: Computer

Hardware, software & hacks

Nextcloud Office

In the meantime I have been using Nextcloud on my own servers for several years and also an Office integration in order to be able to edit documents together with others directly in the browser. Originally, I chose OnlyOffice because it was much more mature than Collabora in 2018.

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Home Assistant

Tasmota, web interfaceRecently I’ve been working on a small craft project: extending an IKEA Vindriktning air quality sensor with a D1 Mini to read the data and forward it to a server via MQTT.

See also Sören Beye’s Github repository for the conversion. However, instead of this firmware, I use Tasmota based on these instructions from Blakadder, which is much more convenient to set up and configure. See also the Tasmotizer on Github.

When I was looking for a suitable server, I quickly ended up at Home Assistant. This is a free software solution for integrating numerous smart home devices and can also be used on a Raspberry Pi 3 or 4. In my case this is a Raspberry Pi 4.

Update 2022-08-14: In the meantime I have expanded this with another sensor for CO2, relative humidity and temperature, see the article here.

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Retbleed

Does anyone remember Meltdown and  Spectre? These vulnerabilities were discovered in June and July 2017 and publicly documented in early 2018. As a result, countermeasures have been taken by software manufacturers for both operating systems and applications, some of which also lead to reduced performance.

As reported on https://www.ncsc.admin.ch/retbleed-en, researchers of the ETH Zürich now discovered a vulnerability in one of the counter measures – retpoline – affecting CPUs by Intel and AMD which got the name “Retbleed” (CVE-2022-29900, CVE-2022-29901). Also see the description at https://comsec.ethz.ch/research/microarch/retbleed/.

Fast SSD with NVMe

NVMe is the abbreviation for “Non Volatile Memory Express” and describes a standard for connecting SSDs via PCI Express. With SATA the speed is limited to 600 MB/s. In addition, AHCI (Advanced Host Controller Interface) used by SATA was primarily developed for hard drives and limits the possible I/O operations per second (IOPS). With NVMe both have been improved – PCI Express enables significantly higher transfer rates of up to 32 GBit/s or 4 GB/s via PCIe 4x and more than 500000 IOPS.

After one of the SSDs in my “retro PC” started reporting checksum errors I installed an NVMe drive with a PCIe adapter card for M.2 as a replacement.

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