Posts from 2014-10

Building 19" Desk Addons

For my home office, I needed a way to organize my cables, equipment and switches efficiently. The way I decided to go was to attach the equipment to my desk. In a first step, I created a rack to be attached below the back side of the desk. It served...

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Counting bits set to 1 in bytes with Python / Popcount or Hamming Weight

I want to run popcount on a large set of 144-byte-long bytearrays. Doing so in Python can be a pita! First, I was using the naive approach with bin(b).count('1') but it was very slow. I did some research on the internet for faster algorithms and I found some. But running...

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HDD Spindown on Arch Linux

From hdparm's man page on the CLI parameter -S:

Put the drive into idle (low-power) mode, and also set the standby (spindown) timeout for the drive. This timeout value is used by the drive to determine how long to wait (with no disk activity) before turning off the spindle motor to...

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Connecting to Samba shares on Linux / One-way Sync

Using Samba (or SMB) shares on Linux is not difficult but you should know some tricks. First of all, you can use smbclient to probe your Samba-Server and try to connect to it. You can then mount an SMB-share locally.
In addition, I wrote a tool to synchronize a local directory with...

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Samsung SyncMaster 971p

Der SyncMaster 971P verfügt über ein hochwertiges PVA-Panel, das mit einem sehr hohen dyn. Kontrastwert (4.000:1), einem sehr hohen Betrachtungswinkel von 178°/178° (h/v) und schnellen 6 Millisekunden (G/G) Reaktionszeit aufwarten kann. Das elegante Design verleiht dem SyncMaster 971P der asymmetrische Dreigelenkfuß mit Pivotfunktion, gepaart mit dem versteckten Kabelführungssystem und dem...

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Dell PowerEdge T20 with Xeon E3-1225v3 CPU

The Dell PowerEdge T20 is a entry-level server from Dell. Being available since 01.2014 the price for those machines dropped quite rapidly in 06.2014 and now end users buy this machine to use it as a cheap desktop computer or workstation. The version with the Intel Xeon CPU 1225v3 is...

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Intel Gigabit ET Dual Port Server Adapter

Details about how a recent Linux sees the card: Intel Gigabit ET Dual Port Server Adapter on Arch Linux (Kernel v3.16)

NIC Bonding on Arch Linux

Simple bonding setup as described in the Arch Wiki:

sudo pacman -Sy ifenslave
cp /etc/netctl/examples/bonding /etc/netctl/bonding
vim /etc/netctl/bonding
# -------- content: ----------
Description="Bonded...

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First Tests with UDOO Quad

Serial Communication from UDOO to builtin Arduino Due

http://www.udoo.org/forum/viewtopic.php?p=5631#p5631

stty -F /dev/ttymxc3 cs8 115200 ignbrk -brkint -icrnl -imaxbel -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke noflsh -ixon -crtscts

Specs for the UDOO Quad

Source: http://elinux.org/UDOO#UDOO_Quad

Freescale i.MX6Quad, 4 x ARM® Cortex™-A9 core @ 1GHz with ARMv7A instruction set
GPU...

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Improving the Speed of Software Raid on Linux (Read/Write/Resync)

Speeding up the write access of a RAID array

echo 32768 > /sys/block/md0/md/stripe_cache_size

Source: Stackoverflow

Speeding up RAID1 array rebuild

With

echo 50000 > /proc/sys/dev/raid/speed_limit_min
echo 200000 > /proc/sys/dev/raid/speed_limit_max

the resync speed went from 1M/sec to about 25M/sec:

cat /proc/mdstat

Personalities : [raid1]
md1 : active raid1 sdb3[0] sda3[1]
    ...

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Using Nintendo's Bluetooth keyboard from "Learn With Pokémon: Typing Adventure (DS)" with other devices

This is simply a Bluetooth compatible keyboard.

Pairing with a PC / Tablet

  1. Switch the keyboard off.
  2. Enable Bluetooth on your PC or tablet and search for bluetooth devices.
  3. Press and hold the [FN] button of the keyboard.
  4. Switch on the keyboard.
  5. Select the keyboard on your PC or tablet and wait for a request to...

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