Aug 072015
 

Yesterday, my SanDisk Ultra II 240 GB solid state drive – which hosts my Arch Linux system partition – showed a lot of ata errors (in the kernel message output dmesg). Rebooting was not possible, the system startup halted – again showing some ata failures. Very annoying!!! I was very happy with the performance of this SSD so far. But how reliable is it? Anyway, I only had my system installation on there so not much valuable data – but setting the system up once more would be annoying enough. (Next time, I will set up my system as described in my blog post RAID1 with SSD and HDD!)

Aug 032015
 

Inspired by a couple of blog posts (see resources section) I put together my own collection of software to operate a USBTMC to Ethernet Gateway on a Raspberry Pi (1 or 2):

https://github.com/pklaus/rpi-usbtmc-gateway

Installation

I use Arch Linux ARM and the shell scripts are made for Arch. It shouldn’t be too hard to port it to Raspbian though.

The installation starts with a one-liner:

bash -c "$(curl -fsSL https://raw.githubusercontent.com/pklaus/rpi-usbtmc-gateway/master/rpi/00_leverage.sh)"

Then follow the instructions.

Resources

Jul 312015
 
vim /etc/pacman.conf
#! enable multilib
sudo pacman -S lib32-glibc
cd ~/AUR-installations/AUR-Mirror/brother-hl2250dn/
makepkg -s
sudo pacman -U brother-hl2250dn-2.0.4_2-4-x86_64.pkg.tar.xz

When setting it up with CUPS according to the Arch Wiki Page on this printer, choose the connection string lpd://Brother-HL-2250DN/BINARY_P1 (where you adjust Brother-HL-2250DN to the hostname of your printer and make sure its hostname can be resolved to its IP via your local DNS).

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Jul 202015
 

Default login data:

Most important specs:

  • SIM Format: Micro Sim
  • Antenna Connectors: 2x TS9

Specs (German):

  • 150Mbit/s Cat.4 LTE/4G/3G/HSPA+2G
  • Dual-Band-WLAN 2,4GHz/5GHz
  • WLAN 802.11 b/g/n, 2×2 MIMO
  • Multiple SSID/Gast-WLAN-Unterstützung
  • LCD-Farbdisplay
  • WiFi Protected Setup (WPS)
  • 4,5-cm-LCD-Farbdisplay
  • Erfassung der Datennutzung
  • 4G/3G-Netzwerk-Info/Status
  • WLAN Netzwerk-Info/Status
  • Akkulaufzeit
  • Austauschbarer Lithium-Ionen-Akku (2000 mAh)
  • Maße: 109,9 mm (L) x 68,9 mm (B) x 14,6 mm (H)
  • Gewicht: 127 g

Specs (English):

Network Technology

4G LTE: 700/900/1800/2100/2600 MHz, 2x2 MIMO
3G HSPA+: 850/2100 MHz
FDD LTE Rel. 9 Category 4

Wi-Fi Features

Jul 122015
 

Using dmidecode:

dmidecode -t memory | grep 'Physical Memory Array' -A7

Using ecc_check.c:

wget -O ecc_check.c http://pastebin.com/raw.php?i=URExZi29
gcc ecc_check.c -o ecc_check
./ecc_check

Tools using EDAC:

sudo modprobe edac_core
# Kernel 3.17 will include support for all Xeon E3-12xx CPUs (such as 1225v3):
sudo modprobe ie31200_edac

Via sysfs:

ls -la /sys/devices/system/edac/mc/*

Using edac-utils:

# Install on Ubuntu/Debian:
apt-get install edac-utils
# On Arch Linux, you can get it from AUR:
# https://aur.archlinux.org/packages/edac-utils/

edac-ctl --status
edac-util --verbose --status
edac-util --verbose

Using mcelog:

apt-get install mcelog
mcelog --client

Resources

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Jun 042015
 

You can create a RAID1 spanning an SSDs and HDDs with Linux software raid. This makes sense to profit from the advantages of both technologies as much as possible. Use the --write-mostly for mdadm for HDDs to specify that they should be avoided for reads.

From the mdadm man page:

-W, --write-mostly subsequent devices listed in a --build, --create, or --add command will be flagged as ‘write-mostly’. This is valid for RAID1 only and means that the ‘md’ driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.

May 282015
 

If you get an error message like

Traceback (most recent call last):
  File "./append_to_hdf5.py", line 81, in <module>
    main()
  File "./append_to_hdf5.py", line 63, in main
    store.append('df', df, format='t', complib=None)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 904, in append
    **kwargs)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 1260, in _write_to_group
    s.write(obj=value, append=append, complib=complib, **kwargs)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 3753, in write
    **kwargs)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 3434, in create_axes
    raise e
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 3429, in create_axes
    **kwargs)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 1848, in set_atom
    encoding)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 1892, in set_atom_string
    eci = existing_col.validate_col(itemsize)
  File "/home/philipp/.pyvenv/playground-3.4/lib/python3.4/site-packages/pandas/io/pytables.py", line 1560, in validate_col
    "these columns" % (itemsize, self.cname, c.itemsize))
ValueError: Trying to store a string with len [42] in [values_block_0] column but this column has a limit of [18]!
Consider using min_itemsize to preset the sizes on these columns

Then you should add min_itemsize=200 to your call of store.append().

May 232015
 

Model No: 22809/20131219AKE

Hardware details as seen by Linux 3.17

The jumper positions are stupid…

Pin 1 is near to the internal SATA ports, pin 3 is near the PCIe slot. You can also follow the traces on the black PCB.

Fix for optical drives (as found here):

UPDATE: Unter Linux braucht man für optische Laufwerke an diesem Controller den Kernelparameter: libata.atapi_passthru16=0

head /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="quiet pci=assign-busses console=tty0 console=ttyS1,115200n8 libata.atapi_passthru16=0"
#GRUB_CMDLINE_LINUX_DEFAULT="quiet pci=assign-busses console=tty0 console=ttyS1,115200n8"
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Apr 282015
 

Commands you enter on the Linux command line are valuable. They are part of your computer knowledge, you should remember them. If you don’t, [Ctrl]-[r] will come to your rescue to search your Bash history for commands you entered in the past. But your Bash is forgetful by default. Only the very last commands will be kept in the Bash history file ~/.bash_history. If you want it to remember more of your previously entered commands including preciously crafted arguments and parameters, add these lines to your ~/.bash_profile:

Apr 262015
 

Hackaday Finding a Cheaper USB to Serial Chip

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