Sunday, May 17, 2015

ZFS on Linux - ignore data errors when sending snapshots

This applies to the native implementation of ZFS for Linux (see http://zfsonlinux.org/)

The Issue:

A zpool experienced data-corruption and you want to save your pool's data by sending it to another working pool via zfs send/receive.
Sadly, zfs send will abort when it detects errors on the pool (CKSUM, READ).

The solution:

Luckily, the devs of ZFS on Linux (ZoL) added a tuneable to allow zfs send to continue in such a case. (See https://github.com/zfsonlinux/zfs/issues/3422)

To sum it up: simply set the tunable "zfs_send_corrupt_data" for the zfs kernel module:

on the fly:
echo 1 > /sys/module/zfs/parameters/zfs_send_corrupt_data

for permanent use, create file "/etc/modprobe.d/zfs.conf" with this content:
options zfs zfs_send_corrupt_data=1

Monday, February 16, 2015

Set default properties for java on the commandline

If you need to add specific options to an existing java-environment, you can set those on the commandline. The java interpreter will pick up any options set for the environment-variable "_JAVA_OPTIONS" and add those to all other options that is is started with.
So if you have an existing start-script, just ensure that you set that environment-vaiable before you start it:

Here's an example for setting a default HTTP-proxy.

Windows:

#> set _JAVA_OPTIONS=-Dhttp.proxyHost=127.0.0.1 -Dhttp.proxyPort=8080
#> java -jar someprog.jar

Linux/MacOS:

#> export _JAVA_OPTIONS="-Dhttp.proxyHost=127.0.0.1 -Dhttp.proxyPort=8080"
#> java -jar someprog.jar

Saturday, July 19, 2014

Setting up a git-friendly shell-environment on Mac OS Mavericks

Shell colors (ls)

edit your ~/.bash_profile file:
export CLICOLOR=1
export LSCOLORS=ExGxBxDxCxEgEdxbxgxcxd

git colors

edit your ~/.gitconfig file:
[color]
    branch = auto
    diff = auto
    status = auto
[color "branch"]
    current = yellow reverse
    local = yellow
    remote = green
[color "diff"]
    meta = yellow bold
    frag = magenta bold
    old = red bold
    new = green bold
[color "status"]
    added = yellow
    changed = green
    untracked = cyan
git autocompletion and status in bash-prompt

edit your ~/.bash_profile file:
source /Applications/Xcode.app/Contents/Developer/usr/share/git-core/git-completion.bash
source /Applications/Xcode.app/Contents/Developer/usr/share/git-core/git-prompt.sh
GIT_PS1_SHOWDIRTYSTATE=true
export PS1='\u@\h:\w$(__git_ps1)$ '

Saturday, February 22, 2014

When files don't show up in the Mac OS finder

... then it's likely that the files have the "hidden" attribute set.
Sounds trivial really, but it did leave me stomped a bit today. Files showed up fine in the terminal when I copied them, and also Forklift showed them (turns out it only did because I had it set to also show hidden files). Anyway, finder of course didn't show the files at all.

To remove the hidden attribute, type:
chflags -R nohidden <files>

to check which extended attributes are set:
ls -lO

Friday, January 17, 2014

Guild Wars 2 Mac OS:Trading Post not working

Problem:

Some users of the Guild Wars 2 client for Mac OS might have experienced the in-app trading-post not working.
This seems to be caused by remaining wine/etc. processes that are launched by the Windows Emulation-Layers that come with the Mac Client. It seems like not all processes are killed/updated when you stop and relaunch the game. A more detailed explanation can be found on the official boards here:
https://forum-en.guildwars2.com/forum/support/bugs/Mac-Beta-Trading-Post-Issues/first#post3156901

Solution:

Exit GW2, then check the process viewer for the following running processes and kill them:

– wineserver
– CVMCompiler
– cookied
– (two instances of) Guild Wars 2

Not neccessarily all of them might be running. In my case, only cookied seemed to have been "left over".

Saturday, December 28, 2013

How to Disable SSL Ciphers in Google Chrome

What should be disabled?
RC4. All the way. RC4 should be considered unsafe. So it's best to include all IDs that contain RC4.

Most browsers still have these ciphers enabled - and certain sites (including some of Google's services) are still using these.

But usually, HTTPS-enabled sites also support other ciphers, which are considered safe by current standards. So it's only a matter of disabling certain ciphers. To do this for chrome, you need to pass a specific command-line argument:

--cipher-suite-blacklist=0x0004,0x0005,0xc011,0xc007

The list of IDs can be taken from here:

The following URL can be used to test your browser's current setting:

The IDs above were ok for me using Chrome (31.0.1650.63) on Mac OS. You might need different IDs depending on your OS and browser in use.

Sunday, February 12, 2012

Demo gegen ACTA in Nürnberg

Gestern habe ich mit Freunden an der Anti-ACTA Demo in Nürnberg teilgenommen. Auch wenn der Sound der Redner-Anlage leider zu schwach war war es trotzdem ein tolles Erlebnis zu sehen, daß so viele Menschen trotz der Kälte auf die Straße gegangen sind - und die Stimmung war super.

Was mich am meisten überrascht hat war dass ich sehr viele junge Teilnehmer gesehen habe. Oftmals Schüler. Kommt selten vor dass ich mit eher alt fühle - aber auf einer Demo war das wirklich unerwartet :)
Es stimmt mich sehr positiv zu sehen, daß die junge Generation (zu der ich mich jetzt wohl eher nicht mehr zählen kann) solch ein Interesse und politisches Engagement an den Tag legt was diese Themen betrifft.

Danke an die Organisatoren und allen die dabei waren! Laßt den Protest nicht abflauen! Es gibt noch viel zu tun und es werden sicher viele weitere Schlachten zu schlagen sein, um unsere Grundrechte zu verteidigen.

video