Category Archives: Technology

Adding a disk to your logical volumes

Post migrated from my old site:

I found this information quite useful:
http://www.linuxnetadmin.com/2008/01/how-to-add-disk-space-with-lvm-on-linux.html
https://ext4.wiki.kernel.org/index.php/Frequently_Asked_Questions

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Firefox fix for Fedora 12

Post migrated from my old site:

If your Firefox automatically starts offline after updating NetworkManager, you can solve this by entering

about:config

in the Firefox url bar and modify

toolkit.networkmanager.disable

to true.

Fedora – Installing VirtualBox with Yum

Post migrated from my old site:

Instructions to install VirtualBox (http://www.virtualbox.org) with Yum on Fedora can be found here:
http://www.virtualbox.org/wiki/Linux_Downloads

Debian 5 – Using the internal editor of Midnight Commander (mc)

Post migrated from my old site:

By default in Debian 5 mc is configuration to use nano which somehow I cannot get used to.
To fix this, go into the menu by pressing F9, Options > Configuration, Use internal edit.

Adding a Samba user

Post migrated from my old site:

Samba can be used to share folders with Windows systems.

To add a user to Samba, use

smbpasswd -a <username>

Setting up an encrypted RAID 5 on Ubuntu 10.10

Post migrated from my old site:

Recently I started on configuring an encrypted RAID 5 on Ubuntu 10.10 Server. These were the steps I took:

First, install the required packages:

sudo apt-get install mdadm gddrescue cryptsetup lvm2

I used fdisk to partition each disk as a “Linux raid autodetect” partition.

sudo fdisk /dev/sdb

for each device (in my case /dev/sdb /dev/sdc /dev/sdd and /dev/sde). First use option “n” to add a partition, option “t”to change it to type “fd” and “w” to write the changes to disk.

Next step is to create the RAID5 device:

sudo mdadm /dev/md0 --create -n 4 -l 5 -z 244198584 -c 256 /dev/sd{b..e}1

244198584 is the number of kilobyte of a single disk obtained with:

sudo hdparm -I /dev/sdb

Once it has been created, check its status by

sudo cat /proc/mdstat

and

sudo mdadm --detail /dev/md0

Wait until the status reports that the RAID has been fully build.

Next step is to create a physical volume by:

sudo pvcreate /dev/md0

To create a volume group, use:

sudo vgcreate rawlargevg /dev/md0

To create a logical volume, use:

sudo lvcreate -n rawsharelv -L 732585984k rawlargevg

Obtain the size by using:

sudo vgs --units k

To randomize the disk content use:

sudo ddrescue /dev/urandom /dev/rawlargevg/rawsharelv urandomminglog

This might take a long time, after it is done, start setting up the encrypted volume:

sudo cryptsetup -c aes-cbc-essiv:sha256 -y -s 256 luksFormat /dev/rawlargevg/rawsharelv

Next step is to open it:

sudo cryptsetup luksOpen /dev/rawlargevg/rawsharelv encsharedev

And format it:

sudo mkfs.ext4 -m 0 /dev/mapper/encsharedev

After it is done formatting, create a mounting directory:

sudo mkdir /srv/raid

Now edit the /etc/crypttab file to include:

encsharedev /dev/rawlargevg/rawsharelv none luks

And edit /etc/fstab to include:

/dev/mapper/encsharedev /srv/raid ext4 rw 0 0

Reboot and done you are with setting up your encrypted RAID.

References to pages I used:

User and group Apache is running under Ubuntu 10.10

Post migrated from my old site:

To find out the user and group Apache is running under Ubuntu 10.10, look at:

/etc/apache2/envvars

Look at the lines:

export APACHE_RUN_USER
export APACHE_RUN_GROUP

by default it is www-data.

Installing SugarCRM 6.0.3 on Ubuntu 10.10 Server

Post migrated from my old site:

I have been trying to set up SugarCRM 6.0.3 on a Ubuntu 10.10 VM.

This link has been very helpful:
http://g00t.com/?p=358

Another useful link is:
http://www.howtoforge.com/installing-sugarcrm-community-edition-on-ubuntu-8.10

Canon i-Sensys MF8030Cn on Ubuntu 10.10

Post migrated from my old site:

Driver for Linux can be found here: http://software.canon-europe.com/software/0040355.asp?model=

Some more help might be found here: https://help.ubuntu.com/community/CanonCaptDrv190

MPlayer and MEncoder to the rescue!

For those of you that have not discovered MPlayer and MEncoder yet. If you find yourself trying to combine dozens of codecs, converters, etc. and nothing works, to convert a movie, try MPlayer and/or MEncoder. Every time I have problems converting MEncoder proves to be the solution.
http://www.mplayerhq.hu