Showing posts from 2013

Stripped LVM (RAID 0) performance on a NAS system

Now I am setting up a new NAS and to be able to decide if I should use Stripped LVM I did some measurements. Stripped LVM means the the data volume is spread across 2 physical disks and data reads and writes are executed in parallel to the two disks, so in theory this will duplicate the disks speed. However stripping has one disadvantage that if one of the disks fails then all data is lost, while with normal volumes, there are chances that from the functional disk it is possible to restore the data. The NAS has a Gigabit Ethernet LAN connection so in theory 125 MBytes/sec speeds can be achieved.

To do the tests I have set up two 200 GByte logical volumes on the LVM containing two 4 Tbytes physical disks, one stripped across the two disks and the other without stripping. First I measured the speed within the NAS, using the linux DD command:

On the normal volume:

>dd if=/dev/zero of=/media/data/Adatok/test bs=1M count=2000      2000+0 records in
2000+0 records out
2097152000 bytes (2.1 …

Speeding up NTFS file system access on Linux with a Windows virtual machine

Summary:Ntfs-3g is not performing well, here are some measurements and a complicated way to have faster NTFS filesystem access on Linux.

Disclaimer: These tests were done on an Ubuntu 10.4 LTS installation, with the latest sw versions included in this Ubuntu distribution, but on the ntfs-3g site there are more recent versions of that ntfs-3g.

I wanted to do a backup of my Linux based NAS, to an NTFS formatted hard drive, which meant to copy around 4 TByte of data.

As the first step I built the disk into the NAS machine over a SATA connection and measured the drive speed:

>sudo hdparm -t /dev/sdf

 Timing buffered disk reads:  432 MB in  3.01 seconds = 143.62 MB/sec

This looks good, this means, 4 TB/143MB ~ 7 hours of copy time.

Next I mounted the already formatted drive and did a copy test:

>sudo mount -t auto /dev/sdf2 /media/windows/
>dd if=/dev/zero of=/media/windows/test bs=512 count=390625
390625+0 records in
390625+0 records out
200000000 bytes (200 MB) copied, 94.6419 …

Installing Ubuntu server 12.04 LTS from pendrive on an old PC to create a NAS

I have a pretty old PC from 2003 which I have been using for some time as a NAS. It is a standard desktop PC (self built), but it has 8 IDE hard drives ranging from 200 Gbyte up to 500 Gbyte. The total capacity of the drives is around 2 T and I just decided to give a refresh to the system to back up my digital videos to it.

I have been using FreeNAS 7.2, which is pretty nice, but it is BSD based and as I have more experience with linux and especially with Ubuntu Server so I decided to upgrade to that one.

Here comes a short guide on how to setup Ubuntu Server on a machine to work as a simple NAS.

Installing Ubuntu Server from pendrive (Flash memory)
Today this should be a strait forward thing, you take the installation ISO image, with some tool you copy it to a pendrive you plug it into the machine and install it, but in my case I run into plenty of problems. By the end I have solved all of them, but here is a list of how to solve them one by one.

1) Copy the ISO to a pendrive: I have…

Cleaning file names in XBMC before scrapping

XBMC is an excellent media center for use on a lot of different platforms. Beside the various playback possibilities it has a very good scrapping and library functionality, which means, that based on the video file name, it can download DVD cover, director, actors and all kind of useful information. When using the program you can select the movie based on all this nicely presented information and pictures and not only the equally looking file names.

During scrapping - when the data is collected from different movie databases on the internet (like IMDB) -  XBMC first tries to figure out the movie title from the file name and then calls a plugin, which then retrieves the data from the internet.

In this post I will discuss, that how the file name to movie title conversion is working. The here mentioned  cleandatetime and cleanstrings can be customized in advancedsettings.xml, so you are able to finetune the process.
The file name is matched against thecleandatetime; a regular expression s…

Difference between W25 SW and Netgear WNR2000v2 SW

Recently I bought some used Netgear 300 M routers for a very affordable price and I have checked a bit of the internal structure of the SW that came with that router.

It was very interesting to look at the architecture of this software as it was quite different from the one found on W25.

The first positive surprise is that Netgear provides the complete build environment for the router with a lot of source codes and instructions on how to build the firmware. I have actually not tried to build the firmware, but when checking the details of the operation I could find all the relevant source files. As far I know Ericsson has never released the source code of the W25, probably violating the GNU licence of lot of its components.

On the other side the structure of the W25 is much nicer, it is like a mini linux machine keeping most of the conventions of the desktop linux operating systems. The configuration is stored in the /etc directory, the standard tools to set up the network and other p…

Android phone not syncing with Google account

Recently I run two times into the above mentioned problem, and the reasons were obvious, so I share the common reasons with you:

1) Adding new calendar event on the phone

When you add a new calendar event on your phone, according to the defaults settings it is added to the local calendar on your phone which is not synchronized to your Google  account. Once you have done this, you can not correct it, you have to add it again to your Google calendar, but to avoid this mistake you should always check that the appointment is added to to correct calendar.

2) The Google account not syncing at all

In this case none of the mail, calendar or contacts is syncing, you can go to your accounts, you see that synchronization is enabled for all of them, but the latest synchronization is some days old, and even if you ask for an immediate synchronization nothing happens. The reason for this in my case was that the available free space went down, and I had already a notification icon. It was a bit stran…