Mac OS X virtual IP configuration

To create a virtual IP on mac OS X, the command to be used is the following one, for example on the wifi interface :

sudo ifconfig en1 alias xx.xx.xx.xx/zz up when xx.xx.xx.xx is the expected IP address and zz the netmask

to remove the virtual interface replace alias by -alias option.

 

Customizing PirateBox configuration

After installing the piratebox, it’s nice to customize it a little bit… There are many reason for this, the first one, in my point of view is to have a more understandable SSID name depend on your country… Here are the list of the step of the customizations I made on myne.

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TP-Link MR3040, autonomy test

As promise, I’m looking for MR-3040 information about autonomy. This device is really interesting as it provides an internal battery to power the device on. The question was, how many time can we use it, is the autonomy good enough to have a real mobile device you don’t have to care about autonomy when bring out to public !

The first thing is to reload the battery, from 0 to 100% it takes 3:10 using the given equipment.  The next thing is to empty the battery by just doing nothing else than switch it on, as a result, the MR-3040 ran during 7hours. This is a really good result as it means that we can bring it out most of one day (or night).

The last step is to empty the battery transferring file from & to to mr3040, in this scenario, the battery autonomy should be smaller but the result is an autonomy of 5 full hours with a transfer rate about 1.5MB/s. I was expecting a shorter time so it is a good news.

The main issue I can raised after this test is the coverage area of these kind of devices (MR3040 or MR3020) really limited to a some meters and really blocked by rock walls. This is limiting the share with the neighborhood capability. It makes it more recommended to have a share into a room.

Installation of a piratebox on T-Link MR3040

I just received the TL-MR3040 wifi portable access by T-link. This little box is really like the mr3020 i had for my piratebox with the main advantage of having and internal battery making the piratebox mobile for a small price ! For actually 38€ (but you may found it at lower price) it is an interesting and compact solution to bring you piratebox out.

I’ll try in the next part of this article to detail the installation process as friendly as possible. Never forget that this kind of operations are not always easy and may damage your device. Do it at your own risk.

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Nmon cpu_summ vs cpu_all in a SMT environment

In a SMT CPU you have real primary core and SMT core, all can have process allocated to them but the performance of the primary logical processor compared to the SMT one are not equivalent. Usually the SMT power is about 20-30% of the primary one.

This impact the way the performance is measured

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Network performance measurement script

I regularly have to test some network products like routers or homeplug devices and most of the time, I like to test the performance of that product. I’m doing it generally a couple of time and the result can vary test after test and I did not had a good, simple and basic tool to use to measure this variation.

So, after having think to it for long months, I finally started to write some bash lines to get this tool and start to get measures…

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Oracle DB performance over low latency networks

Here is an interesting article on the impact of the latency on some usual Oracle SQL statement over Local, LAN and WAN networks.

http://markbairden.blogspot.fr/2012/03/database-performance-measuring-effects.html

Wan latency uses is 12ms which is small for this type of connection. Impact is huge with a factor of 10. To be taken into account in your designs !

Thank you Mark for this article !

New low consumption Atom devices

Not really a news, but an interesting update on two new devices sold since march 4th, Atom family have, at least, two new Core, the first one is the N2650, the second one the N2850, they are two dual core, 4 thread CPU for netbook with a really low TDP.

The N2850 offers a 2GHz system with a 10W TDP, the N2650 offers a 1.7GHz system with a 3.6W TDP.

This has to be compared with my current reference (making no sens for you … but …) the D525 offering 1.8GHz for 13W. More over the IGP has been push from 400MHz to 640MHz on the N2850.

This configuration sound really interesting to build small and fanless machine… now we need to see the first box including these chips.

See Atom family on wikipedia : http://fr.wikipedia.org/wiki/Intel_Atom