Playing with Drobo (updated !)

I did buy a Drobo for my server. 
Here a kind of review and my discoveries.

Of course the main purpose is to connect Drobo to my server, so I'm planning to use it only for Linux.
The goal is to end up with at least  a couple of Terabyte of space, possibly more in the future.

Compile ZeroMQ as static library

On some environment can be useful to have ZeroMq as static library rather than a dynamic one.
In order to create a static ZeroMQ library, follow these steps.

To do so, under ubuntu :

1. sudo apt-get install build-essential
2. sudo apt-get install libtool
3. sudo apt-get install automake
4. sudo apt-get install autoconf
5. sudo apt-get install uuid-dev
6. Download the tarball for the libsodium from the Libsodium website
7. Extract the tarball in a directory
8. go in the directory
9. ./configure --enable-static --disable-shared
10. make
11. sudo make install
12. Download the tarball from the ZeroMQ website
13. extract the tarball in a directory
14. go in the directory
15. ./configure --enable-static --disable-shared
16. make
17. sudo make install

At this point is better to close all the terminals and re-open them.

On some systems is better to run :
sudo ldconfig to update the system library cache, otherwise it is requested a reboot of the machine.

Install Czmq

In order to bind the library with the C language is necessary to compile the library Czmq

1.  git clone https://github.com/zeromq/czmq
2.  cd czmq
3.  ./autogen.sh
4.  ./configure --enable-static --disable-shared
5.  make
6.  sudo make install
7.  sudo ldconfig

5V Solar Power Supply - testing results

As described in the 5V Solar Power Supply - testing system article, here some results after running tests for a while.

First of all, I did connected the data logger to the battery terminal and let it run for few days, with the load connected, drawing around 350mA.
Here a graph, starting with the battery charged.
Once the battery was depleted, with the load connected there is no way to have it recharged enough.
The weather was good at least for the last two days, so plenty of sun, but even with the 3W solar panel the battery was unable to be charged enough.

This indicates anyway the need to disconnect the DC/DC converter in order to have the battery charged.

Developer tips - CentOS 7 notes

Just a post with some notes to remember what to do when encountering some recurring problems after installing CentOS on a vm for tests.

The scenario : installation CentOS 7 64 bit on VirtualBox (on a Mac)

1. yum update
   After installation yum update is not working
   Yum returns an error like : "Cannot find a valid baseurl for repo".
   
   Could be a connection problem and a configuration problem.
   Let try to issue the command : sudo dhclient
   
   If it solve the problem (i.e. if Yum works as expected) edit the file /etc/sysconfig/network-scripts/ifcfg-enp0s3.
   Change the line ONBOOT=No in ONBOOT=Yes.
   Save.
   Reboot
   
   Is possible sudo command will not work (see sudoers below)
2. Gnome GUI
   Installation of the iso (tested on DVD.iso) does not have a GUI.
   To install Gnome :
1. yum update
2. yum groupinstall "GNOME Desktop" "Graphical Administration Tools"
3. ln -sf /lib/systemd/system/runlevel5.target /etc/systemd/system/default.target
4. reboot
3. Sudoers
   Add the user in the sudoers list.
   Assuming to be logged as user, go in the root account using for example ssh.
1. ssh root@localhost
2. If the first time type Yes to the request to add the localhost key.
   Then enter the root password
3. Use the command visudo to edit the sudoers list.
   Locate the root and add below the user with the same levels of access
4. save

Developer tips - loading iOS apps directly

Sometime is quite useful to be able to load an iOS app under development on a phone directly, without passing for the Apple store.

On the latest version of iTune it was removed the possibility to load directly an app.

If you have a Mac with  macOS High Sierra Version 10.13.3 it is very possible your iTune will not allow you to load an app directly to an iPhone connected via USB.

Developer tips - Visual Studio - workarounds

Ok, let me start with I didn't choose to use Visual Studio !!  😛
But sometime is the pain that choose you.

In my case I'm using Visual Studio 7.4 on a Mac in order to develop apps Android and iOS in C# (old Xamarin).

This article contains some tips I discovered that can be useful if somebody else has the pain to use 'that'.
Of course this article is working in progress, expect updates.