When installing software from non-official repositories in Debian-based distributions, you might come across “key problems”, such as:
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY <key>
When it appears, you might scratch your head for quite some time.
There is a simple way of dealing with those. However, as I recently experienced while upgrading a machine, most tutorials are incomplete or even sometimes totally misleading.
First, let’s see what these keys are for.
When installing software from non-official repositories, Linux needs to download packages from those external sources. However, hackers may introduce malware inside the files that are on the servers of those external sources. This type of hack is not an easy one, since web administrators are watching those sites closely. However, when it succeeds, the attackers can automatically distribute their malware to a lot of computers at once. Consequently, everything should be put in place to avoid spreading Trojan horses this way.
This is why any file that can be downloaded is signed digitally by the actual provider of the source. If a hacker alters a file, the digital signature no longer matches the content of the file anymore. This way, your Linux distribution makes sure that anything it downloads is an unaltered original file as originally published by the source.
To verify the signature, it only needs the public key of the source. And that is why your distribution needs to keep a list of public keys of all the non-official sources.
The apt-key way (deprecated in Ubuntu 22)
Previously, one could import keys using a tool called “apt-key”. Such way is still generally mentioned in many tutorials, in the form:
Obviously, this means that the supply chain has to grow accordingly, which is not always a given. And electronics are not the only ones suffering from supply chain problems: plastics are also in a strange condition right now.
The “work from home” drill
One of the first reasons for the shortage is a higher demand from consumers. With the pandemic and everyone switching to remote working last year, people had to buy extra computers (at least one for every member of the family) or upgrade existing ones (think about a better camera, a better processor or graphics card to deal with the video live streams, a larger screen on your desk at home since it has become your semi-permanent office, etc.).
This sudden demand created a spike in an already congested industry, hence a shortage. The problem is that such a spike should be only temporary, but it looks like the situation is not going to be resolved anytime soon. What is going on?
Remember the toilet paper shortages? Well, that’s pretty much what is happening with the electronics industry right now. Because people started being aware of the shortage and the potential for it to become long term, they have acted exactly as they did with toilet paper. Buy more. As soon as possible. Before it is too late.
So the initial hit on the demand is also worsened by panic buying. Of course, buying an extra computer is not as easy for many people as buying toilet paper, due to the price difference. So while the effect is felt within days for toilet paper, the time frame is counted in months for electronics.
The car industry
The car industry is one of the most demanding in terms of electronics: our cars are getting stuffed more and more with those chips and gadgets, and it is getting to a point where the car industry is hit very badly by the shortage. It is currently causing very heavy losses in sales in that sector. Back to the first chart of this post above, we can see that batteries for electric-powered vehicles is mainly responsible for the demand to jump almost exponentially. Any shortage in those immediately results in slower production.
Accumulation of incidents
There have also been two major fires in the industry (one in Japan, another one in Taiwan), which have worsened the shortage, especially for memory chips.
As I warned a year ago on my blog at the beginning of the pandemic, Covid also disrupts supply chains since productivity is impacted – when the industries don’t close altogether. People needing to stay at home at the first sign of illness, whereas before everyone was still going to work with a running nose. And of course, wearing masks, material needing disinfection, etc.
All this obviously slows down existing systems. And again, in a “just-in-time” production mode with rising demand, this can only cause shortages.
Raw material shortage
As we all know, our planet is not infinite. With such a growth in demand, there must mathematically be a point when this never-ending growing trend goes beyond the total resources of the planet.
Along with silicon, some rare metals are getting scarce, if not already at the point of exhaustion. Other metals and rare-earth elements will follow, without any doubt. There would be a lot to talk about on this topic, but I’m keeping it short for now. Recycling those rare metals is typically a very big challenge – some of them in electronic components can actually never be recycled since it would need going to the atomic level.
And the shortage for some metals is not so far away. Just look at “other industrial metals” in the following chart, there is a chance you’ll see the shortage of some of them in your lifetime. And what then?
The current shortage has many causes. Some of them may be temporary, but others will undoubtedly be felt on the long term. Hopefully, as the price of the rarest materials increase, alternative technological solutions will enable us to replace rare materials with more common ones. Or maybe we’ll find this missing Germanium or Palladium on the Moon or Mars…
The post title may be blunt. But I think after reading this article, you will never use the type “char” in Java ever again.
The origin of type “char”
At the beginning, everything was ASCII, and every character on a computer could be encoded with 7 bits. While this is fine for most English texts and can also suit most European languages if you strip the accents, it definitely has its limitations. So the extended character table came, bringing a full new range of characters to ASCII, including the infamous character 255, which looks like a space, but is not a space. And code pages were defining how to show any character between 128 and 255, to allow for different scripts and languages to be printed.
Then, Unicode brought this to a brand new level by encoding characters on… 16 bits. This is about the time when Java came out in the mid-1990s. Thus, Java designers made the decision to encode Strings with characters encoded on 16 bits. All Java char has always been and is still encoded with 16 bits.
However, when integrating large numbers of characters, especially ideograms, the Unicode team understood 16 bits were not enough. So they added more bits and notified everyone: “starting now, we can encode a character with more than 16 bits”.
In order not to break compatibility with older programs, Java chars remained encoded with 16 bits. Instead of seeing a “char” as a single Unicode character, Java designers thought it best to keep the 16 bits encoding. They thus had to introduce the new concepts from Unicode, such as “surrogate” chars to indicate that one specific char is actually not a character, but an “extra thing”, such as an accent, which can be added to a character.
In fact, some characters can be thought of in different ways. For instance, the letter “ç” can be considered:
either as a full character on its own, this was the initial stance of Unicode,
either as the character “c” on which a cedilla “¸” is applied.
Both approaches have advantages and drawbacks. The first one is generally the one used in linguistics. Even double characters are considered “a character” in some languages, such as the double l “ll” in Spanish which is considered as a letter on its own, separate from the single letter “l”.
However, this approach is obviously very greedy with individual character unique numbers: you have to assign a number to every single possible variation of a character. For someone who is only familiar with English, this might seem like a moot point. However, Vietnamese, for instance, uses many variations of those appended “thingies”. The single letter “a”, can follow all those individual variations: aàáâãặẳẵằắăậẩẫầấạả. And this goes for all other vowels as well as some consonants. Of course, the same goes for capital letters. And this is only Vietnamese.
The second approach has good virtues when it comes to transliterating text into ASCII, for instance, since transliterating becomes a simple matter of eliminating diacritics. And of course, when typing on a keyboard, you cannot possibly have one key assigned to every single variation of every character, so the second approach is a must.
Special cases: ideograms
When considering ideograms, there are also a small number of “radicals” (roughly 200 for Chinese). Those get combined together to form the large number of ideograms we know (tens of thousands).
It would be feasible to represent any Chinese character using a representation using radicals and their position. However, it is more compact to list all possible Chinese characters and assign a number to each of them, which is what was done by Unicode.
Another interesting case is Hangul, which is used to write Korean. Every character is actually a combination of letters and represents a syllable:
So, in some cases, it is easier to assign a number to every individual components and then combine them (which happens when typing in Korean on a keyboard). There are only 24 letters (14 vowels and 10 consonants). However, the number of combinations to form a syllable is very large: it amounts to more than 11 000, although only about 3 000 of them produce correct Korean syllables.
People, especially in social media, use an increasing number of special characters, emojis, and other funny stuff, from 𝄞 to 🐻. Those have made it into Unicode, thus making it possible to write ʇxǝʇ uʍop ǝpısdn, 𝔤𝔬𝔱𝔥𝔦𝔠 𝔱𝔢𝔵𝔱, or even u̳n̳d̳e̳r̳l̳i̳n̳e̳d̳ ̳t̳e̳x̳t̳ without the need for formatting or special fonts (all the above are written without special fonts or images, those are standard Unicode characters). Every flag of the world’s countries have even made it as a single character into the Unicode norm.
This plethora of new characters which made it late into the standard are often using more than 16 bits for their encoding.
Using type “char” in Java
When using the type “char” in Java, you accept that things like diacritics or non existent characters will be thrown at you, because remember, a char is encoded with 16 bits. So, when doing “𝄞”.toCharArray() or iterating through this String’s chars, Java will throw at you two characters that don’t exist on their own:
Both those characters are illegal, and they only exist as a pair of characters.
Bottom line, when it comes to text, chars shouldn’t be used. Ever. In the end, as a Java developer, you have probably learned that, unless doing bit operations, you should never use String.getBytes(), and use chars instead. Well, with the new Unicode norms and the increasing use of characters above 0xFFFF, when it comes to Strings, using char is as bad as using byte.
Java type “char” will break your data
Consider this one:
What do you think this prints? 1? Nope. It prints 2.
Here is one of the consequences of this. Try out the following code:
This prints the following, which might have surprised you before reading this blog post:
But after reading this post, this makes sense. Sort of.
Because substring() is actually checking chars and not code points, we are actually cutting the String which is encoded this way:
\uD834 \uDD1E \u0031 \___________/ \____/ 𝄞 1
It is amazing that a technology such as Java hasn’t addressed the issue in a better way than this.
Unicode “code points”
Actually, it is a direct consequence of what was done at the Unicode level. If you tried to break down the character 𝄞 into 16 bits chunks, you wouldn’t get valid characters. But this character is correctly encoded with U+1D11E. This is called a “code point”, and every entry in the Unicode character set has its own code point.
The down side is that an individual character may have several code points.
Indeed, the character “á” can be either of these:
the Unicode letter “á” on its own, encoded with U+00E1,
the Unicode combination of the letter “a” and its diacritic “◌́”, which results in the combination of U+0061 and U+0301.
Java code points instead of char
A code point in Java is a simple “int”, which corresponds to the Unicode value assigned to the character.
So when dealing with text, you should never use “char”, but “code points” instead. Rather than
Instead of iterating on chars, iterate on code points. Whenever you want to check for upper case characters, digits or anything else, never use the char-based methods of class Character or String. Always use the code point counterparts.
Note that this code will actually fail with some Unicode characters:
for (int i = 0 ; i < string.length() ; i++) if (Character.isUpperCase(string.charAt(i))) ... do something
This will iterate through characters that are NOT characters, but Unicode “code units” which are possibly… garbage.
Inserting data into a database
Consider a simple relational table to store unique characters:
id 🔑 (primary key)
c (unique constraint)
Now imagine your java program is inserting unique characters in the column “c” of this table. If based on “char” the Java program will consider two different surrogate chars as different since their code are different, but the database will store strange things at some point since those are not valid Unicode codes. And the unique constraint will kick in, crashing your program, and possibly allowing wrong Unicode codes to be pushed into the table.
String.codePoints() (to which you can append toArray() to get an int)
iterate with String.length()
convert String into an int of code points and iterate on those
Make sure you don’t cut between a surrogate pair. Or use int of code points altogether.
replaceAll(String, String) and other replace methods using Strings
new String(char) new String(char, offset, count) String.valueOf(char)
new String(int codePoints, int offset, int count) with code points
Edit au 28/09/2021 : ajout des vues ajustées par tranches de population.
La transparence est essentielle pour construire une société de confiance. Étant moi-même toujours en doute avec les informations que je rencontre, quelle que soit leur source, je me suis posé beaucoup de questions sur la mortalité depuis le début de l’épidémie de Covid. J’ai d’ailleurs posté des compte-rendus détaillés (et moins détaillés) de ce que je trouvais sur la Covid, ainsi que d’autres informations ici, là, et là et ailleurs.
L’un des principaux problèmes qu’un citoyen lambda rencontre très vite, c’est la difficulté à évaluer des données nationales qui sont par définition des agrégats, parfois des agrégats d’agrégats… sachant que tout le monde y va de ses propres interprétations. Il me fallait donc repartir de données brutes difficilement falsifiables ou manipulables.
Quelles données ?
Par ailleurs, la comptabilisation des « morts Covid » est toujours biaisée, car comme je l’indique dans cet autre billet, on meurt le plus souvent d’une multitude de facteurs, pas seulement de la Covid (ou d’une autre maladie).
Il ne nous reste donc plus, à nous autres citoyens lambda, la mortalité « toutes causes », qui représente une réalité non biaisée : telle personne est morte à telle endroit à telle date. Or, l’INSEE fournit exactement ces données détaillées. Les données ont toujours 1 mois et demi à 2 mois de retard. Cela permet tout de même de regarder rétrospectivement ce qui s’est passé pour pouvoir anticiper ce qui va arriver. Mais surtout, cela permet de juger du degré de fiabilité de diverses sources d’informations lors des événements passés, et ainsi de se construire un indice de confiance sur telle ou telle source.
J’ai donc développé un programme pour analyser ces données et calculer des courbes de mortalité à partir de ces données brutes. J’ai également mis en place un site pour afficher les résultats, que vous pouvez consulter là (le site est chez moi, il est donc possible qu’il ne soit pas toujours disponible et qu’il donne une vue erronée au moment où je fais des mises à jour des données, une fois par mois).
Petit manuel de l’utilisateur
Quelques petites remarques sur le site :
les données proviennent directement des données brutes, filtrées (car il y a des doublons dans les fichiers de l’INSEE),
le graphe correspond à une année entière, donc les données les plus à gauche correspondent au début de l’année, et celles les plus à droite à la fin de l’année,
les différents types d’affichage sont :
absolu : c’est le nombre de morts chaque jour,
pondéré : le nombre de morts pour 1 million d’habitants, ce qui permet de comparer d’une année sur l’autre puisque la population varie d’une année sur l’autre,
étalé : c’est la moyenne glissante du nombre de morts pour 1 million d’habitants sur 10 jours, cela permet d’avoir une version « lissée » des courbes,
pondéré 70+ et étalé 70+ : mêmes vues que les précédentes, mais au lieu de pondérer par la population par année, ces vues sont pondérées par la mortalité moyenne de la population en fonction des tranches d’âges vivantes de l’année en cours, que l’on peut récupérer par exemple ici sur le site de l’INSEE.
on peut filtrer par département (ou par pays étranger) pour observer la mortalité dans une région donnée et ainsi cibler des événements locaux,
on peut également filtrer par tranches d’âges pour voir l’impact des événements en fonction des âges,
on peut filtrer avec un intervalle d’années et/ou de mois, afin de pouvoir comparer des années proches sans le « bruit » des autres années,
lorsqu’une seule année est sélectionnée (filtrage de l’année x vers la même année x), l’affichage bascule automatiquement en mortalité par tranche d’âges, pour analyser un événement en particulier de cette année-là, par exemple.
Dans un souci de transparence et pour faire marcher l’intelligence collective, je publie les sources de mes programmes en open source. Ainsi, chacun peut vérifier mon code, et même l’installer chez soi, le modifier, l’améliorer, et se faire sa propre opinion en toute indépendance.
This week-end’s project was focused around building a simple indicator on my desk that alerts me of any problem at home in real time. That way, I don’t need to regularly check things around. Well, this may sound overkill for many people. But over the years, I’ve written a program to monitor many things around me without the need to perform a regular check myself. The only thing I was missing was some real-time indicator that would alert me whenever something urgently needed my attention.
Computers. I am a computer engineer, and as such I do have a few electronic equipment around. I also monitor the temperature, humidity in and out of the apartment and also water leaks with sensors, as I have some sensitive musical instruments in my home. In the past 2 months, the temperatures here have gone up to 37 degrees Celsius several times. These measurements have helped us, without air conditioning (any form of heat pump makes things worse for the environment on the long term), to mitigate the heat. We could close everything when outside was hotter than inside, and open in the evening when the temperatures outside were coming close to the temperature inside.
Here are the temperatures my system measured for the last 5 days:
Where I came from
I already had a raspberry pi set up with a tiny monitor showing all the indicators and a big green light (or orange or red) showing the overall status. Something like this:
But this screen consumes 2.5 Watts when it is on, and only 0.15 Watt when it is off. This is a substantial difference, not even mentioning how much wear it causes the screen to be constantly on, just to show a green light!
A simple solution: use simple LEDs (which consume virtually nothing) controlled by the raspberry. So I built a first circuit to test the whole thing out:
Of course, that also works with the screen off, that’s the goal after all!
A printed circuit
I had to arrange things together on a smaller plate:
… and solder the whole thing together (yes I butchered the soldering, sorry):
That was a mess…
Buddha (you can see his legs on top of the picture) had a hard time coping with the mess, but he played his role perfectly and went into a deep meditation:
And of course I then had to use this very useful piece of equipment for the cables:
Trying it out
The first testing worked out as expected.
I just needed to print a little box for it with the 3D printer:
You might wonder why there are two alternating green lights. Actually, using a single green LED was not an option. If it was constantly on and green, then I wouldn’t be able to know if the program that controls the indicator is still running… or if it has crashed. Of course, I could make one single LED blink… but any blinking inevitably catches the eye and is bothering. On the other hand, two alternating green lights don’t catch the eye because the overall luminosity is constant, while ensuring that the program is alive.
Of course, the error state with a red light and the warning state with an orange light are blinking to make sure that my eye will instantly see it:
You might have noticed that I also have doubled those, this time it is a simple redundancy in case one of the LEDs fail (which is not very likely any time soon given how robust those LEDs are). Besides, I found the luminosity of a single LED a little bit weak, so I preferred having two LEDs with a stronger resistance and thus less strain on each individual LED.
And now I have an indicator on my desk telling me at all times that everything is ok. Or not.
Deuxième vidéo d’une série sur la blockchain. Si vous avez entendu parler de cette technologie mais que vous vous posez des tas de questions, cette série est faite pour vous !
Après avoir donné un rapide historique et les divers usages de cette technologie dans la première vidéo, on s’attaque cette fois à ce que c’est un peu plus en détail sans pour autant virer dans la technique.
Visible aussi sur youtube : https://youtu.be/Zhvq0wE8F3Q
I’ve just unmounted my drives from my Synology box, replaced by a home-brewed server. I’ll write some other article about the reasons that made me switch. Just in case you wonder, the Synology box is running fine. That’s not the point.
I took the disks from the Synology box and plugged them into a host with simple Linux distrib (in my case, Ubuntu, but that shouldn’t matter).
mount /dev/vg1000/lv /mnt
That’s it. You have the file system from your Synology box on your Linux machine. It may come handy in case your box crashed and you are waiting for a new one. In the meantime, you have access to your data.
In case you want to reuse the disks and dispose of them (WARNING: the following will destroy your data on those disks), here is how to do it.
Now check the md volumes that are available and that you didn’t create yourself (just use ls /dev/md12*). Then stop those volumes (replace md12? with the volumes you want to stop if you have additional ones on your system that you obviously don’t want to stop – they won’t stop if they are mounted anyway):
mdadm -S /dev/md12?
Empty the beginning of the related disks, for each disk replace the … by your disk letter:
dd if=/dev/zero of=/dev/sd… bs=1M count=1024
And now you can play around with partitioning etc without being bothered again by vg1000 or mdadm.
This may be a long post, but I hope to keep it entertaining for both writers and non writers. Let me know what you think!
Some history – where I come from
I’ve always loved to write. As a child, I already started writing similar stories than the ones I was reading: children stories. At the time, I was left with that time’s simple tools, a pencil and pieces of paper:
Then, my father seeing that I really loved it, decided to buy me a typewriter (I unfortunately don’t have it anymore, but it was this model):
Besides the fact that it was difficult at first and hurt my fingers since the keys were so hard, it did improve the presentation of my writings by quite a bit, I even allowed myself to make ASCII art even though I didn’t know it would be called that way a decade later:
And when the occasion arose, I had to draw things myself on the paper:
I even went as far as making fake old maps to add to the mystery of the fiction I was writing:
At the time, if you wanted to know about one place where your story was taking place, you basically had to go there and get some documentation:
You could also read lots of books to get a grasp of the place, its atmosphere, its inhabitants and culture, etc. You had to be a real detective.
Then my parents decided that it was time for me to have a computer,
This thing was top notch at the time, it had no hard disk and everything had to be on floppy disks which weren’t so reliable. It was a great improvement on the typewriter, though, and soon MSDOS had no secrets for me. I added a 20 Mb (yes, megabytes) hard disk later which cost me an arm and a leg at the time… I could use Word 2.0 to write, it was great. You could FIX things without typing back a full page! And then, PRINT it and write gibberish on it as much as you wanted to!
Great times. Believe it or not, I still have the files for these books.
Since then, and that’s like 30 years now, nothing much has changed when it comes to the comfort of writing. Of course, you can now travel the world from your desk by watching videos and reading traveler blogs, there is more material around than you can handle anyway.
But the writing, technically? Good ol’ Word. Ah, Libre Office has come around so that you don’t depend on a private company anymore, but that’s pretty much all there is to it.
Of course, in the more recent years, self-publishing has enabled anyone to publish books, while publishing anything was practically impossible before unless an editor accepted to support you.
Tools and Constraints
There are some tools for professional writers. I won’t quote them here because I don’t want to rant, but the added value doesn’t compensate for their price, at least that’s my own opinion.
As a writer, I have quite a number of needs in order to write efficiently:
describe the characters in my story, have their personality and picture at hand whenever I need it,
describe the places where my story happens, possibly along with pictures, maps or drawings,
dynamically design the plot in the most flexible way possible, by quickly arranging events and/or themes seamlessly,
have an overview of the entire book the whole time to see where I stand,
count words inside chapters to make sure they are roughly balanced (Word documents count the total words of the document, they don’t break the counts into chapters),
handling of Table of Contents, presentation of the book, references, footnotes, etc., should be easy and not troublesome, in fact you should never even think about those as it would distract you from writing,
navigate efficiently through the book with shortcuts rather than having to scroll pages and pages to reach one chapter,
have the finished product in the form of an epub and various pdf formats (one for reading on a screen, one for a small paperback edition with small characters and at least one for a big paperback edition for people with poor vision),
manage to have a history of changes.
Frankly, none of the current software can deal with all these constraints easily. Word/LibreOffice documents are a nightmare. LaTeX constantly distracts you from the contents and doesn’t provide an easy way to navigate through the whole document (I wrote my PhD using LaTeX).
Mind Maps are the Perfect Tool
In the meantime, as a computer engineer, I started using Mind Maps at work to organize ideas. Scientific, computer-related ideas.
If you don’t know what a Mind Map is, it’s just a simple tree of ideas such as this:
You organize your ideas in nodes which are broken into smaller nodes as you refine your ideas. These are great for technical planning and thinking.
Some day, I started planning a new book inside a mind map. Just to draw the basic canvas of the story. Then I added my characters into it.
The main plot was in front of me, the characters next to it. Why not write the book inside the mind map? I know that, as soon as you start breaking your ideas into different documents, some of these documents will become out of date very quickly. By writing directly inside the mind map, I had only one document to maintain.
Most Mind Mapping software allows to type some HTML notes inside every node, that’s where I typed the main text of the book. And because it’s HTML, I can add images, put some formatting, bold, etc.
Converting a Mind Map to PDF and EPUB
To my knowledge, there is no converter to create a PDF or an EPUB from a Mind Map. If you think about it, a Mind Map is a simple text document that can be easily parsed, in the meantime libraries to generate PDFs exist, while an EPUB is a simple Zip file with some HTML files inside.
So I wrote a converter in Java, which also counts the number of words in every chapter and sub-chapter.
Thanks to this, I can easily:
have everything in one place with all I need visible in one document: the characters and locations along with the basic ideas, the whole book where chapters are nodes and sub-chapters are sub-nodes, and the nodes’ contents is the text of the book itself, so it’s extremely fast and easy to navigate from one part of the book to another,
navigate from a character to a given chapter with a simple mouse click,
move ideas, events, plots around during the planning phase, while developing characters and locations in the same document,
count words in every chapter and sub-chapter with my converter to make sure that things are not totally out of balance,
have one single source file for many output formats for the readers, which are even described in the Mind Map,
Mind Maps are text files, it is easy to compare a file with a previous backup to see what has changed.
Here is an example of a test mind map that is later transformed into a book (nodes with a yellow icon have notes typed into them):
The generated PDF looks like this:
And the generated Epub is readable on any reader, uploadable to any self-publishing platform.
I hope this converter can help other people as well. Note that its current version as I write this article is rather limited but is perfectly suitable for a simple novel. Its limitations are listed in the description of the tool itself on gitlab.
Did you like this? Let me know in the comments below!
In this digital era, we all have data that we care about. You certainly wouldn’t want to lose most of your earliest baby pictures. 😀
That data is very diverse, both in its nature and in its dynamism. You have static backups such as your baby pictures, but also very dynamic data such as your latest novel. You also have a lot of data that you probably don’t want to back up at all, such as downloaded files and programs. Well, if those files are actually your bank statements, you may want to have a backup in case something goes awfully wrong.
Things go wrong sometimes
Many people store their “stuff” on their computer, and that’s about it. Then one day, the computer crashes. Bad news, the hard disk is dead. Woops.
The thing is, hard disks fail. In 30 years of dealing with computers on a daily basis, I’ve experienced on average one hard disk failure every 2 years, and I don’t even mention the countless floppy disks that died in my hands. 😀 Maybe I’m unlucky. Maybe I use computers too much.
Regardless, I know people around me who also experienced hard disk failures and were not prepared for them. Some of them took it well, invoking destiny, others didn’t take it so well. But in any case, when it comes to data loss, destiny can be bent. And although I’ve had mostly hard drive failures, SSDs fail too, and in an even worse way since they generally give very little warning signs (if any) and the whole disk is gone at once, whereas on traditional hard drives it may still be possible to retrieve some of the data. USB keys and SD cards are no exceptions, I’ve found they fail quite often, even the ones from established brands.
Most of the time, trained and highly skilled professionals can recover most of the data using specialized equipment. For some examples of what is possible, you can check out this video channel of a very talented data recovery expert for amazing videos. But that comes at a cost. And recovering everything is not always possible.
You can cheat destiny with redundancy!
The good thing about computers is that, unlike paper data, digital stuff can be copied over and over, and that process is very easy and lossless. You just need to use this capability!
The first step towards minimizing the risk of losing data because of a hard disk failure is to set up a RAID (Redundant Array of Independent Disks). The basic idea is to spread your data and duplicate it on several disks, so that if one fails, your data is still on the other disks and you have cheated destiny. We will cover that in the second part of this series.
Redundancy Is Not A Backup
But keep this motto in mind: “Redundancy Is Not A Backup”. You have your array of disks and you can be sure now that even if one hard disk fails, you are still safe. Now, what if a second hard disk fails just after that? What if a power surge fries all your disks? Hardware failures happen, sometimes of something else (motherboard, SATA controller, etc) that even corrupts your data like it happened to this guy. Viruses encrypt all your data and ask for a 1 million $ ransom to get it back. Human error is always possible and you may mistakenly delete some important files. What if your apartment gets robbed? What if it burns or gets flooded? And yes, it even happens to the best!
This is why, along with redundancy, you always NEED backups. You should obviously not store them anywhere near your computer, ideally not even in your home in case something bad happens there. We’ll get into more detail about this in the third part of this series.
Encrypt your backups
Last but not least, as soon as you store your backups outside of your home, then comes the problem of privacy: what if someone comes across your backup and gets access to your data? You may not care about some of it being accessed by strangers, but you will probably want to shield some of your precious files from prying eyes. That will be the fourth and last part of this series.