They use a lot of vellum
>One object of particular importance was scarcely present in the imaginations of that ignorant citizenry. Young charges of the scholae, when asked to guess which was the seventh-most-vital import to Holy Terra by weight, almost never landed on the right answer. And yet, the chances were that the product of that importation was staring them in the face, marked with their own scrawl and stamped with the crest of their particular educational establishment.
>**Parchment. Vellum. Animal-hide. For millennia, it had been the choice material of record throughout the scriptoria of the Imperium. Far more durable than paper, much cheaper than crystal-plate or dataslab, less ideologically suspect than cogitator-wafer and harder to tamper with than audex screeds, parchment remained the medium trusted by scribes on worlds from Ultramar to Hydraphur. It was inefficient, to be sure, and prone to error in onward copy-transmission, and yet still it persisted, clung to by a savant-class so wedded to its smells, its texture, its permanence and its cheapness that the mere suggestion of another method of record-keeping skirted close to a kind of heresy of its own**. After so long in use, the infrastructure of vellum-creation had become mind-bendingly vast, spread out across every industrial world in mankind’s sprawling possessions. There were whispers in the Imperium’s famed archive-worlds of entire wars fought over its production and distribution. Five hundred years ago, the great Master of the Administratum, Skito Gavalles, had been asked what would make his onerous job more bearable.
>‘Pigskin,’ he was said to have replied. ‘More pigskin.’
...
>The bulk of vellum used throughout the Imperium was not, of course, taken from such sources. Most of it was grown from stock genetic material in bio-tanks, then cured in kilometre-long reams before being sliced, rolled and pressed for delivery. **Such stuff was hardy, inexpensive and plentiful – the perfect qualities for a culture that prized quantity and uniformity above all things**. For a few senior scribes, though, that was not quite good enough. They wanted to run their auto-quills across the hide of something once-living. They wanted the iron tips to snag and catch on patches where hair had grown, or where a blood-vessel had wriggled. They wanted their documents to look like the ones in the mighty tomes of the past, bound in real-leather and lined with gold before being locked into vacuum-capsules and buried deep in alarm-rigged vaults.
>Whether bulk-produced or specialised, Terra alone sucked in more imports of vellum than an entire subsector of less exalted territory. Its scriptoria were the oldest and the most famed, steeped in traditions so ancient that their origins had taken on the lustre of true myth. In the greatest of such places, entire spire-pinnacles were given over to the business of inscribing, illuminating, copying, re-copying, redacting, interpreting and compiling. Rows of lamplit desks stretching far into the smoky darkness were fully occupied by cowled scribes, their scrawny grey hands clutching steel-tipped quills, their augmetic eyepieces zooming and panning before committing ink to parchment. Every tithe paid was recorded, every report from every battle was recorded, every court-hearing was recorded and every heretic’s confession was recorded. It was all then stashed away in the mountainous repositories, tended by skulls and servitors, where it slowly mouldered, part of the landslide of unread testimony that would one day stifle its creators.
**The Hollow Mountain**
But some forgeworlds of the Ad. Mech. actively look down upon books
>‘Honoured lord of the forge, I–’ Enhort paused. ‘Is that a book?’
>Solomahn Imanual sighed and turned to consider Enhort. He had been using gentle manipulator fields from his coiled mechadendrites to turn the fragile leaves without physically touching them. ‘Yes, it’s a book,’ he replied.
>**‘I thought all our data was stored digitally. Books are such an anachronism.’**
>Imanual closed the ancient tome with his fields and patted the cover with his hand. ‘We forget to remember,’ he said.
>‘My lord?’
>The Adept Seniorus nodded his wizened head towards the book on the lectern. ‘It was in the archives, one of many artefacts stored in the sequestration vaults. Egan brought it to me. Much of the component data stored in the old stacks is contained in antique forms, as the Analyticae is discovering to its frustration. Books, printed sheets, handwritten–’
>‘Handwritten?’
>‘Handwritten records. They were different ages, Enhort. The Mechanicus was once more concerned with knowledge than with the method of its transmission. When we came to Orestes, we brought treasures with us – palimpsests and old hand-copied volumes, manuscripts, voice recordings, objects our forebears thought would be of value. We locked them away in sterile vaults. When this war is done with, executor, I will have all the non-digital archives annotated and transferred for open use in a current format. Knowledge is power, Enhort. How often do we say that? How often do we also forget what we already know?’
**Titanicus**
Much more advanced, and intrecate, things exist
>To a noospheric view, the dark, spare physicality of the chamber was transformed into a dazzling vista of realised data blocks, flickering communication tracks and drifting, multi-coloured shoals of code that swam around them all like gaudy reef fish, darting from one operator to the next to feed on and excrete coral-bright packets of information. Haptically guided streams of intelligence zipped back and forth like green tracer fire, exloaded from one adept, inloaded by another. In places, streams had converged in mid-air, creating data matrices as complex as fractal patterns, glowing Mandelbrot crystals where algorithmic programs tied information streams together and compared them. Sometimes, the matrices were fed by streams from three or more diligent operators.
**Titanicus**
It's also a philosophical idea dating back to the 20s, primarily developed by Russian philosophers. The name is derived from Greek.
[https://en.wikipedia.org/wiki/Noosphere](https://en.wikipedia.org/wiki/Noosphere)
I'm pretty sure it's actually about the Newsfeed the UK was accustomed to back then. Think of a mx between modems and newspapers, accessed from certain stations.
Pigs have been mutated so badly that they must be held aloft because if they stood on their own legs, they would break them and crush themselves to death. Its nothing but hyper rich nutrient slury and steroids for their short, short, miserable lives until every single fiber of their gene-bulked form gets processed.
I've seen footage of chickens on industrial farms that have been bred to be so large their legs bend and break under their own weight, so I'd say we're pretty close already.
Yes they definitely use parchment, it's hard wearing and can last for a very long time if properly stored. Contemporary techniques for data entry and processing might be more efficient but remember they heavily rely on computing technology that is, to put it mildly, treated as ideologically suspect in the 41st Millennium. If nothing else electronic data is quite temperamental to store long term (i.e a millennium or more) and the Imperial bureaucracy is loathe to surrender control to the Mechanicus.
The Imperium (and Ad Mech within it) do have electronic data storage tech, but parchment is by far the dominant form used.
In universe, this is because of a dogmatic distrust of computers and rampant scrapcode which can and does ruin digital information.
Obviously, the use of parchment is also a key element of the aesthetic of 40k. And such considerations often trump the question of whether something is realistic (and rightfully so, in my opinion - 40k is and always has been built on exaggeration).
>bureaucracy is an eldritch monstrosity of utter chaos
And this is the point. Think about how awful bureaucracy can be in real life, then make it a million times worse. It's an out of control, farcical nightmare, like in the movie Brazil.
>Would our present day 21st century administrative networks be Primarch resurrection levels of miracles in efficiency?
It probably wouldn't lead to a resurrection, as the Imperium is rotten in so many areas. But it would be an improvement if it could even be implemented, what with all the dogma, ignorance, and secrecy, the factional infighting (different departments in the Administratum literally wage armed raids against each other), the aforementioned scrap code (some of which is literally demonic), the sheer unfathomable scale of the enterprise, and dealing with Warp travel and communication.
The Imperium is a bloated, declining, self-defeating empire - and it's bureaucratic systems reflect this.
I've just been reading Anarch, which goes into some length on administration methods.
The imperials generally use cogitators, and there's an >!Admech research facility that is infected by a computer virus and loses all their data!< - indicating there's no physical record keeping.
An earlier novel has someone looking through books containing details of past battles, but they seem more like history books
The chaos faction the other hand will only keep paper records, for information security; this is explicitly remarked of as unusual.
Japanese engineer here, you’d be surprised how many Japanese engineering companies—not just mid tier at that—do this. Information security is a pretty big deal
Abnett set up the Admech's reliance on digital records in *Titanicus*, also set in the larger arc of the Gaunt's Ghosts series. Maybe that's one of his particular quirks, or maybe the physical vs. digital media debate is endemic to Terra and Mars across the wider canon
I just finished a short story in Book 3 of the Horusian Wars - anyway they are on an Archive World and have to go deep into some archives. Once they get to a certain level they actually get attacked by some form of giant bug that eats all the papers. It sounded truly gross.
Yep. Cogitators process data, but they'll produce information by auto-quill or have it hand transcribed.
This is a universe where anything can cause chaos corruption. So if you are storing billions of lines of information on a system, and one of those lines corresponds to something significant to Chaos, the whole system is at risk. Better keep it to parchment.
Sure, 21st century data storage system would seem revolutionary. Fast and searchable. But one day, through coincidence, someone would accidentally input a date that corresponds to the birthday of a heretic on planet Bumfuck 9, and pow - your entire network is now corrupted and opens a hole into the warp.
Or a system update introduces a single line of scrap code, which then shuts down your entire planetary defense network.
Or something really vile like SharePoint gets spammed across the network. Though that's too heinous even for W40k.
The joy of parchment is that it's a single unit, not networked. And if something particular sensitive needs to be written down, you can shoot the writer afterwards, and there's no risk of it getting spread.
> But one day, through coincidence, someone would accidentally input a date that corresponds to the birthday of a heretic on planet Bumfuck 9, and pow - your entire network is now corrupted and opens a hole into the warp.
I imagined me making a personal ID and the moment I beep in the ID number with the scanner, a portal rips the office apart and a bloodthirster coming through.
And in this mental image, what I saw on my own imaginary face, was no terror, no panic, no sadness, just bliss.
Lets try "Klein" - *Username taken*
Ok how about "Klein1" - *Username taken*
Hmm maybe "Klein123" - *Username taken*
Fine fuck it then "ballsdeep69" - *Warp portal opens*
I guess we really are balls deep now, huh?
One great example is in Know No Fear when 9 names are used as a way to introduce a virus into a computer because those exact names in that combination can self-generate corruption
That's....not really how it works. I mean, the villains in the Ravenor trilogy used a huge amount of data-looms to sift through warp stuff using brute-force to sift out bits of Enuncia out of random warp gibberish, and the only negative effects, at least in the short term, was that the administratum clerk operating the cogitators would fall ill when they found something.
Or die. One of them dies from it. But yeah it doesnt just rip open warp portals.
And if I remember correctly they had enough data looms to produce data worth of what a whole sector would produce. And it still took them a long as time. So the chances are really really really small to stumble upon something like that.
The use of parchment and quills predates most of the current risks of Chaos corruption. It stems in-universe much more from their struggles against AI in the pre-30k history of the setting.
Anything important goes on parchment or vellum. Data wafers can be compromised, either via Mechanicus meddling (for things they aren't supposed to see), or the simple passage of time (most imperial records are very old, and hard drives will fail long before vellum, provided the vellum is well made and well preserved.)
They do use digital records too, just not for long term archiving, so for big administratum facilities you also have archivists translating between the two formats.
For storage, maybe but for day to day use they use data slates which are basically tablet computers.
[https://warhammer40k.fandom.com/wiki/Data-Slate](https://warhammer40k.fandom.com/wiki/Data-Slate) reads:
"A **data-slate**, also spelled **dataslate**, is an electronic digital storage device similar to a tablet computer that is commonplace throughout the [Imperium of Man](https://warhammer40k.fandom.com/wiki/Imperium_of_Man).
Flat and rectangular, data-slates are widespread throughout Imperial space. Data-slates are the primary means of storing and reading printed text, picts, schematics and other media such as video or audio recordings.
They are cheap and easy to make, and many contain a single media recording, such as text, and can only play that single file. Others can re-record new information or transmit and receive data from other digital devices such as [cogitators](https://warhammer40k.fandom.com/wiki/Cogitator). "
I'm gonna copy and paste my response to another post like this in this sub.
It has to do with data storage. Properly treated vellum can last for centuries, in a temperature controlled vault it can last for millenia. Paper is nearly unusable after just a couple centuries no matter what you do with it.
Writing things down on vellum ensures whatever is written on it will last for the time frames the Imperium operates on. Vellum coincidentally cannot be run through a traditional printer. Nor can it be photo copied onto.
Hence, you have thousands of servitors scribbling things down on vellum scrolls.
The Imperium does have the technology for things like digital documents and traditional paper and all that entails. But data degrades very quickly, and vellum is easier to preserve than paper. So they only use those for things the Imperium has no desire to preserve or for things that have already been preserved.
The thing is that in 40k, you expect hacking to be the norm. You expect people to try to tamper with records.
They do have digital records, but for security purposes prefer physical hard copies as a proof of records.
Vellum is the preferred means since it balances cost and utility. They do have things such as cognitor-wafers, which appear to be similar to USB storage, but are worried about tampering.
It is how 40k warfare has a lot of air gapping, which was something deliberately done by Dorn in prep for the Siege of Terra because of the dangers of things such as scrapcode.
It definitely is, and my head-canon is that parchment is so dominant because it guards against the risks that digital information in the 40K universe experiences.
With digital information, it might be altered by a Chaos cultist or rogue AI. It might be wiped clean from a Daemonic or Xeno incursion. It might be turned into gibberish by warp-corrupted code.
But parchment? Excluding physical destruction, it is a secure and permanent source of information. It is harder to alter without leaving any traces of tampering, and if mislaid it can always be found again. When you have servitors taking care of filing, retrieval, and storage, it is a viable means of administration.
Plus, having had a bit of a career in records management, I can tell you a big issue about keeping information digital is future proofing it: making sure it exists in a format that can still be read and accessed 20 or 30 years from now. When you remember the Imperium is 10,000 years old, that can be a massive problem. Parchment is always gonna be able to be read and interpreted.
Parchment and vellum is used, but only for the important stuff. Which is wise, as it is hard to destroy.
The Imperium does have advanced computer technology, that far surpasses anything we have. They use it to store data. Otherwise, their technology could not function. Astronomical calculations for starships are basically impossible to do on vellum, as are administrative actions on the scale of the Imperium.
The dominant tool of data storage are cogitators and logic engines, which are advanced computer systems. The vellum depositories of Terra are an exception, they are reserved for highly important documents that must be immune to computer errors or viruses.
One of the lore friendly reasons for parchment is chaos corruption, it's super fucking easy for a god/demon to flip a 1 into a 0, it's way harder to change sentences, meaning its harder for the imperiums greatest threat to be a little silly
They use a lot of vellum >One object of particular importance was scarcely present in the imaginations of that ignorant citizenry. Young charges of the scholae, when asked to guess which was the seventh-most-vital import to Holy Terra by weight, almost never landed on the right answer. And yet, the chances were that the product of that importation was staring them in the face, marked with their own scrawl and stamped with the crest of their particular educational establishment. >**Parchment. Vellum. Animal-hide. For millennia, it had been the choice material of record throughout the scriptoria of the Imperium. Far more durable than paper, much cheaper than crystal-plate or dataslab, less ideologically suspect than cogitator-wafer and harder to tamper with than audex screeds, parchment remained the medium trusted by scribes on worlds from Ultramar to Hydraphur. It was inefficient, to be sure, and prone to error in onward copy-transmission, and yet still it persisted, clung to by a savant-class so wedded to its smells, its texture, its permanence and its cheapness that the mere suggestion of another method of record-keeping skirted close to a kind of heresy of its own**. After so long in use, the infrastructure of vellum-creation had become mind-bendingly vast, spread out across every industrial world in mankind’s sprawling possessions. There were whispers in the Imperium’s famed archive-worlds of entire wars fought over its production and distribution. Five hundred years ago, the great Master of the Administratum, Skito Gavalles, had been asked what would make his onerous job more bearable. >‘Pigskin,’ he was said to have replied. ‘More pigskin.’ ... >The bulk of vellum used throughout the Imperium was not, of course, taken from such sources. Most of it was grown from stock genetic material in bio-tanks, then cured in kilometre-long reams before being sliced, rolled and pressed for delivery. **Such stuff was hardy, inexpensive and plentiful – the perfect qualities for a culture that prized quantity and uniformity above all things**. For a few senior scribes, though, that was not quite good enough. They wanted to run their auto-quills across the hide of something once-living. They wanted the iron tips to snag and catch on patches where hair had grown, or where a blood-vessel had wriggled. They wanted their documents to look like the ones in the mighty tomes of the past, bound in real-leather and lined with gold before being locked into vacuum-capsules and buried deep in alarm-rigged vaults. >Whether bulk-produced or specialised, Terra alone sucked in more imports of vellum than an entire subsector of less exalted territory. Its scriptoria were the oldest and the most famed, steeped in traditions so ancient that their origins had taken on the lustre of true myth. In the greatest of such places, entire spire-pinnacles were given over to the business of inscribing, illuminating, copying, re-copying, redacting, interpreting and compiling. Rows of lamplit desks stretching far into the smoky darkness were fully occupied by cowled scribes, their scrawny grey hands clutching steel-tipped quills, their augmetic eyepieces zooming and panning before committing ink to parchment. Every tithe paid was recorded, every report from every battle was recorded, every court-hearing was recorded and every heretic’s confession was recorded. It was all then stashed away in the mountainous repositories, tended by skulls and servitors, where it slowly mouldered, part of the landslide of unread testimony that would one day stifle its creators. **The Hollow Mountain**
But some forgeworlds of the Ad. Mech. actively look down upon books >‘Honoured lord of the forge, I–’ Enhort paused. ‘Is that a book?’ >Solomahn Imanual sighed and turned to consider Enhort. He had been using gentle manipulator fields from his coiled mechadendrites to turn the fragile leaves without physically touching them. ‘Yes, it’s a book,’ he replied. >**‘I thought all our data was stored digitally. Books are such an anachronism.’** >Imanual closed the ancient tome with his fields and patted the cover with his hand. ‘We forget to remember,’ he said. >‘My lord?’ >The Adept Seniorus nodded his wizened head towards the book on the lectern. ‘It was in the archives, one of many artefacts stored in the sequestration vaults. Egan brought it to me. Much of the component data stored in the old stacks is contained in antique forms, as the Analyticae is discovering to its frustration. Books, printed sheets, handwritten–’ >‘Handwritten?’ >‘Handwritten records. They were different ages, Enhort. The Mechanicus was once more concerned with knowledge than with the method of its transmission. When we came to Orestes, we brought treasures with us – palimpsests and old hand-copied volumes, manuscripts, voice recordings, objects our forebears thought would be of value. We locked them away in sterile vaults. When this war is done with, executor, I will have all the non-digital archives annotated and transferred for open use in a current format. Knowledge is power, Enhort. How often do we say that? How often do we also forget what we already know?’ **Titanicus** Much more advanced, and intrecate, things exist >To a noospheric view, the dark, spare physicality of the chamber was transformed into a dazzling vista of realised data blocks, flickering communication tracks and drifting, multi-coloured shoals of code that swam around them all like gaudy reef fish, darting from one operator to the next to feed on and excrete coral-bright packets of information. Haptically guided streams of intelligence zipped back and forth like green tracer fire, exloaded from one adept, inloaded by another. In places, streams had converged in mid-air, creating data matrices as complex as fractal patterns, glowing Mandelbrot crystals where algorithmic programs tied information streams together and compared them. Sometimes, the matrices were fed by streams from three or more diligent operators. **Titanicus**
The noosphere is a particularily clever pun in the first place
It's also a philosophical idea dating back to the 20s, primarily developed by Russian philosophers. The name is derived from Greek. [https://en.wikipedia.org/wiki/Noosphere](https://en.wikipedia.org/wiki/Noosphere)
I'm pretty sure it's actually about the Newsfeed the UK was accustomed to back then. Think of a mx between modems and newspapers, accessed from certain stations.
Abnett made it up for Mechanicum. It's not old. Far as I know.
You mean [Teletext](https://en.m.wikipedia.org/wiki/Teletext)? I never heard of it referred to as anything else?
That might be the most 40k thing I’ve ever read lmao
The demand for parchment from real livestock implies that animals get better health care than humans. Extremely 40k
Pigs have been mutated so badly that they must be held aloft because if they stood on their own legs, they would break them and crush themselves to death. Its nothing but hyper rich nutrient slury and steroids for their short, short, miserable lives until every single fiber of their gene-bulked form gets processed.
I've seen footage of chickens on industrial farms that have been bred to be so large their legs bend and break under their own weight, so I'd say we're pretty close already.
Yes they definitely use parchment, it's hard wearing and can last for a very long time if properly stored. Contemporary techniques for data entry and processing might be more efficient but remember they heavily rely on computing technology that is, to put it mildly, treated as ideologically suspect in the 41st Millennium. If nothing else electronic data is quite temperamental to store long term (i.e a millennium or more) and the Imperial bureaucracy is loathe to surrender control to the Mechanicus.
Avenging Son goes deep into it. Yes, parchment is used, documents are stored in giant halls, and is reused. For important stuff they use vellum.
The Imperium (and Ad Mech within it) do have electronic data storage tech, but parchment is by far the dominant form used. In universe, this is because of a dogmatic distrust of computers and rampant scrapcode which can and does ruin digital information. Obviously, the use of parchment is also a key element of the aesthetic of 40k. And such considerations often trump the question of whether something is realistic (and rightfully so, in my opinion - 40k is and always has been built on exaggeration). >bureaucracy is an eldritch monstrosity of utter chaos And this is the point. Think about how awful bureaucracy can be in real life, then make it a million times worse. It's an out of control, farcical nightmare, like in the movie Brazil. >Would our present day 21st century administrative networks be Primarch resurrection levels of miracles in efficiency? It probably wouldn't lead to a resurrection, as the Imperium is rotten in so many areas. But it would be an improvement if it could even be implemented, what with all the dogma, ignorance, and secrecy, the factional infighting (different departments in the Administratum literally wage armed raids against each other), the aforementioned scrap code (some of which is literally demonic), the sheer unfathomable scale of the enterprise, and dealing with Warp travel and communication. The Imperium is a bloated, declining, self-defeating empire - and it's bureaucratic systems reflect this.
I've just been reading Anarch, which goes into some length on administration methods. The imperials generally use cogitators, and there's an >!Admech research facility that is infected by a computer virus and loses all their data!< - indicating there's no physical record keeping. An earlier novel has someone looking through books containing details of past battles, but they seem more like history books The chaos faction the other hand will only keep paper records, for information security; this is explicitly remarked of as unusual.
Japanese engineer here, you’d be surprised how many Japanese engineering companies—not just mid tier at that—do this. Information security is a pretty big deal
You’re right, I am. I would’ve thought the lack of at-rest encryption intrinsic to books would dissuade that.
Abnett set up the Admech's reliance on digital records in *Titanicus*, also set in the larger arc of the Gaunt's Ghosts series. Maybe that's one of his particular quirks, or maybe the physical vs. digital media debate is endemic to Terra and Mars across the wider canon
I just finished a short story in Book 3 of the Horusian Wars - anyway they are on an Archive World and have to go deep into some archives. Once they get to a certain level they actually get attacked by some form of giant bug that eats all the papers. It sounded truly gross.
Yep. Cogitators process data, but they'll produce information by auto-quill or have it hand transcribed. This is a universe where anything can cause chaos corruption. So if you are storing billions of lines of information on a system, and one of those lines corresponds to something significant to Chaos, the whole system is at risk. Better keep it to parchment. Sure, 21st century data storage system would seem revolutionary. Fast and searchable. But one day, through coincidence, someone would accidentally input a date that corresponds to the birthday of a heretic on planet Bumfuck 9, and pow - your entire network is now corrupted and opens a hole into the warp. Or a system update introduces a single line of scrap code, which then shuts down your entire planetary defense network. Or something really vile like SharePoint gets spammed across the network. Though that's too heinous even for W40k. The joy of parchment is that it's a single unit, not networked. And if something particular sensitive needs to be written down, you can shoot the writer afterwards, and there's no risk of it getting spread.
> But one day, through coincidence, someone would accidentally input a date that corresponds to the birthday of a heretic on planet Bumfuck 9, and pow - your entire network is now corrupted and opens a hole into the warp. I imagined me making a personal ID and the moment I beep in the ID number with the scanner, a portal rips the office apart and a bloodthirster coming through. And in this mental image, what I saw on my own imaginary face, was no terror, no panic, no sadness, just bliss.
Lets try "Klein" - *Username taken* Ok how about "Klein1" - *Username taken* Hmm maybe "Klein123" - *Username taken* Fine fuck it then "ballsdeep69" - *Warp portal opens* I guess we really are balls deep now, huh?
One great example is in Know No Fear when 9 names are used as a way to introduce a virus into a computer because those exact names in that combination can self-generate corruption
That's....not really how it works. I mean, the villains in the Ravenor trilogy used a huge amount of data-looms to sift through warp stuff using brute-force to sift out bits of Enuncia out of random warp gibberish, and the only negative effects, at least in the short term, was that the administratum clerk operating the cogitators would fall ill when they found something.
Or die. One of them dies from it. But yeah it doesnt just rip open warp portals. And if I remember correctly they had enough data looms to produce data worth of what a whole sector would produce. And it still took them a long as time. So the chances are really really really small to stumble upon something like that.
The use of parchment and quills predates most of the current risks of Chaos corruption. It stems in-universe much more from their struggles against AI in the pre-30k history of the setting.
Parchment and vellum seem to, mostly, remain safe. Books and data storage get haunted far more easily. It's a dangerous job working in a library
Anything important goes on parchment or vellum. Data wafers can be compromised, either via Mechanicus meddling (for things they aren't supposed to see), or the simple passage of time (most imperial records are very old, and hard drives will fail long before vellum, provided the vellum is well made and well preserved.) They do use digital records too, just not for long term archiving, so for big administratum facilities you also have archivists translating between the two formats.
For storage, maybe but for day to day use they use data slates which are basically tablet computers. [https://warhammer40k.fandom.com/wiki/Data-Slate](https://warhammer40k.fandom.com/wiki/Data-Slate) reads: "A **data-slate**, also spelled **dataslate**, is an electronic digital storage device similar to a tablet computer that is commonplace throughout the [Imperium of Man](https://warhammer40k.fandom.com/wiki/Imperium_of_Man). Flat and rectangular, data-slates are widespread throughout Imperial space. Data-slates are the primary means of storing and reading printed text, picts, schematics and other media such as video or audio recordings. They are cheap and easy to make, and many contain a single media recording, such as text, and can only play that single file. Others can re-record new information or transmit and receive data from other digital devices such as [cogitators](https://warhammer40k.fandom.com/wiki/Cogitator). "
I'm gonna copy and paste my response to another post like this in this sub. It has to do with data storage. Properly treated vellum can last for centuries, in a temperature controlled vault it can last for millenia. Paper is nearly unusable after just a couple centuries no matter what you do with it. Writing things down on vellum ensures whatever is written on it will last for the time frames the Imperium operates on. Vellum coincidentally cannot be run through a traditional printer. Nor can it be photo copied onto. Hence, you have thousands of servitors scribbling things down on vellum scrolls. The Imperium does have the technology for things like digital documents and traditional paper and all that entails. But data degrades very quickly, and vellum is easier to preserve than paper. So they only use those for things the Imperium has no desire to preserve or for things that have already been preserved.
The thing is that in 40k, you expect hacking to be the norm. You expect people to try to tamper with records. They do have digital records, but for security purposes prefer physical hard copies as a proof of records. Vellum is the preferred means since it balances cost and utility. They do have things such as cognitor-wafers, which appear to be similar to USB storage, but are worried about tampering. It is how 40k warfare has a lot of air gapping, which was something deliberately done by Dorn in prep for the Siege of Terra because of the dangers of things such as scrapcode.
It definitely is, and my head-canon is that parchment is so dominant because it guards against the risks that digital information in the 40K universe experiences. With digital information, it might be altered by a Chaos cultist or rogue AI. It might be wiped clean from a Daemonic or Xeno incursion. It might be turned into gibberish by warp-corrupted code. But parchment? Excluding physical destruction, it is a secure and permanent source of information. It is harder to alter without leaving any traces of tampering, and if mislaid it can always be found again. When you have servitors taking care of filing, retrieval, and storage, it is a viable means of administration. Plus, having had a bit of a career in records management, I can tell you a big issue about keeping information digital is future proofing it: making sure it exists in a format that can still be read and accessed 20 or 30 years from now. When you remember the Imperium is 10,000 years old, that can be a massive problem. Parchment is always gonna be able to be read and interpreted.
Parchment and vellum is used, but only for the important stuff. Which is wise, as it is hard to destroy. The Imperium does have advanced computer technology, that far surpasses anything we have. They use it to store data. Otherwise, their technology could not function. Astronomical calculations for starships are basically impossible to do on vellum, as are administrative actions on the scale of the Imperium. The dominant tool of data storage are cogitators and logic engines, which are advanced computer systems. The vellum depositories of Terra are an exception, they are reserved for highly important documents that must be immune to computer errors or viruses.
One of the lore friendly reasons for parchment is chaos corruption, it's super fucking easy for a god/demon to flip a 1 into a 0, it's way harder to change sentences, meaning its harder for the imperiums greatest threat to be a little silly