8
votes
Accepted
Why splitted text files is bigger than a large one with the same content?
Filesystem overhead.
Every time you create a file, the filesystem reserves space on disk to store the file name, and other metadata like its permissions, creation date, etc. It also has to maintain a ...
- 14.4k
7
votes
Typical file structure
First, let me state that you may have things to unlearn. Files that are a stream of bytes are very much the rule, and have been for a long time. Almost all filesystems store a sequence of bytes, and ...
6
votes
Accepted
Is it possible to wear-level a FAT32 file system?
The OS references blocks using a "logical block address". The SD card then maps this to a physical page of flash memory. With wear leveling, each time data in that block is changed, it ...
D.W.♦
- 156k
6
votes
What is a file?
According to Wikipedia, a computer file is simply a resource for storing information. The term appears to have originated in the punch card era, where a computer program was literally stored in a file ...
- 171
5
votes
Accepted
What type of an algorithm is being used for directory structure scanning?
For most file systems, a directory lists its entries in a certain order, so reading ("scanning") an individual directory will return its entries in that order.
But when it comes to scanning whole ...
- 5,359
3
votes
Accepted
Linked allocation in operating systems: why not use a doubly linked list?
Singly and doubly linked lists have the identical (terrible) linear access time. Using doubly linked lists would not help performance. The only benefit you'd get is that reading file backwards is more ...
- 232
3
votes
Why can't un-journaled filesystems be resized?
The "file allocation table" (which gives the FAT filesystem its name) is a fixed-size array "statically allocated at the time of formatting." Its size is determined by the size of the partition, ...
- 11.9k
3
votes
What is the term for two file formats that describe the same amount of information?
I think that many programmers would look at it in terms of the conversions between the two formats, and say that each format can be converted to the other losslessly, and that it's possible to make a ...
- 319
3
votes
Accepted
What is the file system of ram?
Think of the file system and its files as a big cabinet with lots of physical folders in an office of bureaucrats. The sheets in the folders are arranged in fixed ways such that every bureaucrat knows ...
- 2,732
3
votes
Accepted
What's the directory structure on disk that keeps the information of all files?
Your intuition is mostly correct. I believe the description is not really sufficient. Directory entry should at least be able to allow the OS to be able to locate some parts the file on disk for I/O ...
- 421
3
votes
SSD vs HDD Retrieval Time
TL;DR: You don't have to worry about seek times with SSDs like you do with hard disks. As a first-order approximation, you can think of them as random-access devices.
SSDs let you read and write ...
D.W.♦
- 156k
3
votes
Is it possible to wear-level a FAT32 file system?
When flash storage is exposed directly to the operating system, it's used with a file system specifically designed for flash, like JFFS2.
USB and SATA flash drives emulate Winchester hard drives, and ...
- 2,092
3
votes
How can I prove the file on DVD is the original?
There's no value in just owning the file of an NFT, that's why there are so many memes about right clicking JPEGs and saving them. Owning the smart contract is what really matters in the NFT world, so ...
- 352
3
votes
Why can't we mount multiple filesystem in same mountpoint?
SunOS 4.1 supported something like what I think you're getting at, called the Translucent File System. The idea is you could stack multiple filesystems in the same location.
When searching for a file, ...
- 21.6k
2
votes
Accepted
Deleted data remains on a disk until?
It depends on the file system used and preferences provided, but in the most common case - deleted data is marked as deleted (dirty) and is used when some new data is to be written. Priority of usage ...
- 9,425
2
votes
Accepted
Typical file structure
I've never heard of sequential files, but apparently the term can mean two things:
Data which can only be accessed sequentially, for example the contents of a backup tape.
Record-based files (what ...
- 275k
2
votes
What is a file?
I think of a file as a sequence of bytes. Even after it loses its name (usually caused by a call to rm, which unlinks it), it still exists on the disk until its chunks get overwritten by other stuff. ...
- 209
2
votes
File systems and writing one
OEM Parameter block
The OEM block not only stores data about the filesystem, it also contains information about the physical hard drive geometry, or about how files are laid out on your hard drive or ...
- 121
2
votes
File systems and writing one
The MBR refers to the format used by (many but not all, and slowly being replaced by GPT) disk to identity partitions. A partition is simply a contiguous range of blocks on the disk. A partition is ...
- 1,181
2
votes
Accepted
Why can't un-journaled filesystems be resized?
It’s just historical.
Old file systems are not journaled, and they cannot be resized. At some point in time journaling was added, and at some point in two resizing was added. So new file systems ...
- 28.4k
2
votes
Accepted
No. of disk blocks writes required for writing the file
The correct answer is: greater or equal to K/D, depending on the fact that K can be a multiple of D or not. So, the answer is actually c), which differs from the other three answers.
Note that if ...
- 809
2
votes
Accepted
How pictures and videos are usually loaded in Memory?
Just having malicious instructions loaded into memory is not a problem in itself. Instructions (code) is just binary, so it might be stored in the data segment.
Where it becomes a problem is if ...
D.W.♦
- 156k
2
votes
Accepted
Would this be the correct time complexity?
Since you have $n$ word, the put(k,v) operation needs to be done at least $n$ times. Let's say you have an algorithm that process $D$ in $o(n)$. The algorithm is ...
- 316
2
votes
How can computers tell where the beginning and end of file/packet/frame headers are?
If you click on the link you provided you'll see that the word 802.1Q is itself a link and when you read that page you'll see that the field uses a special value, a magic number if you like for the ...
- 185
2
votes
Meaning of "untyped bytes" in file systems
They mean that the data is an array of bytes, nothing more. It does not come with any type information to indicate how the data should be interpreted. It is up to applications to figure out how to ...
D.W.♦
- 156k
2
votes
Where is File Allocation Table in FAT32 file system stored?
The first five fields of the BPB (BIOS Parameter Block) in any FAT filesystem contains are following fields:
The first three bytes are the boot jump; this contains ...
- 21.6k
2
votes
Accepted
WAV file header: Why 2 bytes for channel?
The dry and somewhat unhelpful answer is: The creators of the WAV file specification deemed 65535 to be a reasonable maximum number of channels.
Any reasonable surround sound system (3.1, 5.1, 7.1) ...
- 632
1
vote
Linked allocation in operating systems: why not use a doubly linked list?
The solution that is usually used is not to use a linked list. Most common is that the OS tries to allocate as many sequential blocks as possible, and record ranges of consecutive blocks. Often only ...
- 28.4k
1
vote
Accepted
Is a file a string of zeros and ones?
Yes the File has a binary representation and it can start with a leading zero.
To verify this open any file from your computer with an hex editor and modify the leading hex to 00.
You would most ...
- 125
1
vote
How does a File System handle an internal edit to a file?
Filesystems typically don't handle internal edits to files as you describe them. When you edit a program file, a text editor will pull the whole file into memory, allow you to make modifications to a ...
- 8,051
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