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Questions tagged [filesystems]

Questions about algorithms and data structures for storing, organizing, and naming data in durable storage systems.

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12 votes
4 answers
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Why store self and parent links (. and ..) in a directory entry?

Consider an filesystem targeted at some embedded devices that does little more than store files in a hierarchical directory structure. This filesystem lacks many of the operations you may be used to ...
Gilles 'SO- stop being evil''s user avatar
9 votes
2 answers
1k views

What is a file?

I'm looking for a formal definition of file that does not only include storage but also abstractions like procfs or /dev/null (or any fuse-based file) that do not relate to storage. So far I know ...
Giacomo Tesio's user avatar
5 votes
2 answers
322 views

What if the electricity goes off while a file is being renamed?

Suppose I'm renaming a file and the electricity goes off right in the middle. Naively, it looks like the file could be in some “half-renamed” state. Maybe the name would have half the old name and ...
Anon's user avatar
  • 63
4 votes
1 answer
338 views

Is every file an integer amount of bytes?

I'm not sure whether I'm asking on the right site, since all the other questions seem to be a lot more abstract and theoretical. If I should remove the question, please tell me. Are all files on my ...
Dasherman's user avatar
  • 143
4 votes
1 answer
3k views

Why do some filesystems have fragmentation and others don't?

I try to understand why fragmentation is a problem for NTFS and FAT but not when using inodes. In all cases, files are not necessarily stored in a contiguous fashion so I don't see the problem for the ...
user2459338's user avatar
3 votes
3 answers
629 views

Typical file structure

Short version The question & answers relate to the following topics: File as a collection of records vs. file as a stream of bytes Sequential File Distinction between file data and metadata ...
bkoodaa's user avatar
  • 367
3 votes
2 answers
7k views

B-Tree and how it is used in practice

I understand what a B-Tree is (I already implemented a B-Tree in Java with insert and delete methods that preserve the invariant). However I do not understand exactly how it is used for example for ...
Nocta's user avatar
  • 121
3 votes
1 answer
85 views

Studies of file access patterns in embedded systems

I am considering what elements an operating system for Network On Chip systems might have and the issue of file systems looms large. NoCs have an embedded heritage, and their domain of use (at least ...
adrianmcmenamin's user avatar
2 votes
2 answers
88 views

Why can't un-journaled filesystems be resized?

I have yet to find an un-journaled filesystem that can be resized without data loss or intermediate conversions, and I'm wondering why that is. Filesystems like FAT, for example, leave free space at ...
ATLief's user avatar
  • 123
2 votes
1 answer
3k views

What type of an algorithm is being used for directory structure scanning?

So after learning about DFS and BFS yesterday in my class I was curious as to how is scanning on various file system being done. I spent quite a bit of time trying to look for some references on the ...
brajevicm's user avatar
2 votes
1 answer
78 views

Filing systems using index blocks

I know that a disadvantage of the index block system is that it can be wasteful of space if the files involved are mostly small in size, as index blocks are allocated from free space as required and ...
CompilerSaysNo's user avatar
2 votes
2 answers
66 views

What is the term for two file formats that describe the same amount of information?

I am working on file formats conversion. Some of them can be converted back and forth to others without losing any information (fields or precision of the numbers encoded), others file format do not ...
G M's user avatar
  • 121
2 votes
1 answer
359 views

SSD vs HDD Retrieval Time

On an HDD if data is fragmented the discs need to be spun to where the next block in the file is, so how and where data is stored can make a big difference in how long it takes to retrieve the data. ...
yitzih's user avatar
  • 121
2 votes
1 answer
3k views

How is the directory implementation done using a linear list?

I am reading Operating System Concepts by Silberchatz, Galvin, Gagne and they write that a directory can be implemented using a linear list. [pg 470, 8th ed] However, I visualize directories as a ...
user2441151's user avatar
2 votes
2 answers
135 views

How does a File System handle an internal edit to a file?

When you edit information in a file, but you add in more information than was already present, how does the file system handle it without an overflow into the next section of the file? Here's an ...
Nathaniel Benson's user avatar
2 votes
1 answer
100 views

Monitoring files in preservation archives

What are efficient and accurate techniques for monitoring the recoverability and integrity of files in very large preservation archives? In very large archives, the time taken to recompute checksums ...
Micah Beck's user avatar
2 votes
0 answers
35 views

Log-Structured Filesystem -- why do we need an explicit, scattered inode map?

From OSTEP Chp. 43: The imap is a structure that takes an inode number as input and produces the disk address of the most recent version of the inode This makes sense to me as a solution to the ...
user129393192's user avatar
2 votes
0 answers
90 views

Questions about the Dancing Tree data structure

I would be very grateful if someone can clarify a little bit about the Dancing tree data structure that the Reiser4 filesystem uses. It's a presentation topic that I picked, however, there seems to be ...
Huy Đỗ Nguyễn An's user avatar
2 votes
0 answers
39 views

Primary File Organization in DBMS - Files of ordered records (sorted files)

"Fundamental of Database Systems", 3rd ed. by Elmasri and Navathe, page 136 says: "We can physically order the records of a file on disk based on the values of one of their fields [...]&...
GuestUser's user avatar
2 votes
0 answers
107 views

Exceeding limits of virtual address space

I still am confused whether I am asking the right question but here goes Consider a X bit processor. It can address theoretically a main memory of 2^x bytes(assuming byte addressable). Now consider an ...
Rinkesh P's user avatar
  • 1,024
2 votes
1 answer
103 views

Why does CLRS refer to the disk parts as pages rather than blocks?

I recently decided to review the B-tree chapter (chapter 18, p 486 in 3ed) in Introduction Algorithms, and found that they call pages what I always referred to as blocks or clusters: In order to ...
2xMax's user avatar
  • 121
2 votes
0 answers
61 views

Importance of contiguous allocation on flash disks

All file systems I know make significant efforts to try and allocate files in contiguous blocs on a disk. But if the disk is an SSD using flash technology underneath, is there any benefit to ...
Stefan's user avatar
  • 368
2 votes
1 answer
628 views

What exactly is a "binary file"?

I suspect this may be more of a concept / theory question, but, I haven't been able to wrap my brain around what exactly a binary file is. I've read links such as the below: https://en.wikipedia.org/...
Player_2's user avatar
1 vote
1 answer
50 views

Why splitted text files is bigger than a large one with the same content?

I have this large text file that when unzipped has about 2GB. I split this one into multiple(more than 5 million) files and now I have a folder of about 20GB, how is this possible?
Marcelo Machado's user avatar
1 vote
2 answers
266 views

Linked allocation in operating systems: why not use a doubly linked list?

I'm reading here that linked allocation uses a linked list, where each block has a pointer to the next block. For sequential access, this would take moving through the blocks one by one. Would it not ...
sprajagopal's user avatar
1 vote
2 answers
290 views

File systems and writing one

I am going through the following series of lectures on OS development . http://www.brokenthorn.com/Resources/ In the fourth tutorial , I came across the term " OEM" parameter block that stores the ...
Amigorust Burrough's user avatar
1 vote
2 answers
2k views

What is the file system of ram?

As much I know about a memory and storing data there would always be a managing type feature in every memory which manages all the data and its location. So, what is the file system of a RAM. I also ...
Vivek Ji's user avatar
  • 121
1 vote
2 answers
66 views

Meaning of "untyped bytes" in file systems

I am currently reading reading Chapter 11 of Operating Systems: Principles & Practice by Anderson and Dahlin, which speaks about file systems as abstractions for non-volatile storage. The ...
Then-Brief-864's user avatar
1 vote
1 answer
62 views

How can I prove the file on DVD is the original?

I have an old file written to a DVD-R several decades ago, and it turned out this file can potentially has some value as NFT (non-fungible token). The file was published online and have been copied ...
ivan866's user avatar
  • 111
1 vote
1 answer
397 views

What's the directory structure on disk that keeps the information of all files?

I'm reading Operating System Concepts by Avi Silberschatz(9thE), in chapter 11 File-System Interface, when the author explains the concepts of file, he states that The information about all files ...
Mengfan Ma's user avatar
1 vote
1 answer
92 views

Would this be the correct time complexity?

I'm currently working on an exercise that has made me ponder for a bit. The following exercise is from the 6th Edition of Data Structures and Algorithms in Java: An inverted file is a critical data ...
Tita's user avatar
  • 225
1 vote
1 answer
563 views

How pictures and videos are usually loaded in Memory? [closed]

Lets assume I'm talking about Jpeg and Mp4 and a general video player(not sure if different ones load it differently, if they do please tell) So do video players (process) usually load the entire ...
John P's user avatar
  • 750
1 vote
1 answer
51 views

How does symlink work?

I am recently studying The Operation System, I am confused about how symlink work even after watching some YouTube videos, hope there's someone can help me out with some questions. According to wiki, ...
Eric's user avatar
  • 17
1 vote
1 answer
54 views

Why has Windows used NTFS for 20+ years, while many different systems have trendend in the linux community over the same time?

I'm a first year MS:CS student, and my data structures class has inspired me to research file systems and their implementations. I recall using ext2, then ReiserFS, then ext3, then ext4, and now ...
nexus_2006's user avatar
1 vote
2 answers
141 views

Is a file a string of zeros and ones?

Is a computer file just a string of zeroes and ones? If so, can it start with zeroes? I have not been able to find an answer, surprisingly.
Alex's user avatar
  • 113
1 vote
1 answer
224 views

what does the author mean by directory structure in operating system?

I'm reading Operating System Concepts by Avi Silberschatz(9thE), in section 11.4 File-System Mounting, the author explains the steps of filesystem mounting as follows: The operating system is ...
Mengfan Ma's user avatar
1 vote
2 answers
116 views

Random file access in a block based file format

I am writing a program to store, retrieve and delete "blocks" of data of varying sizes. The way it currently works is by keeping a database storing the locations of the blocks and the locations of ...
Cedric Mamo's user avatar
1 vote
0 answers
20 views

How can I connect a drive to a 16 bit custom intel 8088 system?

I'm embarking on a long-term project, aiming to build a computer based on the Intel 8088 architecture. This venture provides an excellent opportunity to deepen my understanding of computer hardware ...
Grizzly's user avatar
  • 11
1 vote
0 answers
67 views

Is there any advantage to a hierarchical directory system vs. tagging files?

I've wondered this for some years now. As near as I can figure, if individual files were tagged with each of the components in a typical path (e.g. each of ...
Trev's user avatar
  • 296
1 vote
0 answers
43 views

Understanding Cyclic Dependencies when using Soft Update for Filesystems

We recently delved into the concept of "Soft Updates" as a mean of maintaining a Filesystem as consistent. The solution, as we learned it, calls for 3 basic rules: We'll create a pointer to a file ...
ITz's user avatar
  • 11
1 vote
0 answers
20 views

Custom version control

I develop an open source power systems software and I would like to include a simple collaborative mode so that more than one person could work on building a power system model. So far I have a table-...
Santi Peñate-Vera's user avatar
1 vote
0 answers
66 views

How to do atomic operations on systems that don't support it?

I need to sync data with WebDAV and other similar backend that do not have a concept of atomic operations. In some cases, I might need to read a file, change its content and write it back. And of ...
laurent's user avatar
  • 119
1 vote
0 answers
70 views

How do I implement fixed block storage file system in database from typical file-level file system?

I've a typical parent ID based file system in database and files are physically stored on disks. What I want is to store files in blocks (4096K) of fixed size. Chunking can be used I found, but how ...
Abhigyan Tiwari's user avatar
1 vote
0 answers
74 views

Algorithm for generating file systems

I'm working on an I/O generator program for a distributed file system. The problem I need to solve can be worded as a set of requirements: Reproducible (i.e. given some initial condition, the ...
wvxvw's user avatar
  • 1,388
1 vote
0 answers
53 views

Advantages of using a RDBMS

Apologies if this isn't the correct forum but I thought it would be too academic for the DBA forum. In my work I'm looking to research some of the benefits of using an RDBMS product over traditional ...
user5495269's user avatar
1 vote
0 answers
370 views

retrieve file format from unknown binary file [closed]

Is it possible, somehow, maybe by using some kind of brute force algorithm, to try and figure out what kind of file one is dealing with when one only has the raw binary without file format or meta ...
Michahell's user avatar
  • 111
1 vote
0 answers
28 views

Coordinate Systems in Files (pixels) [closed]

I'm trying to solve the problem of transferring data from a pdf file to another file type. When extracting data from PDF files I am to use the exact coordinates (where each unit is 1/72 of an inch in ...
Svetsi's user avatar
  • 111
0 votes
2 answers
969 views

Is it possible to wear-level a FAT32 file system?

Because SD cards use flash memory, they should requires wear leveling to avoid significantly shortening the life of the card. At the same time, my understanding is that they usually use a FAT32 file ...
Richard Dromey's user avatar
0 votes
2 answers
201 views

Why can't we mount multiple filesystem in same mountpoint?

Systems impose semantics to clarify functionality. For example, a system may disallow a mount over a directory that contains files; or it may make the mounted file system available at tha directory ...
Team B.I's user avatar
  • 263
0 votes
1 answer
154 views

WAV file header: Why 2 bytes for channel?

It is mentioned in 22 - 23 Number of Channels which will be 1 if mono, 2 if stereo. So why 22 and 23 (that is 2 bytes) allocated here? With 1 byte, we can put either 1 or 2.
Splendid Digital Solutions's user avatar