Computer Science

Questions tagged [filesystems]

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

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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 ...
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23 views

What could happen if bitmap and data block not updated

Learning some exam questions, got stuck on this one, hope someone can help me out. Assume that we have simple file system without a journal where we write directly to bitmaps, inodes and data data ...
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43 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 ...
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14 views

Calculate for each block, the number of bytes that can be assigned to data and to pointers to other blocks

In trying to solve the following problem: You are presented with the first 15 blocks of a secondary storage device (disk) which has a total of 30000 KB available. The linked allocation method is ...
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2answers
44 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 ...
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1answer
23 views

No. of disk blocks writes required for writing the file

Assume that a file is written using write(fd, buf, K) system calls, where fd is the file descriptor, and K, the number of files to be written to the current file offset which is a multiple of the disk ...
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1answer
343 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 ...
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1answer
159 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/...
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19 views

Where are file-information like “created” or “last edited” actually stored?

I can access some information about the files ("created" or "last edited") on my PC. But where are those information actually stored? Are they stored by the operation system? Could be possible as if ...
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1answer
97 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 ...
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1answer
267 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 ...
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2answers
96 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 ...
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48 views

How are files managed in a filesystem?

I have recently been interested in low level computer science (as a hobby), and I have just learned about the way a computer organizes and stores information on a hard drive. I have learned the basics ...
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1answer
109 views

Source code for Network File System [closed]

I am doing a small project which explains how operations (file open, file write etc.) are done in client side and server side in network File system. Can anyone help me out providing its source code ...
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1answer
83 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. ...
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2answers
146 views

On what abstraction is a filesystem actually built on?

Data is read in terms of a block from a storage device(magnetic, optical, flash). Size of the block depends upon the filesystem and os. The physical device may have different units of storage like ...
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348 views

magnetic Disk Calculation

A magnetic disk has 1000 cylinders, 10 tracks per cylinder, 128 sectors per track, ...
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1answer
34 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?
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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 ...
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2answers
736 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 ...
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67 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 ...
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51 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 ...
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1answer
1k 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 ...
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1answer
71 views

What happens under the hood when the process requests operating system to open a file?

Suppose a process wish to open a file named test.txt. So it issues a system call requesting Operating system to find the file on disk,and to grab the handle of file to operate on it. My question is ...
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3answers
443 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 ...
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1answer
21 views

How a file is determined [closed]

If I have the integer ""1234" stored in a file, the size of the file when I use the command "ls -l" or "wc -c" is 5. If I have "12345" the size of the file is 6. Basically the number of bytes in a ...
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221 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 ...
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1answer
1k views

Deleted data remains on a disk until? [closed]

I am little bit confused between the two answers below. What is the exact answer of this question? My query is, "Deleted data remains on a disk until...?" The data is overwritten; The recycle bin is ...
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1answer
46 views

How to parse data in a text file? [closed]

I had a question about altering a text file. I have data in the following format. 1 a,b,c 2 d,e 3 a, l, m,n Note that some of them have spaces after the coma ...
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2answers
752 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 ...
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24 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 ...
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312 views

What are disadvantages of a Operating System that recognise file extensions ?

When Operating system recognise the file types It has several advantages like 1. avoid mistakes like trying to print a object file that produce garbage output but I can't think about disadvantages ...
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1answer
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 ...
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1answer
72 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 ...
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1answer
33 views

Can file snapshots aid in detecting malware?

I noticed certain programs have a feature that can have a 'snapshot' of a file from a certaim time and compare it to a more recent snapshot of the file. If one's system has a snapshot of a program ...
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2answers
6k 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 ...
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1answer
65 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 ...
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1answer
869 views

Maximum possible file size in the filesystem [closed]

A file system with 300GByte disk uses a file descriptor with 8 direct block address ,1 indirect block address and 1 doubly indirect block address. The size of each disk block is 128 Bytes and the size ...
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1answer
26 views

How to name documents in windows? [closed]

What is the best way to name documents and folders in windows? Im thinging about maybe there will be some conflict in some programs? Or when searching in terminal This_Is_Best.doc ThisIsBest.doc ...
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1answer
1k 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 ...
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2answers
74 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 ...
2
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1answer
65 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 ...
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2answers
239 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 ...
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1answer
95 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 ...
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4answers
213 views

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 ...