Questions tagged [filesystems]
Questions about algorithms and data structures for storing, organizing, and naming data in durable storage systems.
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How to know size of header of a WAV file
It will help to know how to figure out the size of header of a WAV file by looking at its byte structure.
Source: http://soundfile.sapp.org/doc/WaveFormat/
UPDATE:
On second look, it says ...
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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 ...
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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.
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Where is File Allocation Table in FAT32 file system stored?
I had been reading about File systems recently and came across the File Allocation Table in FAT systems. As per my understanding the File Allocation Table contains entries of the various files stored ...
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Compression Gzip/7Zip
When I calculate the entropy values of files compressed with Gzip, PKZIP, 7ZIP and Winrar, I find that the compression rate of Gzip is higher than the others. The entropy value is higher (indicating ...
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Bidirectional links in file systems?
Typcial links are unidirectional, which has the drawback that the link
will point to invalid if its target is moved or deleted.
Bidirectional links would provide the possibility to update.
Moreover: ...
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Write-Ordering Problem, Idempotency in Distributed File Systems
I have recently finished reading the section on Distributed Systems in OSTEP. For NFS, they briefly mention the cache consistency problem and say how it is solved for reads by maintaining an attribute ...
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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 ...
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Concept of a Stream Device
In class, professor mentions that there are Stream and Storage devices. I mean to ask about Stream devices. I've also heard the terminology character devices.
On a Linux VM, the corresponding terminal ...
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Difference between Distributed File System, Cluster File System and Parallel File System
On the internet, I am unable to find concrete definitions of these three types of file-systems. Can someone clearly explain the difference between these?
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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 ...
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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 ...
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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, ...
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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 ...
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How can computers tell where the beginning and end of file/packet/frame headers are?
I'd like to know how a computer can determine the beginning and end of certain file components (attributes, headers, frame/packet/segment headers etc.) when these components can be omitted or added in ...
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File conversion to binary format to save storage space
Our test log files are stored in .asc format. Each file contains around 5000 rows of these Logging Strings as shown in the image. I would like to reduce the size of these files.They are around 4-5 MBs ...
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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 ...
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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 ...
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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 [...]&...
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How to study in and outs ofOperaring Systems
I want to study operating systems in depth, in particular windows, linux and android OS. What is the best way to get started?
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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 ...
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where to get detailed information about some file format?
i want to learn about the structure of a .blk file but the problem is I don't know where to look for detailed information of this sort, most of the google searches I made gave me links to viewers.
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Where to learn about filesystem file placement strategies?
I'm facing a task similar to what filesystems do. I have a bunch of continuous allocated space and I need to place pieces of variable length data into it, each piece of data can change size over time....
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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 ...
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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 ...
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Renaming of linear list directory
Consider a linear list-based directory implementation in a file system. Each directory is a list of nodes, where each node contains the file name along with the file metadata, such as the list of ...
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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 ...
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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 ...
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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.
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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 ...
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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 ...
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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 ...
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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-...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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magnetic Disk Calculation
A magnetic disk has 1000 cylinders, 10 tracks per cylinder, 128 sectors per track, ...
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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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