I'm Amazed: How Do Hard Drives Simultaneously Perform Different Tasks?

  • Thread starter Thread starter peter.ell
  • Start date Start date
  • Tags Tags
    Hard Work
Click For Summary

Discussion Overview

The discussion centers around the operational capabilities of hard drives, particularly how they manage simultaneous tasks such as reading, writing, and deleting files. Participants explore the mechanics behind these processes, the implications of multitasking on performance, and the effects of system architecture on hard drive functionality.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how hard drives can perform multiple tasks at once, suggesting that the speed of the read/write head cannot account for simultaneous operations.
  • Another participant explains that hard drives can have multiple read/write heads, allowing for some concurrent operations, although they note that deleting files does not involve physically altering the data.
  • Some participants mention that quick actions are often handled by RAM, with hard drives being used for less time-sensitive operations.
  • Discussion includes the impact of seek times and RPM on hard drive performance, with references to caching techniques that enhance data transfer rates.
  • One participant raises concerns about the performance impact of multitasking on hard drives, particularly when burning DVDs while accessing other files, suggesting that this could lead to interruptions.
  • Another participant clarifies that hard drives cannot perform multiple reads simultaneously, and that random access can slow down data rates.
  • There is mention of the importance of buffering in data processing, with references to how software manages data flow between different components of a computer.
  • A participant expresses concern about the potential wear on hard drives from excessive head movement when accessing fragmented files.
  • One participant notes that the technology discussed may have evolved since the original posting, implying that some information might be outdated.

Areas of Agreement / Disagreement

Participants express a range of views on the capabilities of hard drives, with some agreeing on the limitations of simultaneous reads and writes, while others present differing opinions on the implications of multitasking and performance. The discussion remains unresolved regarding the best practices for using hard drives under multitasking conditions.

Contextual Notes

There are limitations regarding the assumptions about hard drive technology and performance, as well as the dependence on specific system configurations and software capabilities. The discussion also touches on the potential impact of fragmentation on hard drive longevity, which remains a point of contention.

peter.ell
Messages
42
Reaction score
0
Actually, I understand the basics of how hard drives work, my question is more specific. I'm curious as to how a computer's hard drive can simultaneously delete files, read files, and download files all to/from different places on the hard drive.

It can't just be due to a fast-moving head, it can't possibly move fast enough to do all those things for multiple files at the same time, right? If it can, how in the world did engineers get a hard drive to read and write to many different places so quickly?

Our ability to create things just boggles my mind!
 
Computer science news on Phys.org
peter.ell said:
Actually, I understand the basics of how hard drives work, my question is more specific. I'm curious as to how a computer's hard drive can simultaneously delete files, read files, and download files all to/from different places on the hard drive.

It can't just be due to a fast-moving head, it can't possibly move fast enough to do all those things for multiple files at the same time, right? If it can, how in the world did engineers get a hard drive to read and write to many different places so quickly?

Our ability to create things just boggles my mind!
It helps that the read/write head actually has multiple heads. They all move in unison, true, but one can be reading while another is writing.

Beyond that, though, yes. They are just incredibly fast.

You can read a little about it: http://en.wikipedia.org/wiki/Hard_disk_drive#Data_transfer_rate

BTW, they actually only have 2 actions: read and write.
Deleting is simply removing (overwriting) the pointer to the file. It doesn't actually touch the file.
Downloading is not a hard drive thing. That's a network thing.
 
Last edited:
Most quick actions are done from within RAM where there are no moving components. Then when speed is not so critical it writes to the HD. However most HDs are now at least 7200RPM which is quite fast.
 
DaveC426913 said:
It helps that the read/write head actually has multiple heads. They all move in unison, true, but one can be reading while another is writing.
Hard drives, at least the ones used on PC's don't do that anymore. Because of the high track densities and the fact that servo patterns are created by other devices, the tracks from surface to surface are no longer lined up. It takes longer to switch heads and reposition the head to track center than it does to step across a surface by 1 track and recenter the head.

With average seek times at 10ms or less, and at 7200 rpm (or in some cases 10,000 rpm), the total seek time isn't too long and the drives can random access fairly well. There is also read ahead and write behind caching going on in the drives and also in the computer (depending on the OS). The main improvement has been in streaming transfer rates because of the increasing bit densities.
 
This is one is good also. The narrator explains what's going on.



This one explains the action at the head level with Flash/Java demos on the right

http://www.research.ibm.com/research/gmr/basics.html
 
Last edited by a moderator:
Besides how this mechanism works, I have another question about reading two or more files simultaneously from a hard drive.

Isn't this bad to burn a DVD from an HDD and at the same time try to open different files and listen to music and ... from that same drive?

I say that because when I'm burning a DVD from my external drive and try to play a video file or copy from my HDD at the same time, the Writing Buffer decreases to zero or the video files I try to play have little interruptions when playing.

I don't think it's because of my system components. my external HDD is USB 3.0 and I have Windows 7 HP and a Dell XPS 15 L502x with Core i7 and 6 GBs of RAM and my burning software is Nero which is a professional tool. Is this normal?

I'd be very thankfull if someone could help.
 
cheraidnist said:
Besides how this mechanism works, I have another question about reading two or more files simultaneously from a hard drive.
A hard drive can't do multiple reads simultaneously. It's reading data from one location at a time. It can anticipate further reads from that same area later with read ahead buffering to reduce the amount of random accessing. A hard drive's data rate is much slower if it has to do a lot of random accesses.

Isn't this bad to burn a DVD from an HDD and at the same time try to open different files and listen to music and ... from that same drive?
Depends on the data rate required to burn the DVD versus the effect data rate of the HDD if it's doing a lot of random accessing, but yes, it's probably a bad idea. The DVD burning program should set it's priority higher than normal (you can check this with task manager), so that the music or video would get interrupted, instead of the DVD burn process, which I think needs to be continous. If you have multiple hard drives, then burning the DVD from one hard drive while watching a video from a different hard drive should not be an issue.
 
Thanks a lot rcgldr. i hope it would be helpful to use priority options of task manager. There is also some third party software from Microsoft that does the task more professionally, i do not remember the name.

About reading two files at the same time, which is not exactly a simultaneous read action as was mentioned in previous posts, i think even if the read rate is not high, it's not a good idea to do this, specially if the hard drive is fragmented. because Drive Head should move between sectors so many times to read and buffer a file in one place and go back to read and buffer the remaining of the other file and so on. Since HDD life expectancy depends specifically on Drive Head moves, i think it will reduce the life span very much.
 
  • #10
Buffering the right thing at the right time can do wonders. That's part of the so-called "mystery".
That's a technique you'll encounter EVERYWHERE in the business of processing data. For instance your DVD burn software probably buffers some amount of data from the slower access HDD to your RAM. Browsers buffer data from the slower internet medium to the faster local HDD. Your processor buffers data from the slow RAM(comparatively) to its own fast registers.

And this piece of software you are referring to doesn't do it "more professionally", it just gives you more information and looks fancier that your average task manager.
It is also called "Process Explorer" and is an incredible piece of software for monitoring just about everything your computer is doing in real time.
 
  • #11
Sorry, this thread was originally posted almost two months ago. The technology has changed. All answers are no longer valid.
 

Similar threads

ArsTechnica Article on Backing Up Your Stuff via BeeStation
  • · Replies 6 ·
Replies
6
Views
2K
How can I protect my flash drive from reformat?
  • · Replies 5 ·
Replies
5
Views
2K
Find Free Software to Log Disk Usage & Monitor Processes
  • · Replies 30 ·
2
Replies
30
Views
4K
How do encrypted USB flash drives work and how can we make them more secure?
  • · Replies 7 ·
Replies
7
Views
3K
Can a Universal Drive Adapter Help Preserve Data from Old Hard Drives?
  • · Replies 11 ·
Replies
11
Views
4K
Fixing My Hard Drive: 2002 - 2009
  • · Replies 3 ·
Replies
3
Views
3K
[Ubuntu] Why is my computer slow (jk, but seriously )
  • · Replies 10 ·
Replies
10
Views
6K
How do I format my hard drive and reinstall Windows Me?
  • · Replies 4 ·
Replies
4
Views
4K
How Do Our Brains Process Tasks Differently?
  • · Replies 5 ·
Replies
5
Views
3K
High School Difference between special relativity and redshift?
  • · Replies 11 ·
Replies
11
Views
2K