Access time versus Seek times

vbimport

#1

Hi all, have a quiestion that´s nagging me.

The manufacturers of CD-R(W) units often print down some specifications for the drives.
Now some of them use "Seek Time = value" while some use "Access Time = value", I was just wondering if this really is the same thing?

I´ve read somewhere that Access Time equals Seek Time + something... don´t remember what.

Please enlighten med :smiley:


#2

In my personal opinion :

Access time = The time needed to recognize the device

Seek time = The time needed to be at the beginning of a file on the device

In the opinion of the Seagate Glossary :

Access Time

  1. The time required to seek a location on a disc.
  2. The amount of time to read or write to a memory location.

Seek Time

The amount of time it takes the Read/Write heads to travel from their current cylinder location to a new cylinder and includes head settling time.

Of course the above defines the terms for harddisks and not cd-rom’s so i think the interpretation of my explanation would be more sufficient for cd-roms.


#3

Thanks for your input.

The thing is that it gets very confusing.
If you review a unit then i guess it´s really the access time that would be intressting.

Many manufacturers however specify the Seek Time and most benchmark program measure this value.
But then ofcourse some of them use the Access time instead.
Now, either they don´t know what they´re doing and just write down the forst word they can find or there is a big difference…

I hope you see my point.

So there should be a formula for calculating the access time when you have the seek time right?.. I´d like that formula.


#4

Originally posted by Chosen
[B]Thanks for your input.

The thing is that it gets very confusing.
If you review a unit then i guess it´s really the access time that would be intressting.

Many manufacturers however specify the Seek Time and most benchmark program measure this value.

But then ofcourse some of them use the Access time instead.
Now, either they don´t know what they´re doing and just write down the forst word they can find or there is a big difference…

I hope you see my point.

So there should be a formula for calculating the access time when you have the seek time right?.. I´d like that formula. [/B]

Yes and no… look at it this way…

If you have a normal cd (100% scratch free) the cd will be recognized in the given time and read flawlessly.

If the TOC of the cd is scratched , the cd could be very hard to be recognized , though files could be read almost flawlessly

If the cd is somewhere scratched , the cd could be very easily recognized , but getting files copied of it could give your reader a very hard time.

The thing is that the specs they present you usually are theoretic or ultimate numbers (“Why yes, our cd drive is 52 speed !” instead of "Our cd drive could read at 52 speed if you have a 700 mb cache and you only read this and this sector of it)

In common practice the overall usages is inserting a lot of various cd’s and rip or read them (there is a difference in ripping and reading as well !). You could check the various postings about ExactAudioCopy about that. The numbers don’t say much.

It’s far better to stick with the overall quality and in a review to test at least 20 times what the actual speed and performance is , instead of using nero cdspeed just once.