CD-RW access times

  johnnyrotten 12:33 24 May 2004

I raised a topic here some time ago but I thought the problem was under control and I now seem to have lost the thread.
The situation is this.
I have a four year old desktop (450MHz Pentium, Windows98, 128MB RAM, CD/DVD reader, CD Writer, etc.)
For the last few years I have been backing up data to rewritable CDs. I have four top level archive folders, each with many files and sub-folders. Their sizes are all between 460MB and 500MB. They are now on seven discs, from four different brand name suppliers.
On my desktop I can recover each of the archive discs in between four and a half and seven and a half minutes. The variation (maximum time minus minimum time) for any one disc is less than a minute.
On a number of different machines I get between three and a half and seven minutes, with maximum variation of about one and a half minutes for any one disc.

So far, so good. The archive and recovery system works.

I recently (last October!) bought a new laptop computer (2.6GHz, WindowsXPHome, 512MB RAM, DVD reader/CD reader/writer combo etc) and the first thing I am trying to do is to recover my archived data reliably from the desktop machine using the CD-RW discs that I know work.
At first I was getting one and three quarter hours per disk. The computer supplier looked at it for a month and produced a written report saying there was nothing wrong with it. When I asked them to demonstrate its operation, they immediately saw and acknowledged a problem. They kept the machine, and a disc that provoked the problem, for another month and then told me they had fixed it and it now read in under ten minutes. When it was returned to me I immediately tried it out again and this time I saw over two hours i.e. they had made it worse.
After much effort on my part they eventually replaced the machine with, allegedly, a brand new one (and 2.8GHz to boot). When they eventually delivered that and demonstrated it, last thing on a Friday evening, we only had time to try two discs, at sixteen and thirty three minutes. I said I was very disappointed with the performance but the engineer said he was not surprised, it seemed acceptable to him.

I have since then tried many times (about fifty transfers) and am seeing inconsistent and non-repeatable results for all discs of between four minutes and well over one hour. When I immediately repeated a read from one disc that took over an hour, it then worked in five minutes.
I now know the laptop can read each of the discs in less than ten minutes.

Questions for your readers and any experts out there:
What is the maximum time I should expect to read about 490MBytes from a working CD-RW?
Why do the times vary so much from minute to minute?
Is over an hour acceptable to read less than one CD's worth of data? If not, then what could possibly be wrong?

  Fruit Bat 15:40 24 May 2004

How fast a CD can be read depends on the read speed of your drive ie 52read 16 write 8 rewrite quoted in the manufatures manual

A whole CD should be readable in a few minutes.

What slow things up is when the quality of the disc is poor and the software is constantly searching for the contents of a file. CD-RW discs are renown for rapid detioration and should not be used for storing valuable data over long periods ie months. you did right in archiving to several different brands but wrong in using CD-RW use CD-R as discs are now very cheap 50p each.

  johnnyrotten 17:21 24 May 2004

thanks for the advice.
As you said, a whole CD should be readable in a few minutes and, yes, they all are, even on teh laptop. My problem/query is that there is SO MUCH variation on the laptop when I know the discs are readable in a consistently low time on other machines.

As for CD-Rs, ok they are cheap now, but I think archiving to four or five once or twice a week, with duplicates for security, could still mount up to some hundreds of pounds a year.

When I feel I can trust the system I might even go for an external hard drive or two, that looks cheaper.

But baasically, why would/should a number of old desktops be so consistent with the same CD-RWs when compared to a new laptop?

  Fruit Bat 22:05 25 May 2004

All sorts of factors affect readind of CD especially CD-RW, Spin speed, height of disc above laser, type of laser, power of laser, even the package writing sofware the data is written with INCD etc. Unfortunataely the best CDROM to read the disc is the one you used to write it.

  johnnyrotten 17:17 14 Jul 2004

to Fruit Bat
thanks again.
I think I appreciate all the factors you mention but still dont understand why reading the same data from the same disc on the same computer via the same drive can vary from day to day between 5minutes and 75minutes and back again. And even with a CD actually written on the same drive I have so far seen variation from 5minutes to 40minutes.

It is the VARIATION and INCONSISTENCY that really bothers me.

What is the MAXIMUM time one should expect to read 500Megabytes of assorted data files from CD to Hard Disk via a 24xRead CD drive? Is there no specification to rely on?

  confused_alan 19:00 16 Nov 2004

change of name, change of tack.
I have a CD-RW with about 780 files, 490 megabytes of data.
The whole data can be transferred via three different machines consistently and repeatedly in five minutes, give or take half a minute.

On my laptop it can take between five minutes and well over one hour.

My laptop supplier now claim that such variation is "feasible".
However, they do not seem to be able to grasp that I am doing exactly the same thing over and over again and getting different performance with their machine. They now say that "what is reasonable ... is subject to the operations being carried out."They keep ignoring that the "operations being carried out" are exactly the same.

But at least now we know. Over one hour IS feasible for data that is known to take five minutes. Why do we not read of this apparently well-known performance inconsistency in your magazine?

Can any of your readers, or your staff, shed any light on this?

This thread is now locked and can not be replied to.

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