Backup question (more or less)

[tonyvella]

This is a silly question, hence the subject line!

I have a built-in slot for an SD card in my laptop with an SD card in it. I have some 500 pictures on my hard drive which I wish to copy onto the SD card. When I start the copy process I get:
8 hours remaining - 30 seconds later it changes to:
2 minutes, 45 seconds remaining - 20 seconds later it changes to:
less than one minute remaining.
and bada-bang, the job is done in less than 2 minutes.

My question (idiotic, I know) but how the heck does the computer estimate the original 8 hours anyway? Even my lawyer's estimates of his fees are closer to his final charges than that: 8 hours to 2 minutes.

 

[Lady Fitzgerald]

I get the same thing. I don't how the computer estimates time remaining but I've learned to ignore it. If I'm moving a large amount of data, I just start it, then walk away to do something more important, such as a bathroom break, fix and eat a snack, go to bed, etc. depending on how much data is involved. It's not worth worrying about.

 

[Alejandro85]

Mandatory xkcd comic about the subject.

The related explain xkcd entry gives some light on why such things happen:

This is because Windows bases its estimate on the latest file transfer rate, which exaggerates short-term fluctuations

Which is totally reasonable based on everything we see with such file copies. That behavior would only make sense when copy goes at a constant speed, which rarely happens in practice.

Bottom line, if you want somewhat accurate estimates, you must use a serious file manager or copy program and not Windows Explorer.