Cyclic Redundency...

[bear]

So I've been transfering some files from my laptop to my external hard drive and every once in a while it says "cannot copy file (cyclic redundency check)" or something like that. It also said this once I downloaded the Cannon Fodder set Cleantone just put up. What does this mean? Do I have a virus? or something f*ed with my computer.

[harrymcq]

It means your data is corrupted, probably because your hard drive is failing. Do you have a current backup? If not copy the stuff to another drive ASAP. I'm guessing you have Windows from the type of error so I'm not too much use troubleshooting it further, you probably could run some utilities. I'd either google it or get it into a repair shop right away.

[bear]

thanks for tip Harry. fucking windows...

[harrymcq]

Well as much as I would love to pin it on Windows it is probably just a hard drive failure which would happen if you were running Mac OS or Linux as well.

[bear]

How about Dell? can I blame it on them? Ha!

thanks for the help harry. when I downloaded some recent white thighs recordings from senduit.com (single tracks only not zip files) it worked fine. not sure what the story is. I'll get my shit checked out fo sho

[Phrazz]

First of all, hard drives are mechanical devices, and anything that moves will break down faster than something that doesn't move (like solid state). Bit errors are common on disks and hard drives slowly "lose their minds" over a period of several years. After five or six years, the bit lossage can be too much for the compensation mechanisms to help anymore. All magnetic (and even optical) media has a shelf life, just like food (more like canned food). Optical of course has a longer shelf life, but it's still not perfect.

A Cyclic Redundancy Check is a "checksum method" used to protect against "noise" (errors) in the data stream. This basically adds strategic bits or bytes to come up with a unique checksum that's used to verify whether all bytes or bits that are in that chunk are happy. To an extent, small CRC errors can be fixed by altering the output data stream using certain error-correction "tricks" (black magic). With audio, CDs use these thousands of times a minute and we never even detect this with our primitive human hearing (though a bit comparator will illustrate the mistakes). When they are "too tragic to recover", we hear pops, clicks, skips and other audible defects in the sound stream.

There is software which can help copy files that fail CRC checks, but that also means it's going to make "best efforts" to fix the data and that may result in some data loss even though you get the file back most likely in one piece (better than none of it, right?).

http://www.wikihow.com/Copy-a-File-and- ... eck-Errors
http://www.newfreedownloads.com/find/ca ... check.html

As the surface of a hard drive keeps flaking off, over time it will be rendered useless. This is also directly proportional to how heavily it is used, which is why drives have MTBF specs which are calculated from extensive statistical analysis. When your drive is near that MTBF, is is nearly "guaranteed to fail" by the laws of probability. When your CRC errors are becoming a headache, time to get a new drive and start making a full backup (using data recovery tools to get the bad files over after you've tried all the good ones).

O/S will mark bad sectors on disks that have too many errors to be used. Even brand new hard drives have bad sectors, and these get mapped out during format time. If a new drive has too many bad sectors, it won't format at all...but this "bad sector ratio" is hard to find and is a general indication if the drive will be able to perform above or below the expected MTBF (we can talk about what Mean means, but that's esoteric).

In any case, before you pin yourself to the wall, get another hard drive and start copying the stuff you care about the most. Flaky drives go from a little flaky to completely hosed in very little time with little warning...that is just the nature of those beasts. Which is also why moving spinning disks are going the way of the dinosaur and in five or ten years will be museum pieces. We can already see CDs starting to become obsolete (as iPods and solid state devices take over in efficiencies of space and speed).

Also, audio and video tend to stress hard drives a lot more than usual data use (like for files, documents and less dynamic data). That greatly increases the media burn rates.

[bear]

thanks for the insight. i think it might be time for a new hard drive.