Hi, my roommate has a laptop with an 80-gig HD. He’s a fiend for downloading movies and music, and he likes to keep them and watch them repeatedly. So he’s got a hard drive full of movies and he had less than a gig free space.
I had told him he could have trouble that way, so he asked me to help. I removed some programs he wasn’t using, and deleted a few movies he didn’t want, and got the free space up to 3 1/2 gigs.
He’s got another 80-gig drive in an external bay that he wants to transfer the bulk of his movies to. But, whenever I try to cut (or copy) and paste a movie to the external drive, I get an error citing a cyclic redundancy check.
I know what that is, but I don’t understand it in this context. Can someone help me figure it out?
Sounds like a failing hard disk or external interface.
Here is a quick check - open a command prompt (cmd.exe).
do a cd to the source file (the one you want to copy)
type copy <filename> NUL
This attempts to read the source file and copy it to NUL (an empty device). If this works, the source is not the problem, and the problem is with the external drive or interface.
If it does not work, the laptop disk is failing, and you have to copy files individually to avoid those files that do not work. Then you will need some data recovery tools to try to get the damaged files off, if you can.
Could it be that the destination drive is formatted as FAT32, and the movie file being copied is larger than 4 GB? Bad combo. Make sure the new drive is NTFS (assuming we’re in a WIndows environment here).
The first thing to do is stop doing anything with that laptop. If the hard drive is starting to fail, it’s only a matter of time before it fails completely, and you don’t want to stress it any more than necessary. If you have another computer, shut the laptop down, remove the drive, and attach it to the other computer. That way the hard drive will not be used for swap space or anything else that might try to access it.
Then look into xcopy, which is a command line program that can copy entire directory structures and continue even if some of the files fail, and other data recovery tools. Start with the most important stuff. The drive really can fail completely at any time.
And then tell your roommate he got really lucky that this drive didn’t just fail all-at-once, and he needs to start backing things up
Also, can you plunk a bunch of normal-sized files on this new drive?
Try progrssively bigger files.
Is it only certain files?
Is the CRC-error on the destination, say when it tries to update the directory?
Does a CHKDSK of either disk give any errors?
It’s been a while since I tried it, but IIRC you get an error saying there isn’t enough space for the file. You don’t get a CRC error.
In my experience you only see CRC errors when either the source or destination drive has a physical problem (or someone has tried to get creative with some copy protection scheme).
Yes, doesn’t a CRC error during file operations mean one of the sectors somewhere on the file/disk/directory has a checksum (cyclic redundancy checksum?) error? Of course, another possibility is that the guy has downloaded zip or other compressed files, and the error is inside the zip file. Are you traversing down a series fo folders to find your file to copy? Did these movies ever play correctly, or is he simply trying to copy the internet to his hard disk.
cyclic redundancy check basically means there is a corrupt/unreadable sector in the file you’re trying to copy. means the file you’re attempting to copy can’t be read properly. If it can’t be read properly you really can’t do much with it. You can possibly read the data that is readable with certain software but what would happen is that the bad/corrupt part of the file would show in the copy. So if you manage to salvage let’s say the movie with the corrupt sector you’d watch it seeing at wherever the bad piece of data was seeing some garbage video somewhere in the video like odd colors the because the data was mangled from the original. This usually happens with cd’s and dvd’s because they are much more delicate mediums to store data so you should check them frequently because of disc rot or even markers can bleed through the layer of the disc causing damage to the data layer. It’s definitely time to replace the drive that has the error because that’s very rare for hard drives and when it does happen it means one thing, copy whatever you can from it right now because most likely more corrupt sectors will appear.
But unreadable sectors are at the disc level - they just happen to be where you are trying to read/write?
It’s also possible the error is on the target disk in the sectors of the target folder; since you also have to read/write that location (or the free space table, etc…)
Does it only happen copying one file? Or any file? Any file over a certain size? SOme files?
Good point about could be the drive your writing to it may be either or I believe. I would suggest a new drive though to be on the safe side because it is the disc that’s corrupt but sometimes and I would assume in any case what is causing it is the spindle and the spindle can create more.
A checksum is when you add up all of the bytes in a data element (ignoring overflow) and compare that to a stored result. In a CRC, you do more complex polynomial type math (in the computer this ends up being a series of simple shifts and divides, which computers can do quickly and easily). Even though the result isn’t really a checksum, a lot of people call it that. It’s a bit slangy and a nitpicker might give you a bit of grief, but there’s nothing wrong with it.
You could also call it “check value”, “CRC check”, “result”, or anything along those lines.
