Issues with downloading files

**The Cog** · November 5th, 2012

That's an ugly problem. I have no idea why it might be happening, but if might be useful to know if it's a read problem or a write problem. If you campare the same pair of files several times, do you always get the same answer? If not then it's a problem with reading the files. If you always get the same answer then the error must have occured while writing the copy.

Can you mount the windows disk and try writing a copy to the NTFS partition instead?

You're not out of disk space are you? Try

Code:

df -h

and check there's enough space. I think this is probably not the problem because you don't see an out of space error, but it's worth double-checking.

**newuser1234** · November 5th, 2012

yeah it really sux as i'm learning linux and perl programming at the moment. as a beginner, i just assumed my programming really sucked (which it does but that's another story hahaha), but i realised that this is actually a real problem and that my code was actually ok.

based on your description cog, i'm assuming it's a read problems as copying the same file multiple times results in different errors -- sometimes none at all. as mentioned, copying files via winscp in windows 7 doesn't give these errors so i assume it's not a hardware issue. it's def. not a space issue as i get errors even when i have hundreds of Gb hard drive space.

it's a good idea trying to copy directly to the ntfs partition -- i'll try it tomorrow. from memory, i might have started on the shared ntfs partition (but copying using ubuntu and not windows), and actually i think i originally thought that the ntfs formatting might be causing these errors.

**The Cog** · November 5th, 2012

i'm assuming it's a read problems as copying the same file multiple times results in different errors

Copying the file involves both reading from one disk and writing to another, so you cannot tell which one is failing. That's why I suggested that you simply compare the same pair of files several times. If the problem is with reading then re-comparing the same pair of files repeatedly could produce different comparison results every time. If the problem is with writing, then re-comparing the same pair of files should consistently give the same result because comparing files doesn't involve writing.

**apollothethird** · November 5th, 2012

Newuser. I'm wondering what would be the results of copying/downloading files from a fresh try Ubuntu (with the OS run from the DVD)?

Boot to the DVD, then run the same scp, cp, and cmp commands and see if you get the same. If you get the same, this might indicate a problem with your hardware (ram, motherboard, harddrive). Try first running copies to the ram drive space. Then mount your local drives and try transfers to it.

If you have success, it might indicate some problem with your OS installation.

-- L. James

--
L. D. James
ljames@apollo3.com
www.apollo3.com/~ljames

**newuser1234** · November 6th, 2012

That's why I suggested that you simply compare the same pair of files several times.

ok, i just realised what you meant. you and apollo have given me quite a few things to chase up, and given the randomness at which the copy issue arises, i'll need to spend more time on this over the weekend using different copy configurations ie. between hard drives and between partitions. i just realised that this issue also occurs in windows as 1 file copied by winscp seems to have a copy error. it seems to occur much less frequently using winscp, and the error introduced is much smaller. ie. ubuntu scp issues results in the introduction of many (off the top of my head >30) lines of text from other files on my hard drive into the copied file, whereas the windows copy error (using winscp off a server) results in the introduction of only 1 line of text into the copied file.

i brought the laptop into repair (still under warranty) ~ 1 month ago for constant bluescreens in windows. the repairers said they didn't experience any bluescreens during their tests, but they replaced 1 of the ram modules anyway (the one they upgraded for free during the purchase). since then i don't get any windows bluescreen, so i'll see if i can get the other ram module replaced on the weekend as well. will keep you guys posted on the weekend --unless the repairers want my laptop to do more testing on it.

**The Cog** · November 6th, 2012

I think the live CD gives you an option of running a memory test instead of booting into Linux. That might be worth running for a while.

**newuser1234** · November 6th, 2012

thanks cog -- i'll def. give this a go. looks like i'm in for a busy weekend!

**newuser1234** · November 10th, 2012

ok, so i copied 3 files (~5 Gb each) 7 times (21 copies in total) in windows from my hard drive to my laptop hard drive with no errors in any of the copies. seeing as it's difficult to reproduce this copy error in windows, and that my warranty only covers windows issues, it looks like i won't be able to return it for repair. it's possible that the file that i thought was copied via windows and which had an error might not have been copied in windows -- i've done so many copies that i can't remember properly.

with re. to checking whether cmp gives the same results each time, i did a copy in ubuntu (hard drive to laptop), then did cmp between the two files 5 times, each one reporting the same error. i also did a memory test and it came back as ok.

i also booted ubuntu from the installation dvd and ran it under the dvd. i then did 3 copies and 2 of these resulted in an error. i think it's time to put this in the too hard basket. luckily i can copy the files i need through windows and work on it in ubuntu if needed. i also have access to other computers that i can check scripts on so i'm not too worried. hopefully, future ubuntu updates might be able to fix this issue. anyway, many thanks to cog and apollo for troubleshooting this with me -- much appreciated!