Comments on: Unreported Disk Data Corruption – Kernel Bug?

By: John Goerzen

John Goerzen — Sun, 04 Mar 2012 14:33:17 +0000

I wouldn’t count on the boot-time memory test catching issues. It is not particularly thorough. Try apt-get install memtest86+, then reboot and select memory test from the GRUB menu, and let it run. See what it finds.

By: Rohit

Rohit — Sun, 04 Mar 2012 05:49:26 +0000

error correction:
I have to use “Win Vista” to download & to write them to cd/dvd

By: Rohit

Rohit — Sun, 04 Mar 2012 05:47:36 +0000

this happens to me too in debian/ubuntu…but same file works fine on Windows Vista on the same hdd…..I wrote to WD about this and they changed my hdd but the problem still exists…..this problem usually happens while copying….may be it is because of RAM problem but RAM successfully passed the test @ boot time…sometime I download files then it shows corrupted then I have to download it again and then it successfully extract that file….& iso file they always get corrupted in debian….I have to use visit to download & to write them to cd/dvd.

I posted this at debian forum a long ago: http://forums.debian.net/viewtopic.php?f=30&t=63313

By: Chow Loong Jin

Chow Loong Jin — Sun, 04 Mar 2012 05:45:53 +0000

If you’re getting errors in memtest86+, it would be best to replace your memory first, and then run a debsums later to see how it goes.

By: John Goerzen

John Goerzen — Sun, 04 Mar 2012 05:36:42 +0000

Thanks for the tips. Over on the G+ discussion, I got a similar one. https://plus.google.com/107171595803164194992/posts/TnxZM4agwuS I ran memtest86+ and got errors almost immediately. Yeow.

Now I’m debating whether to nuke my Debian install and restart from scratch. That’s a lot of time down the drain but might be worth it. I have no idea what could have been corrupted. debsums could verify my installed files, of course. I don’t have much in /home that would go unnoticed, or so I hope. and maybe some fsck’s would catch any fs issues. What do you think?

By: John

John — Sun, 04 Mar 2012 05:28:39 +0000

I had similar problems on a 6 month old machine.

Run md5sum 50 times on a file – get the same answer
Run md5sum 50 tinmes again – get 3 or 4 different answers
Tried running from tmpfs – same problem
Tried different fs, differrent disk – still happened
memtest didn’t find anyhting.
Turned out to be dodgy RAM.
Changed memory for new RAM, OK now.

By: Jim

Jim — Sun, 04 Mar 2012 05:25:54 +0000

Sounds like a hardware problem to me. You could try something like booting from a live usb and doing a md5sum of the full disk (while unmounted, ie. just the raw disk itself). Also check the usual culprits: ram (memtest) is probably the most likely. Try to figure out what the actual corruption is… Maybe with something as simple as ‘cp bigfile bigfile2; cmp -l bigfile bigfile2′.

By: John Goerzen

John Goerzen — Sun, 04 Mar 2012 05:17:05 +0000

Spoke too soon. I guess I had a respite, but now it’s all broken again.

By: John Goerzen

John Goerzen — Sun, 04 Mar 2012 05:11:25 +0000

Here’s an update. All of a sudden the problem went away. There are three things I did right around then, having given up for the day. One, I power-cycled the 802.11n router/switch/access point that’s about 2ft from the laptop in question. Two, I moved a different laptop, and three, I unplugged the Ethernet port. Oh, also I unloaded the VirtualBox kernel modules.

Putting all those things back where they were doesn’t cause the problem to recur. I can get the same md5sum on every run, and copying the file back produces the correct result.

However, I still have a corrupted file on disk. I can md5sum it and get the same result each time, but what’s stored isn’t correct.

Scary.