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Re: copying large files between filesystems



Andrew Scott wrote:
Good advice. The disk isn't currenlty mounted and I'm running badblocks on it in read-only mode writing the output to a file. Interesting side note: the output file has been created but no bad blocks show up in it yet -- does badblocks only write on exit to the output file? Otherwise, perhaps it's just the drive controller or the SCSI card that are throwing errors and the data is safe and sound (oh, I hope this is true).

Ahh, you're using scsi?


Can you post excerpts from your kernel logs?

Yeah, run

hdparm -d0 /dev/drive


Excellent idea. I'll do this once badblocks finishes (looks like another hour). Though hdparm /dev/sda doesn't really return much along the lines of configurable options, I'll have to try this none-the-less. Thanks.

Sorry, this won't help with scsi... :(


and then:

dd bs=1 if=your-file-to-recover of=file-on-a-different-drive


Also, excellent idea. I was trying to read the filesystem blocksize of 4K. Totally stupid, I should go bit by bit!



Actually byte by byte...


I'll try these things next. Thanks for your thoughts. Excellent suggestions.

this will copy your file one byte at a time, creating more processing overhead which will slow you down.

Obviously, I don't know of any tools that rate limit file copying, except for maybe rsync, but I'm not sure about that either.


I emailed the guys at Namesys (reiserfs headquarters in Oakland, CA). They have a standing offer of "Ask any questions for $25". I sent them $25 and asked them a question. Hans Reiser got back to me as well as another employee, both with good suggestions. They suspected the hardware immediately. They made one really keen suggestion: if the bit count is identical on the original as the copy (when copied to another filsystem), but the md5sums are different, then try and run bindiff on the two files and use a binary editor to toggle the differing bits, with the goal of a correct md5sum match. I imagine this will the last thing



that's nice, but don't try that on the entire 2gb file, split it up first...



Good idea but how can I tell the split up files are actually good copies?

run cmp (compare) on the two files, it will tell you where they are different.


I try before sending the disk off for disk recovery.

Anyway, thanks a lot for your time and thoughts. What a pain in the ass.


Yep, anyone wonder why people like RAID?



Support your local student.



Use IDE, then people might consider that... ;)


Mike



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