Best practice for bulk data transfer

[James Wilkinson]

Andrew wrote:
> Procedure 2: The faster option (repeated for each hard drive)
> 
> [slow server] halt
> pull hard drives off slow_server and place in removable tray on
> faster_server
> [faster server] dd if= /dev/slowdrive ibs=4096 conv=notruc,noerror >
> slowdrive.img
> [faster server] mount slowdrive.img && calc md5sums > list
> [faster server] rsync /mnt/slowdrive/ /newdir/
> [faster server] cd /newdir/ && check md5sums against list

> Questions:
> 1) Theory question: will Option 2 produce identical results to Option 1 only
> quicker ??
> 2) Practical question: is Option 2 "too risky" given the age of  the drives
> ?? I have this fear of possibly harming a hard drive no matter how careful
> .. is my fear justified or baseless ??

I'm guessing you don't have recent backups of the slow server -- whoops!
I'm also guessing that the data on the drive is fairly valuable.

Personally, I wouldn't risk Option 2.

If you're trying to minimise downtime, how about:
 * md5sum all the files
 * Transfer them *all* while the server is in use
 * Stop people using the server, and do a
    find $PATH -xdev -type -f -mtime -3
   to find all files that have been modified in the last couple of days.
   Move just those files.
 * Run md5sum on the new and the old server to check that nothing has
   changed.

James.
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