Restore

A disk that I purchased new, and consolidated all my data to, actually ended up losing it's primary partition table and suffered from unknown other corruption and/or damage. Unfortunately, because real life has other demands and because I had a fairly recent backup and because I had undue faith in the drive, I did not have a current backup procedure in place to protect myself from data loss. So, I found myself investigating every known tool and technique for data recovery. The best tool I found was GNU ddrescue (manual)

root@hybrid:~# ddrescue -v /dev/sde /media/disk-a/backups/greg-laptop/recovery.img /home/greg/logfile

About to copy 160041 MBytes from /dev/sde to /media/disk-a/backups/greg-laptop/recovery.img
Starting positions: infile = 0 B,  outfile = 0 B
Copy block size: 128 hard blocks
Hard block size: 512 bytes
Max_retries: 0    Split: yes    Truncate: no

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:     8157 MB,  errsize:   1082 MB,  errors:   97884
Current status
rescued:     8157 MB,  errsize:    151 GB,  current rate:        0 B/s
ipos:   160041 MB,   errors: 298949447,    average rate:        2 B/s
opos:   160041 MB

Other tools

• http://safecopy.sourceforge.net/ - similar to ddrescue, haven't tried it yet, so it may give different results
• http://www.knoppix.net/ - liveCD that includes many of the tools you'd need if you don't actually have another linux system
• TestDisk from cgsecurity.org recommends ddrescue for corrupted partitions. Still, it and photorec are very useful.
• gpart can guess PC-type hard disk partitions, but couldn't read mine (b/c my disk is too corrupted)

Prevention

Maybe I should have used SMART Monitoring. The smartmontools package is what you need to install, plus the GSmartControl GUI if you're using a desktop system (instead of a server).