My 500 Gigabyt eSeagate external hard drive no longer allows me to access or copy files or subdirectories files. However, from the commmand propmpt (DOS mode in Widows XP) the dir commmand worlks listing files in the root subdirectooty as well as folders and provides the correct number of bytes left free on the drive )about 60 gigabytes. I have tried chkdsk on the drive but it cannot access the drive.Without any success I tried to recover data using select all copy and paste to a new external drive as well as xcopy from one drive to the other from the DOS c: prompt mode and also tried my computer backup program. I was only ablle to backup 100K of data before the backup was aborted. Are the remainder of the drives's contents salvageable? (The predominant error message given is an I/O (input/output) device error). This is a new development. Until then the external drive worked fine.
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In order to recover your data, I would suggest cloning your drive, sector by sector, using a tool that knows how to work around bad sectors (eg ddrescue), and then use data recovery software on the clone.
Ddrescue can perform multipass cloning. It clones the easy sectors on the first pass, and attempts the more difficult ones on subsequent passes. It can also clone your drive in reverse, thereby disabling lookahead caching. It keeps a log, allowing it to resume after an interruption.
It might be advisable to remove the drive from its enclosure and attach it directly to a SATA port on your computer's motherboard. That will eliminate the USB-SATA bridge board as a potential culprit, and will allow much faster data transfers.