This is complex to describe with lots of variables. I'll try to note everything without too much extraneous detail, but my apologies in advance if I'm on the wrong track.

My backup disk is in a Vantec external dock. This dock allows me to connect either with eSATA or USB.

I use a simple, basic backup program called Karen's Replicator to do my backups. All it does (as I have it configured) is make the backup drive look like the source drive, copying/deleting files as required. Let's not get into whether or not this is an optimal backup strategy; for my non-mission-critical data it suits my needs: I don't have old versions of files I might need to retrieve, and I rely on the Recycle Bin should I delete a file in error. Simplicity is my goal here.

There are 36,398 files on the source drive, each file about 52MB. My preference for backing up is eSATA. On my hardware, it runs about 4.5 times faster than the USB connection. However, sometimes my eSATA connection is unreliable. Most recently...

I ran a backup Saturday morning. Or at least, attempted to. As sometimes happens, the eSATA mode gave trouble, locking up the computer after about 80GB of transfer. Nothing short of a hard power-off reset will bring it back to life when this happens. No mouse, no keyboard, nothing except the power button on the tower case has any effect. I tried again with eSATA, same results. So I unplugged the eSATA cable on the external dock and plugged in the USB. A quick check with Windows Explorer to see how much data had been transferred showed the above mentioned 80GB. The remaining 1,767GB (yes, GB of data that used to be on that 1.81TB drive were just... gone.

I thought I would start up the Active@ Hard Disk Monitor program and look at the operating information for the hard drive(s), not that I would have understood much of it, but instead got a "Not Connected" error. (See screen shot.) Hunh? Could it be that I can't start that program after the computer is booted up, but must have it in my Startup menu instead?

Oh well, unpleasant surprise, but at least the source data, on an identical WD-20EARS 2TB drive was intact, so I started the backup again with USB. A day and a half later, it was finished. And the destination (i.e., backup) drive had about 73GB less data on it than the source drive. A check of the backup log showed that a big chunk of files right in the middle of the job couldn't be written to the destination drive for various reasons. Re-running the backup again generated a similar backup log. Several times re-attempting the backup it would lock up on the same file, the one shown at the beginning of the error list on the attached log. Just to be thorough, I decided to go ahead and lock up my computer again by connecting the destination drive to eSATA instead of USB. The computer went bonkers (technical term) the moment I turned on the power to the external dock. The "Start" menu would only show as long as I held the mouse button down. Windows Explorer would come up with a blank screen "Application not Responding". At least the keyboard worked, so I was able to kill the Explorer with Task Manager. So I gave up for the night.

Earlier I had tried different backup software (FBackup4) with similar results: After backing up some files it locked up the computer.

This morning just to be sure it was broken, I tried USB again, which is when I generated the attached log file. Because I am a masochist I thought I'd lock up the computer again with eSATA, figuring that maybe it would catch on fire or something and give a few more clues as to the problem. Instead it did something worse: it began backing up the missing files at 4.5x the USB speed, running perfectly, doing exactly what it was supposed to do. As I type this it is about 90% done copying over the missing files.

So, do I have a hardware problem? If so is it the hard drive, the Vantec dock, the cable connecting the dock to the back of the computer, the eSATA connection from motherboard to back of the tower case?

Would things be happier if I reformatted the hard drive and started over from scratch?

Is my backup software (which has worked quite satisfactorily for the last eight years or so) the culprit?

What should I do now?

Addendum: The backup finished, and depending on just which disk statistics I look at, it is either perfect or there is as much as 5GB discrepancy somewhere.

Attached is a very elaborate screenshot showing disk information after the backup. It is too big to display automatically with the post, so you'll have to open the attachment yourself. F: drive is on top, L: drive on the bottom. L: is the backup or destination drive. The gray data boxes are from left to right Properties of the whole Drive; Properties of all the folders in Root; and Properties of just the "Library" directory, as shown by Windows Explorer. The right half of the whole screenshot shows (you're way ahead of me here) the actual Explorer windows. In the lower right corner of the screenshot is a brief spreadsheet with all the pertinent data from the gray boxes, arranged in a compact and easier to read format.

According to Windows Explorer, of the three folders in the Root directory, two are empty ($Recycle Bin and System Volume Information) and the Library folder is the only one with data. I find it encouraging that the Library folders (green highlight) in the F: and the L: drives match exactly, both in number of bytes and in number of Folders/Files. This would suggest that the backup was successful.

However, I am puzzled by the discrepancies in overall disk statistics. At the Drive level (pink highlight), there is a difference of over five gigabytes between F: and L:. Some of this could be attributed to differences in fragmentation between the two drives... but not 5GB worth. The drive level stats don't tell how many folders/files there are. Pity...

At the Root level (yellow highlight), where everything in Root is highlighted then right-clicked for Properties, there is a 3.6GB difference between F: and L:. Also, F: shows 16 folders and 92 files more than L:, no doubt accounting for the 3.6GB difference. But what/where are those files? I have Windows Explorer configured to show hidden and system files, and there are none showing for either drive.

I realize I should just close my eyes and be thankful that my backups are done, but these kind of discrepancies upset me.

tanstaafl.