Repeated error: 11 problems while trying to backup to time machine

Question

A few months ago I purchased a 750GB NESO external hard drive and have never been able to back up using time machine on it. I can manually back up files no problem, but I have yet to get time machine to finish a complete backup, despite trying every fix I could find on the internet.
This includes reformatting the external, making sure there is a separate partition for the Time machine backup, making sure that partition is formatted as Mac OS extended (journaled) and GUID.
Every time I try to back up I get the same error message: "An error occurred while copying files to the backup volume". This happens at various time during the backup process. Sometimes after a few MBs, sometimes after 1.5 Gigs have been backed up.
This is what I get from the system log every time-
*Feb 3 18:34:59 Computername com.apple.backupd[1228]: Copied 137 files (1.2 GB) from volume Macintosh HD.*
*Feb 3 18:34:59 Computername com.apple.backupd[1228]: Copy stage failed with error:11*
*Feb 3 18:35:04 Computername com.apple.backupd[1228]: Backup failed with error: 11*
*Feb 3 18:35:05 Computername UserNotificationCenter[1282]: Error loading /Library/QuickTime/DivX Decoder.component/Contents/MacOS/DivX Decoder: dlopen(/Library/QuickTime/DivX Decoder.component/Contents/MacOS/DivX Decoder, 262): no suitable image found. Did find:\n /Library/QuickTime/DivX Decoder.component/Contents/MacOS/DivX Decoder: no matching architecture in universal wrapper*
*Feb 3 18:35:54: --- last message repeated 37 times ---*
I have tried excluding the divx decoder.component file I located in the Quicktime folder, I have excluded the whole Divx application, I have even excluded the entire Quicktime folder. I also reseted the time machine setup including erasing the existing "/Time Machine Backups/Backups.backupdb/nameOfComputer/date.inProgress" file as advised in the troubleshooting guide in this forum after excluding each. Still the same error every time.
After having tried all suggested solutions including those listed in the troubeshooting guide here I am truly baffled as to what the problem is. Please advise.

Answer 1

brocktoon4 wrote:
Any idea how this is possible? Did the smaller partition isolate the defect? Thank you again for all your suggestions and help. I am relieved to finally get time machine working. If you can shed some light on this little mystery as well I would be grateful.
I don't have a lot of expertise there, but yes, if there's a bad spot on the disk, in the area where TM was trying to put new backups, that could do it.
Partitions aren't like folders, where their data may be scattered; each one is on a +*physically separate+* part of the disk.
Usually, if there's a bad spot, it will be discovered when writing to it; any time you do a write, it's automatically read back and compared. If there's a problem, it's retried a certain number of times, and if it still fails, the sector is marked "damaged" so it won't be re-used, and a different sector used.
I would strongly* recommend that you not trust your backups to a drive that's had such trouble, especially if they're your only backups.
I learned many years ago (the hard way, of course ), not to trust my backups to a single app or piece of hardware. No app is perfect; neither is any hardware.
You might want to keep a secondary backup, such as a "bootable clone" of your system, on a separate external disk. This is commonly done with CarbonCopyCloner (which I use in addition to full Time Machine backups) or SuperDuper. There are variations, but typically a clone is an exact copy of your system, with none of the previous copies of things you've deleted or changed, like Time Machine keeps. Unlike Time Machine, you can boot and run your Mac normally (but a bit slower) from them.
This gives you the advantages of both types of backup, and protects you from a problem with one of them (external drives fail, too). Some folks do the "clone" to a portable external HD, and take it to their safe deposit box, workplace, relative's house, or other secure location periodically. Others have a pair that they swap weekly or so. Thus they're also protected against fire, flood, theft, direct lightning strike on their power lines, etc.
CCC is donationware, so you can use it free for a while. If you decide to keep it, send them some $$ so they can keep it up to date. SD has a free version, but to do updates (rather than a full replacement) or automatic scheduling, you need the paid version (about $30).
Either is available via Google, VersionTracker.com, or MacUpdate.com.