Error 36 and External Drive File Copy Problem & USB Connections

Question

In attempting to copy a folder with some 200G+ of files from my iMAC, with OSX 10.6.7, to an external portable WD 1Tb HD, newly formatted to HFS+ (journaled), and connected to the iMAC via a USB cable to the USB port on the iMAC keyboard, I kept getting an error message that Finder could not complete the operation as some data couild not be read or written and transfered, and gave the "Error Code -36". After some searching ont he internet for this error code I came across a host forums discussiong the error code BUT all referred to it being the result of MAC OS hidden "dot-underscore" companioned files being created when the MAC OS X file system copies or moves files to a FAT16 or FAT32 volume. This was not the situaion in my case a both drives were OS X formatted HFS+. Eventually I came across a very vague reference to the error also occuring when the cable connection with the external HD was not solid. I reconnected my external HD and attempted the file transfer again - with the same result. Eventually I decided to plug the external HD into a USB pot on the back of the iMA itself, rather than the keyboard set. Sure enough the error issue disappeared - the transfer successfully completed.
So my question relates to the "usb connection" challenge with iMAC. the iMAC has only 4 USB ports on the back directly. I did have two desktop external HDs plugged into 2 of these USB ports at the back of the iMAC, as well as a WACOM pad device into the 3rd, and an EPSON 3880 printer into the 4th, and so was forced to employ the ports ont he keyboard for portable HD. So - what's the answer in a situation where the 4 are insufficient and it would appear that the keyboard ports seemed to be unpowered?? Any suggestions?

Answer 1

It's actually a Time Machine backup drive which is formatted in Mac OS Extended (Journaled). I wish I'd copied the exact error message.
I believe it was something to the effect of "Error 36: The file could not be copied because some of the date could be be read/written" or something along those lines. Next time it comes up I'll copy it. I have Drive Genius running with DrivePulse, but it doesn't ever seem to start.
My biggest concern is that this is a sign that the drive is failing. When backing up, it also slows, or stops midway through and just hangs there. Though I haven't done a lot of extensive testing on that because if the drive is failing, I don't want to speed that process up any more.
To add to the complication, there is a second external drive which Time Machine is also backing up for me. There is one particular file, the Virtual Machine file, I was trying to get off the other external drive and it produced the same problem. That's when I went into Time Machine to try and retrieve the file that way and it did the same thing. The other external drive is making some sounds, but it doesn't sound like a distinct clicking, more like a more pronounced version of the normal constipated hard-drive sound. The Time Machine drive, isn't making any obviously strange sounds at all.
So, I can't tell whether the drives are failing or if it could actually be that particular file itself causing some strange problems.