Time Machine disk not mounting after sleep

Question

Greetings,
I am having a problem with the external USB disk (500GB Iomega) that I have set up for Time Machine not remounting after my iMac wakes back up. Nothing I have tried, short of rebooting, seems to cause the Mac to notice the drive. I have tried turning the drive off and back on, but that didn't work, and neither did unplugging and re-plugging the USB cable. (I suppose obviously) Time Machine won't do any backups and complains that "The storage location for Time Machine backups can't be found." Time Machine Set Up says "Next Backup: When Disk is Connected." If I reboot, the disk will show up and Time Machine will commence backups, but then, after the machine sleeps, I have the same problem again.
When I first plugged the drive in last night the computer immediately recognized it, mounted it, and asked me if I wanted to use it for Time Machine. I didn't have to do anything. I then successfully started Time Machine and it did its initial and several hourly backups as expected. Then the machine went to sleep and the disk never came back (short of a reboot).
The computer is a brand new 24-inch, 2.8Ghz, iMac with Leopard installed from the included DVD immediately after opening the box - I did nothing before installing Leopard.
This is my first Mac (I am a Unix refugee) so I may very well be doing something entirely stupid, but surely external disks should still be mounted (or automount) after the computer returns from sleep. What am I doing wrong? I also don't see any way to force Leopard to mount the drive, but I probably just don't know where to look.
To be completely clear... the drive is plugged directly into the iMac on USB, no external hub. There is no networking involved with this disk. I didn't make any kind of settings to the disk (either to the disk itself- there aren't any, or on the iMac when I plugged the disk in). The only thing I did was answer "Yes" when Time Machine popped up a window asking if I wanted to use the new disk for backups. Last time the disk was mountet (before the computer went to sleep again) I ran the Disk Utility and it said the drive was fine.
Thanks,
Mark
P.S. I'm sorry if this has been discussed elsewhere but I couldn't find it. Like I say, I'm new to the Mac and to these forums, so please forgive me if this post is redundant.

Answer 1

Greetings,
intelligenceresigned wrote:
Ok, I went into console, and forced my iMac to sleep to see what the console would show was actually happening. I am not a very computer savvy person, but this is what the console said:
Nov 8 21:50:27 steve-freunds-computer kernel[0]: USBF: 48332.754 AppleUSBEHCI[0x52ab000]::Found a transaction past the completion deadline on bus 0xfa, timing out! (Addr: 3, EP: 2)
I believe this may be related to the problem. The AppleUSBEHCI appears to identify the offending driver/controller as the EHCI controller (Enhanced Host Controller Interface), or the controller that handles usb 2.0 High Speed (usually usb 1.1 and 2.0 Full Speed are handled by something that would be called a UHCI or Universal Host Controller Interface) USB High Speed is the fastest of the three usb speeds and although the interface is compatable with the slower speeds, works rather differently than the other two. Beyond that I'll have to look into what this message means (I'm brand new to the Mac - I've only had this one a couple of weeks).
*Could others that are seeing this problem please post how many usb ports on the computer, not total devices connected to hubs or anything, but actual, physical ports on the computer that they are using?* Experimenting a little, on mine at least, I have not had the problem discussed in this thread when only two (out of the three available) of the physical USB ports on the Mac are used. Again on mine at least, it also doesn't seem to matter what, with the exception of external hubs, is plugged into the ports. Replacing the external drive with a flash drive or iPod Touch produces the same results, so it doesn't appear to have anything to do with the Iomega drive that I started seeing the problem with - it may be that that was just the third thing I plugged in (or not - I realize that I am a sample of one).
It also seems to be that things connected to an external hub continue to work after the other two ports have failed. This is probably why most keyboards (mercifully) keep working - they are usually hubs (Apple's external ones are). I can't guarantee this however because I haven't really tested it - just observed it so far to be the case for me so far. Hubs do work differently than ordinary usb "functions" as the usb spec calls them.
Lastly...
If you have Xcode installed (assuming you have it installed in the default /Developer location) there is a tool in /Developer/Applications/Utilities called "USB Prober" that can provide some useful USB information.
In my case, once a device stops working I see the status of the non-functioning devices reported as:
High Speed device @ 2 (0xFA200000): ............................................. External HD (did not respond to inquiry - 0xe00002ed, might be Suspended)
High Speed device @ 3 (0xFA400000): ............................................. HP Color LaserJet 2605dn (did not respond to inquiry - 0xe0004051, might be Suspended)
And indeed the usb ports in question do appear to be behaving as if the host (the Mac) has them suspended - but I can't be entirely sure. I will try to look into this some more later if I can.
Thanks,
Mark
P.S. To save questions: I've tried all the easy stuff: Switched cables, swapped out the hub I have on one of the ports, tried different devices in the ports (so far an HP printer, Iomega external disk, iPod Touch, and Sony usb flash drive). Nothing resolved the issue. My keyboard and mouse are connected to a 2.0 High Speed hub. I've tried using another hub, but it didn't make any difference.