Possible Daisy Chaining Issue with G-Tech Ext HD

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16 points

Possible Daisy Chaining Issue with G-Tech Ext HD

I've had ongoing issues that I think might be related to daisy chaining G-Drive external HD from G-Tech. There's a long and sordid history here but first the pertinent details:

The symptom: applications stop responding and I have to reboot and the finder can also stop responding and I have to reboot. I've noticed that when this happens Time Machine is trying to "calculate" (I assume the amount of new data it needs to back up) but it seems to get stuck and never goes beyond the calculating mode.

History: Since buying my first iMac in March 2009 I've had problems with corrupting data and the symptom above. I bought two G-Drives to daisy chain with that new iMac. Soon, but not immediately, data started to get corrupted. Got another iMac and this time kept only one G-Drive attached. All seemed fine for about a year but then I started to get the symptom above last July. All tests I conducted on the OS and hardware were green. Took it into Apple Store and they saw a bad heat sensor. They replaced the mother board and computer then started turning off by itself. Apple replace computer in August.

So now I've got a new iMac. At first, I didn't connect any external HDs to the computer. No problems. Then I bought a Seagate 3TB drive and hooked it up. No problems. So after a month of flawless computing, last week I decided to hook up one of the G-Drives to the Seagate via Firewire 800 daisy chain. No problems for a few days but then the other day the symptom above started to happen again. Apps started to stall.

This morning, my finder went missing. On reboot (keeping the externals connected) I didn't even get the Apple logo on the white screen. When I unplugged the external HDs the computer booted fine.

So, this is where I am. I am really starting to suspect the G-Drive as a longstanding culprit (I've read that some have had problems with daisy chaining G-Tech drives but not the exact symptoms I've had). But I can't figure out why. It's not a clear issue (I hate these "soft" issues -they drive me crazy).

Next steps: first, I will keep all externals off for a few days to see if that helps. Then I will connect just the Seagate and see what happens then.

I'm concerned that the daisy chaining may have hurt my computer hardware. Thoughts? Could there possibly be a overheating issue. I tend to keep my computer on for days. What tests/maintenance should I perform?

Thanks.

27" iMac, Mac OS X (10.6.3)

Posted on Nov 9, 2010 6:44 AM

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Answer 1

den.thed

Level 9

77,044 points

Nov 9, 2010 9:00 AM in response to outtacontext

Hello outtacontext

At first read it sounds like maybe a shorting or intermittent problem with a FireWire cable or the Drives A/C power supply, until you get to the part where it works fine for a couple of days and then goes on the fritz again?

At this point I still suspect a bad cable or power supply, but now have to ask.
1. Are you properly ejecting the drives before disconnecting or powering them off?
2. Is the Time Machine drive dedicated to only that, or are you also using it for other stuff?
3. Are running apps from or using any other backup software on the same drive as Time Machine?
4. When you first setup the drives, did you reset the Partition Map Scheme to *GUID Partition Table* and the Format *Mac OS Extended?*

Dennis

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Answer 2

outtacontext Author

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16 points

Nov 9, 2010 9:09 AM in response to den.thed

Thanks for the response den.thed. Here are my answers to your questions:

1. Yes, I eject properly (but I don't often eject at all)
2. Time Machine is on its own partition on the Seagate drive.
3. I am not running apps from or using any backup software on the same drive as TM.
4. I'm not sure but I suspect I did just that (I am not near my home computer at the moment.

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Answer 3

den.thed

Level 9

77,044 points

Nov 9, 2010 10:05 AM in response to outtacontext

OK good, hope you understand that I had to ask!

It might be the second partition on the Time Machine drive causing a problem, is that partition just for storage or are you working in it and backing up to Time Machine at the same time?

If so, then both partitions may bog-down and could become corrupt.

If not and I read correctly, then it seems like one of the G-Drive is dragging down and causing a problem for the whole FireWire chain? If so then I'm back to the bad cable or power supply theory and would try, both a different FireWire cable and A/C power supply on that Drive. Another thought is to put the drive in question last on the chain in case there is a problem with the thru put of the enclosure. Lastly, then if it was still causing a problem I would push on G-Tech to service or replace it under warranty.

http://g-technology.com/products/g-drive.cfm

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Answer 4

outtacontext Author

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16 points

Nov 9, 2010 2:13 PM in response to den.thed

The Time Machine is all by itself in its own partition. And TM is on the Seagate, not the G-Tech HD. There is nothing in either of the other two Seagate partitions at the moment. (The drive is new and I haven't added anything yet.)

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Answer 5

den.thed

Level 9

77,044 points

Nov 9, 2010 2:39 PM in response to outtacontext

Oh OK, somehow I got the impression that you were using 1 of the G-Techs for Time Machine before you got the Seagate?

At this point I have no idea if 1 of the G-Drives is the problem, or if the thru put power demand on the Seagate is the problem.

However I would think that the G-Drives have better enclosures and would try a different chain configuration, example: the G-Drive(s) first and put the Seagate at the end of the chain.

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Answer 6

outtacontext Author

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16 points

Nov 9, 2010 7:11 PM in response to den.thed

Before I got the Seagate I was using one of the G-Techs as my Time Machine. But when I got the Seagate, I made one of the partitions the TM.

I was having no problems until I daisy chained the G-Tech to the Seagate. I would think that the problem may still reside with either the FW daisy chain cable or the G-Tech power supply.

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Answer 7

outtacontext Author

Level 1

16 points

Nov 10, 2010 4:23 AM in response to den.thed

Ran disk utility on the internal HD. Only thing I got was a nissing thread record and a missing directory record with resulting invalid volume file counts. DU fixed that. I ran DU on my Seagate with its three partitions. All checked out okay (one of the partitions has Time Machine on it). Then I ran the Hardware Apple Test and all checked out.

I believe my problems probably stem from the G-Tech (it's an educated guess based on the fact that I had no problem before I hooked the drive up last week), its FW800 cable, or the power unit. And I am going to keep the drive disconnected. It's simply not worth it to me if it gives me problems. And I don't want to tax my computer's power supply or other hardware.

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Answer 8

den.thed

Level 9

77,044 points

Nov 10, 2010 6:02 AM in response to outtacontext

Sounds like a plan to me, I don't blame you for being leery given the past problems. Personally I would copy anything important on the G-Tech over to say the third partition on the Seagate so that at least the data is saved and accessible in the future.

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Answer 9

outtacontext Author

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16 points

Nov 10, 2010 6:05 AM in response to den.thed

The only thing on the G-Tech is my SuperDuper backup. I've also got Time Machine and off-site Mozy so I'm not really worried. I could put SuperDuper on one of the partitions. And I may do that. The only problem with that is that would mean I'd have two backups on the same piece of hardware. If something should ever happen to the Seagate, that could be a problem. I may just buy another drive (any suggestions?) G-Tech is supposed to be good (and maybe it is) but, as I said, I'm a bit nervous.

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Answer 10

den.thed

Level 9

77,044 points

Nov 10, 2010 6:36 AM in response to outtacontext

Agreed, it's not worth copying an old backup over. Perhaps at this point it might be best to just update the SuperDuper Backup on the G-Tech and put it aside for safe keeping.

Of corse having two reliable drives one for Time Machine and one for SuperDuper is the best approach.

However I see nothing wrong with having a weekly SuperDuper Clone on one of the other partitions, in fact if the drive has room to spare it's not a bad idea at all. That way if you run into Internal HD issues you can always boot and run from it for troubleshooting and repairing your Macintosh HD instead of having to spend time Restoring from Time Machine.

Personally in my backup strategy, I have several External HD's and put far more faith in my alternating weekly bootable clones than I ever will in Time Machine.

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Answer 11

outtacontext Author

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16 points

Nov 10, 2010 6:41 AM in response to den.thed

Since I have nothing on either of the two other partitions on the Seagate, I think doing a SuperDuper on one of the partitions and leaving the third for data is a good idea. Thx.

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Answer 12

den.thed

Level 9

77,044 points

Nov 10, 2010 6:47 AM in response to outtacontext

Your welcome!

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