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PostPosted: Tue Dec 20, 2016 7:18 pm 
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I've purchased a "lightly" used late 2009 iMac ( A1312, EMC 2306 ) thinking that if my attempts
to revive my other iMac fails I have a backup.

I have a hd already installed with Lion that I was using to boot into to sync my iDevices on the other iMac
till the enclosure went south, so I figured since the 2009 iMac shipped with Snow Leopard ( 10.6.1 )
it should be an easy peasy swap, but no joy, the iMac boots fine but I get the question mark folder.
The only thing that I did not reconnect was the temp sensor since my Lion drive did not have
the same socket on the drive that the original drive had, I figured that all I would get is roaring fans.

Is there a something I missed ?


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PostPosted: Tue Dec 20, 2016 11:04 pm 
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I'd say the 10.6 OS has lost reference to itself as the startup disk, now a different disk is being used. Does the Lion installation also have a recovery partition on it that you can boot into and from there I think you can reselect it as the startup drive.

Or you could await wiser counsel from Anon or MB.


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PostPosted: Wed Dec 21, 2016 7:26 am 
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Does alt key at boot up show boot choices?


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PostPosted: Wed Dec 21, 2016 12:54 pm 
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I remembered that the hd that had Lion installed was in a newish Ministack classic enclosure
that went belly up ( yay Newer Tech, NOT ! ) and it probably scrambled something on the drive,
just now I booted up off DW and while the hardware part of DW saw the drive and tested it OK,
the Files section did not see a hd.

What has me wondering is how important the temp sensor cable is for the iMac to see the internal drive ?

Previously they were small boards that were double sticked to the hd case,
as an aside, anyone know how they work since all that's on the little board is a chip.
In a 2009 iMac they plug into the drive and from web info, uses the drives built in internal sensor.


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PostPosted: Wed Dec 21, 2016 1:45 pm 
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To see the internal drive? Not at all important. It just won't know what temperature the drive is, which is why the fans usually to ramp up.


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PostPosted: Wed Dec 21, 2016 4:41 pm 
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That's what I thought Monkeyboy, anyone care to surmise how a
2TB drive became a 250 GB fat32 drive without any human intervention ?


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PostPosted: Wed Dec 21, 2016 6:11 pm 
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It possible it was formatted strangely by the enclosure. I recently saw a 3TB WD drive that was MBR formatted by the case with a weird multi-partition structure that had a series of partitions in 250GB chunks. I ended up only being able to access the first one because of actions performed by the owner, but a raw drive scan ended up finding the rest. MBR can address a maximum of 2TB, so this is completely off-the-wall weird. I got the data back by having the guy run out and buy another same model WD drive and putting it inside that enclosure (he blew up the original case by plugging in the wrong power supply). The HD in that one was similarly formatted. Enclosures are free to format the drive inside however they want to format it, the data they present on the external interface doesn't have to match the internal.

If the enclosure failed it's possible it - or more likely the system connected through it - scrambled the data on the drive trying to make heads or tails out of the data on the drive through a circuit that was failing to work correctly. OS X will automatically fsck a drive if it has trouble mounting it... I believe it attempts to replay the filesystem journals (the last series of operations performed to the drive, basically) and if it totally can't use them to recover a working filesystem (think of it as walking forward through a list until you get to the end, seeing that its not going to work, then rolling back, seeing if its going to work, rolling back if it doesn't, etc.) it will then fsck as a last resort.

I tend to do a lot of data recovery and this isn't entirely unexpected when you're dealing with failing hardware. I always hope and pray that people in these situations have good backups because sometimes that's the only thing that saves you.

If you can't get the data back I would just put a fresh OS X installation on the drive and see if it works then. If it does, then it was just scrambled when the case failed. If it doesn't then you've got a mystery on your hands and will have to figure out where the problem is.


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PostPosted: Wed Dec 21, 2016 7:25 pm 
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Your experience with a gremlin formatted drive is interesting, I'll have to eat the data loss which really amounts
to some work pictures and reformat the drive and see if the Ministack enclosure or the drive is the cause.
I tend to lean towards the enclosure being the cause, this would be 2 in a row with Newer Tech products.


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