# Any hard drive limit on an iMac G3?



## Sunnz (Jan 30, 2007)

Got this one: http://en.wikipedia.org/wiki/Image:Steve_Jobs_with_iMac.jpg

But it is the (newer?) one with slot loading.

I am able to remove its hard drive.

Looks like an ordinary PATA to me... now wondering, if there are any hardware limit on how big (capacity) of hard drives this G3 will support?

I am planning to install some sort of BSD on to it, wanted to set up a file server.


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## Giaguara (Jan 30, 2007)

Here are some of the limits explained, and how to break those limits : http://lowendmac.com/macdan/05/1024.html


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## Sunnz (Jan 30, 2007)

So is it a hardware limit, or software? It is said that there is a driver to get around this... but if I use something other than OSX, would I need it?


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## Lt Major Burns (Jan 30, 2007)

it's a hardware thing, and you typically need a PCI slot to upgrade to it.


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## wraith (Jan 30, 2007)

I have an old iMac and ran into the hard drive sizing issue. Basically, I created 2 partitions, 1 for the OS, and 1 for Home Directories. (It broke the HD into small enough piecies for the hardware to use it.)


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## Sunnz (Jan 30, 2007)

Oh, so say if you have a 300 GiB HDD, you could do something like 100GiB for /, 100 for /usr and 100 for /home and etc. and it will work?


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## DeltaMac (Jan 30, 2007)

No, that's wrong. You're limited to devices (not partitions) of less than 128GB


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## Texas Mac Man (Jan 31, 2007)

Look at these links.

What Macs natively support large IDE drives? (over 128GB formatted)
http://forums.xlr8yourmac.com/actio...onse=answer.faq.lasso&-recordID=34188&-search

How Big a Hard Drive Can I Put in My iMac, eMac, or Power Mac?
http://lowendmac.com/macdan/05/1024.html

Using 128 GB or Larger ATA Hard Drives
http://docs.info.apple.com/article.html?artnum=86178

Cheers, Tom


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## Sunnz (Feb 2, 2007)

Thanks guys.

On OpenBSD PPC mailing list, I've found out that the limitation is limited by the OpenFirmware used in iMac G3, so when I insert the OSX CD it can only use 128 GiB.

I am installing OpenBSD now which does not rely on OpenFirmware and well, it is now formatting the whole 320GiB HDD, seems like it actually does work now!!!

So, it is not exactly a hardware thing,  just a limitation in the OpenFirmware.


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## DeltaMac (Feb 2, 2007)

Well, sure, good luck on that.
You would be wrong, but good luck, anyway.

The limitation is provided by the drive controller chip on the logic board, and would not be controlled by Open Firmware, nor something you can bypass completely by simply installing BSD, and is truly a hardware limit.
This will make itself known the first time you copy files to fill past that 128GB limit.


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## Sunnz (Feb 2, 2007)

So it is _really_ a hardware issue??? 

It is all formatted now and installing the system files... so you are saying I shall fill it up pass 130GiB and see if it still works?


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## DeltaMac (Feb 2, 2007)

Try it if you like...


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## Sunnz (Feb 2, 2007)

I don't have much of a choice anyway...

What if I put it in a external enclosure and connect to it using USB, would there be any limit then? (Not worry about booting up using USB, I can always just use the original HDD for boot up then mount the new external disk.)


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## DeltaMac (Feb 2, 2007)

Sure, that's a solution. External drive cases sold within the last 2 or 3 years should support large hard drives.


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## Sunnz (Feb 11, 2007)

Yea I got a few spare ex-cases lying around.

Seems like it isn't needed though, the internal hard disk has been filled pass 130 GiB, today. (See attachment.)

Convinced yet? What else shall I check?

By the way, this is one of those 'newer' G3, not the Blueberry, but I believe it is the Indigo, with 500 mhz clock speed... maybe it had a newer board after all and therefore does not suffer the 128GiB problems of earlier G3 models?


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## DeltaMac (Feb 12, 2007)

Sunnz said:


> Convinced yet? What else shall I check?
> 
> By the way, this is one of those 'newer' G3, not the Blueberry, but I believe it is the Indigo, with 500 mhz clock speed... maybe it had a newer board after all and therefore does not suffer the 128GiB problems of earlier G3 models?



Not convinced - no G3 has support for larger drives.
Why does your df command not show all your partitions? I run the same command, and mine shows 8, including automounts. (also a 500MHz iMac)


> c-71-200-34-176:~ dad$ df -k; df -h
> Filesystem              1K-blocks     Used    Avail Capacity  Mounted on
> /dev/disk0s10            62904000 23167340 39480660    37%    /
> devfs                         100      100        0   100%    /dev
> ...


A partition over 128GiB, on a logic board that doesn't support it, is like waiting for the bomb timer to stop ticking. It will happen - you won't be able to ignore the file corruption. I suspect you haven't rebooted that iMac yet? BTW, there's no need to have a boot partition of less than 8GB, that's only needed on the oldest, slot-loading, iMacs.


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## andychrist (Feb 12, 2007)

You mean the oldest,_ tray_-loading iMacs.


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## Sunnz (Feb 12, 2007)

DeltaMac said:


> Not convinced - no G3 has support for larger drives.
> Why does your df command not show all your partitions? I run the same command, and mine shows 8, including automounts. (also a 500MHz iMac)


Different OSes...


> A partition over 128GiB, on a logic board that doesn't support it, is like waiting for the bomb timer to stop ticking. It will happen - you won't be able to ignore the file corruption. I suspect you haven't rebooted that iMac yet?


No I haven't... so I should reboot and expect there is a file corruption?


> BTW, there's no need to have a boot partition of less than 8GB, that's only needed on the oldest, slot-loading, iMacs.


Ok but I haven't defined a separate, /boot partition... unless I misunderstood something...


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## DeltaMac (Feb 12, 2007)

Sunnz said:


> No I haven't... so I should reboot and expect there is a file corruption?



I hope you don't get file corruption, but you won't be able to control that, now that you have 'stepped over' beyond 128GiB - that may be one result when using a drive controller beyond its design capabilities. You just won't know when your directory will 'blow up' for you.
Good Luck!


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## eric2006 (Feb 12, 2007)

It may work, it may not - just don't save any critical files there.


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## Sunnz (Feb 12, 2007)

Well it does work as it is running _now_...

I'll report back here if anything funny happens, but it seems to be fine now.


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## Sunnz (Feb 13, 2007)

Hey DeltaMac may I ask what is your expertise? You seem to know a lot about hardwares, do you know which logic board is used in the G3 that does not support large hard drives?

Do you know why there is a limit? It is kinda funny how a partition over the limit could actually be created, I mean, how could this happen? Usually when the hardware doesn't do something, it just simply can't.

I will probably just pop that disk into an external case... so I am doing this now because I want to see how things worked and where the if the limit is real or what not.


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## DeltaMac (Feb 13, 2007)

The limit was there, because large hard drives did not exist at that time. The largest capacity generally available in 1999-2000 was 60GB, maybe 80GB.

The external case will be a good choice - your directory will eventually fail - you can bet on it, you just won't know exactly when the trouble will start.

You can actually format the drive in an external case, and then transplant into your G3, but that simply gets you a large partition. The problem will remain - it will fail sooner or later, as long as the larger partition remains.
Here's a nice article concerning that limit
http://www.48bitlba.com/overview.htm


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## Sunnz (Feb 13, 2007)

So the G3 has only got 28-bit addressing for hard disks - so 2^28 of 512-byte sectors are available, which can only handle 137GB/128GiB at best...


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## DeltaMac (Feb 13, 2007)

Now you've got it! Of course, it's not strictly the G3 processor, but the IDE drive chip on the logic board, and the ATA-4 drive protocols (or older). ATA-5 (mostly), and ATA-6 support the 48-bit LBA. This was not provided until well after the G4 was introduced. The PowerMac G4s can be updated simply by popping in a newer IDE drive controller card. An iMac, unfortunately, cannot have that hardware updated.


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## Sunnz (Feb 14, 2007)

Well I understand it a bit more... but still very puzzled. I got have over 200GiB on data on the disk and I could access all of them (I actually read through text files, open PDF, and playing movies.) - I mean, this is impossible, right?

If, the logic board, reported as "Apple Pangea Macio" in dmesg, cannot get over the 128GiB boundary, it shouldn't be able to write to it...

However, there wer "soft errors" when the data was being copied over:
	
	



```
wdc0:0:0: intr with DRQ (st=0x58<DRDY,DSC,DRQ>)
wd0h: device timeout writing fsbn 470922496 of 470922496-470922623 (wd0 bn 539606608; cn 535324 tn 0 sn 16), retrying
wd0: soft error (corrected)
wdc0:0:0: intr with DRQ (st=0x58<DRDY,DSC,DRQ>)
wd0h: device timeout writing fsbn 424058080 of 424058080-424058207 (wd0 bn 492742192; cn 488831 tn 8 sn 40), retrying
wd0: soft error (corrected)
```
It is said that it had to make multiple attempts to write the sector to disk, but that eventually it was able to do so. Hence a "soft" failure. Sounds familiar?? Did it actually find a way to get around the boundary or what?

Hmmm I don't know... I googled "Apple Pangea Macio" but can't find anything... anyone know if "Apple Pangea Macio" is the logic board???


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