Background

A month or two ago I purchased a new 250Gb drive to put into my Macintosh. I remember that I wasn't paying attention when I installed it because, with a Mac, things like that generally "just work". I launched the Disk Utility application to partition the drive into two different chunks, clicked a couple of buttons, and pressed 'Partition'. I waited and waited, did other tasks, and waited some more. Compared to other occasions, Disk Utility seemed to be taking its sweet time so I stopped the process (actually a force-quit). I re-launched Disk Utility to try again and this time I was paying attention. To my dismay, I saw that the computer only recognized a 128Gb hard drive. I thought that giving Disk Utility a force-quit had messed up the drive! I tried a couple of different tricks but I wasn't able to get the computer to recognize the whole thing. I was short on time so went ahead and used the drive as 128Gb because I needed to make some long overdue backups. I told myself that I would work it out later.

Well 'later' arrived recently and my plan was to order another 250Gb drive (because they're inexpensive), install it, and move my data over. Once that was done I would tend to the misbehaving drive.

When I received the hard drive I put it in my FireVue, an external firewire enclosure I bought many moons ago from a company called Granite Digital. I tried this first because putting a bare drive into a FireVue tray is easy and I didn't have to shut down my computer. I turned on the case expecting a brand new 250Gb drive, but was unpleasantly surprised when it showed up as 128Gb! Damn!

Still clueless, I needed to simplify the equation and that meant taking the drive out of the FireVue tray and installing it inside of my Macintosh directly on the IDE chain. I did that and tried all sorts of partition/formatting combinations using Disk Utility, even zero-ing the drive, but nothing worked to get the whole 250Gb. Actually, most of the time Disk Utility would show the spinning beach ball and, much later, would stop processing and display an 'input/output' error.

Being too coincidental to have the same problem with two different drives, I figured that I didn't hose my first drive (whew!), but in fact had another problem to tackle. So I started off to research why my Macintosh was only showing half of the drive's size.

Problem

The punch-line to this story is that all computers and hard drive hardware having a controller based on a communication protocol known as ATA-5 can only address up to 128Gb of data (or 137Gb, depending on if you say toh-may-toh or toh-mah-toh). So if you use a large hard drive the hardware is only going to recognize the first 128Gb.

A newer drive protocol called ATA-6 has been out for a few years and current hardware based on this version can address as much as 2 terabytes of information! That's 2,000 gigabytes per hard drive! Because this is a newer protocol there is a lot of computer hardware out there which has this 128Gb issue, including my beloved FireVue which I purchased around 2001.

From my research I found out that Macintoshes manufactured before June 2002 use the older ATA-5 protocol. Looking at Apple's web page on PowerMac specifications, I can see that Harold, my 'newest' computer, was first introduced in September 1999 and was phased out 1 year later; this was well before the June 2002 cutoff. The first PowerMacs to use the ATA-6 protocol, thus immune to the 128Gb limit, were introduced in August 2002 and can be distinguished by their mirrored drive doors.

Now that I knew the problem, it was time to find solutions.

Solutions

For Harold, I found a company called Speed Tools which sells hard drive utilties for the Macintosh. The Speed Tools product ATA-6 which costs $25 will allow your Macintosh to use larger hard drives.

After I purchased the software, a quick installation and a reboot I could instantly see the larger drive on my computer and Disk Utility didn't have any more issues formating or partitioning the drive.

Another solution I came across was to use a third-party hard drive controller which would be installed inside of a computer. These cards have their own IDE connector used to attach internal hard drives. Unlike the software from Speed Tools, these cards can only be used with PowerMacs because they require a PCI slot for installation.

Unfortunately, I had a little less luck finding a workable solution for the FireVue case. I actually had checked Granite Digital's support site first for information and happily found a firmware update for their enclosures. After I installed it, my computer could see all 250Gb, but Disk Utility still couldn't format or partition the hard drive. Also, as I read through their FAQs, I found a question covering this issue and it warned of the possibility of data corruption. This concerned me.

I called Granite Digital to get more clarification from someone in technical support. As it turns out, the older enclosures based on ATA-5 can see hard drives larger than 128Gb using their firmware update. They can even work with a special Maxtor 160Gb drive without the firmware update. However, Granite Digital doesn't recommend using larger drives with their enclosures manufactured before December 2002. It'll work for awhile, but you should expect data corruption as time goes on.

So, I'm going to move my smaller drives to the two swappable trays that I have for my firewire enclosure, put my two large drives inside of my PowerMac and rely on the ATA-6 software to do it's thing. In the future I'll be upgrading to a dual-bay, FireVue firewire enclosure from Granite Digital.

Summary

If you have a PowerMac manufactured before June 2002, you can either:

• purchase hard drives which are smaller than 128Gb
• install the Speed Tools ATA-6 software
• install a third-party hard drive controller
• buy newer firewire/USB external hard drive enclosures

Resources

Solutions

• Granite Digital FireVue dual-bay enclosure (ATA-6)
• Speed Tools ATA-6
• Sonnet Tech ATA-6 IDE controller

Support Sites

• Granite Digital Support
• Apple Support: Using 128 GB or Larger ATA Hard Drives

Forum discussions

• XLR8YourMac: Large drive support
• Apple Forum: 300 Gig drive shows as 128 Gig