Add Storage when your Disk is Full

Ever run into this message on your Mac ?
The Problem !
I did! And I started deleting files right away. But there weren't many I could think of, so after a few minutes, and 5 MB more disk space, I sat back and started to think. A message from the 90's asked me to delete files?! Disk space is cheap these days and deleting photos, songs or movie clips from the last vacation? No way.

More disk space seemed to be the better answer. An external hard drive. Then I realized my backup could become a lot more complicated. And which files and folders should I move to the external drive. iPhoto?, iTunes? Managing critical content on multiple disks? Who wants to do that? We are busy with creating more content.

Next thought - a bigger startup disk! That's it. That solves it. How though? I had two options:

   1. - Backup the old system disk (got that one!).
      - Buy a new hard drive with three times the capacity of the old one.
      - Install it.
      - Reload the system OS and restore the backup.
      OR,
   2. - Buy a new Mac with a bigger disk.
      - Mmmh - not so fast!
      - My "old" Mac had just had its 2nd birthday!

I ordered a bigger disk.
Five days later I finished the job and enjoyed the feeling that I was one of the few who could do this type of work without asking anybody for help. Felt great - for about a minute, because a thought had popped into my head.
A friend of mine had bought an iMac just about a year ago and the entire family was shooting photos and video left and right. He doesn't have two left hands, but he's just not that into computers. What will he do when he's running out of space? Call me?

That's when it hit me. What an antiquated system are we having to deal with here.

    * Why is adding disk storage not as easy as adding RAM ?

If that would be possible, how much different would adding storage be compared to the steps I had just completed? Let's see:

The Best Way
That ominous morning I would see a slightly different message popping up on the screen:  First the same alarming thought, then relief. Get more storage, sure. I click the OK button and my browser opens a screen in the Apple Store that shows me a list of disk modules with different capacities. I select a 180 GB module, proceed to the checkout and finish the transaction. Three days later I receive the part in the mail and plan to add it to my iMac when I get home.

After dinner I check out the new storage module. Looks a little smaller than a 2.5" drive and about 1/2" thick. Here are the installation instructions:

   1. Open the back panel on the left side of your iMac with the small Philips screwdriver.
   2. Starting at the bottom locate the next open slot above the existing storage module(s).
   3. Insert the new module (arrow up).
   4. Close the back panel.
   5. Turn on your iMac.

When I plug in the new module I see that there are 2 more empty slots available. Nice. After closing the back panel I turn the Mac back on and after the desktop appears a window pops up telling me that it detected a new storage module and gives me choices:
1.- Do I want to add the new module to my existing startup disk, 2.- use it as an additional disk, or 3.- add it as a backup disk?
I select the first option and click the OK button.
After a few seconds another window tells me that my startup disk has a total space of 360 GB and 183.5 GB of free space. The Mac had just combined the space on the new disk and the space on the old disk! I check the desktop: still just shows one disk icon. I run the Disk Utility - still just one volume, but in the column next to it I can see the OK status of two disks.

Wouldn't that be a nice way of adding disk capacity to our iMacs? Just like adding RAM. And on top of it all, you can add two more drive modules and run a smart RAID concept making sure that your data is protected in case a module fails or is about to fail. And even if I would get that "Your Startup Disk is almost full" message again with all slots loaded - I would just replace the oldest and probably smallest module with a new and bigger one. Infinite storage !

If this concept sounds familiar to some of you, you are correct. In Mid 2007 the Drobo - an external USB hard drive array was introduced by DataRobotics. It is one of the best external storage solutions for the Home and Small Businesses - and it uses the same concept as I described above. It's an external drive, though.
The story above is all about the startup disk - and happened in early 2005.

So the Story goes on ...
I shared this how-to-easily-add-capacity story with quite a few people. The Apple contact to whom I talked to in early 2006 fully agreed with me. However - while I was about to talk how a disk controller chip could do all that, he started to explain the features of a new file system, called ZFS, that had been developed by Sun Microsystems.

So while we both had come to the same conclusion - ease of use for the user when adding storage - we accomplished it in quite different ways.Both approaches required quite a few hardware changes - very similar ones, though. However, somehow it seemed that only the ZFSapproach would have a real chance of proceeding.
So I thought.

Fast Forward to 2009
As we know now - ZFS is still elusive in the Mac OS - and two years ago my Apple contact moved on to work on enterprise-level storage ideas in another domain. The Mac's architecture moved to Intel processors and ConnectionLabs - the company I had founded in 2003 didn't go much further in 2006. Its prototypes and product concepts, however, all moved up into the real world.

Today Apple could implement this new storage concept by either using a Silicon Image chip for controlling multiple disk drives and aggregating their capacity, or do the aggregation of disk space and protection of data files with ZFS. Interesting enough - the SI chip would still be involved providing the physical connections to the disks.

Still, not a simple task but who says life is easy! It could be fun though. Working on something that has a good potential of disrupting the existing market.

    * It means that a re-design would not be limited to a slightly faster machine and a slimmer aluminium case.
    * It means that disk drives for these storage modules would need to get a bit smaller.
    * It would mean innovation - a new storage generation.
    * It means that the starting capacity of a new iMac could be at a "lean" 160 GB; not the 320 or 650 Gigs. Who really wants to have 300 GB spinning around empty for a year?
    * It means that the iMac would have to get slots for these [eSATA] connectors on its side so it can accommodate those storage modules which, btw. could even be solid-state drives. 128 GB are still a lot cheaper than 300 GB modules. Add the 300 GB one next year when you need it and it is costing a lot less. (see how it works in a laptop)
    * It could mean that solid-state-storage would probably be used in a lot more systems.
    * It means that only Apple could do this - since it's controlling both hardware and software.
    * It means PCs would be stuck with the "old stuff" for years longer.