Can I move my operating system to a different partition on the same drive?

Question

I thought I knew what I was doing when I partitioned my hard drive and installed the operating system and everything else. The other partitions are for documents, photos, etc. It worked well for quite a while but now I find there is not enough free space on my start-up partition (24GB) to be able to do new installations. I have cleared a 50 GB partition on the same drive to be the new home of my operating system. I tried copying all the files in the System partition to the new drive but "Startup Disk" doesn't recognize the copied version. How can I make this work without having to install everything all over again?

Answer 1

Too true. I have been partitioning my drives since the 80's when it was "illegal" and voided warranties as was opening the case on a Mac. Now the cases open right up and you drop and slide in new drives and memory. And it has saved my butt many many many times. You put your operating system on one partition, from what I have read it is best on the first partition of the first hard drive in the chain, Master, if you have more than one drive. I have four drives with now down to 8 partitions with the last two 10.4.x OS's that worked well and my last 10.5 for emergency use, all on one drive in separate partitions and boot to them all the time with no problems. I always keep my last install just in case intact and bootable. It's no different than what is done with BootCamp and running Windows. Then put all your data, files, non-Apple applications on another partition(s). That way when the OS hammers, and it will, all you have to recover is the OS and your data is safe. Thenall you really have to worry about is certain preferences and databases that have to be on the start up partition that won't work when aliased. I have found them, and they are few, and use Backup from the iDisk software library to back these files up to my iDisk nightly. And having the OS all by itself makes back ups so much easier and smaller. But you have to leave Apple applications on the OS partition in the Applications or Utilities folder or the Apple Updater will not see them.
Before iTunes and iPhoto would allow you to link to databases that are not on the start up partition, I was aliasing those files from other partitions. Then early 10.5 it didn't work as well, now when you hold the option key prior to starting up in iTunes and iPhoto you'll get a window to go find or create any of many databases to run off of. I have done this for years with Apple, Microsoft, Macromedia, Adobe and many other applications.
So far my largest OS has been 14.6GB after I installed GarageBand and it loaded a ton of instruments on to the OS partition. I have been through this before and found them and moved them off to another partition and aliased them back and GB works great. Otherwise, even in 10.5.x you can have relatively smaller partitions. And yes you want room to grow, if even just scratch disc space that some applications will not let you choose or go off the OS partition. So I hover around 25-30GB partitions and have never gotten close to getting more that 60% full, fulfilling the 10-15% free space axiom that seems to get larger with every update. I have read here that several people that had taken their machines to an Apple where they replaced drives saying that the techs partitioned the drives and said that the minimum for 10.5.x was 12GB. As the updates flow, that will vary probably up. Plus Apple has some bloated applications and a ton of things that you'll never need or use that take up room that are a pain to find, like unnecessary fonts. A little extra space is always good.
I use CarbonCopyCloner to make compressed back ups and bootable clones. The older versions would not copy files that would be easily rebuilt when you booted that OS, thus cleaning up the clone/back up by cleaning/omitting files that normally get damaged. Not sure if that is part of the latest versions. I think they copy everything. Another great thing is that Apple installers and Disk Utility and can use them to restore or migrate from. Because of CCC, I now have it down to 10-15 to restore a crashed or failing OS from parts. I have yet to loose anything, except time in having to deal with an OS that sometimes has a mind of its own.
As you play around as I did when I was waiting for an Apple Tech Rep, and reran the Combo Updater back over a wonky install, to find out if you could do that, it was done and worked great just as he returned and said no one there knew. I told him that I did and it worked great. We kept in touch for a couple of months to see if anything weird happened, which it didn't, and now it is suggested and common practice. Just as the Tech's and I whispered under our breath in the 90's about partitioning. Now they suggest it and Apple will talk to those that have partitioned. As you see needs and experiment you'll learn (trial by fire) and all this will become second nature. So don't think this is too much and go for it. Just make sure before you are completely comfortable, have another drive, I use 25GB Rewritable Blu-ray Discs, to do regular normal, CCC, back ups until you get the hang of it. This method yields 6-8GB compressed archives. Then you'll have a place for your stored back ups and whatnot. I was keeping up to 5 iterations, i.e.: 10.5.1a, b, c, d and e. Once my paranoia subsided I pared it down to two since I could easily recover the small amount that I have to now from small back ups that are mostly aliases relinking files that are safe on other partitions.
So yes you can put/clone the OS to another partition. Just make sure you cover your bases, use an application made for cloning/backing up (CCC) and label your installs as not to have the same name on two OS's or you'll have a bit of a problem off the top remembering which is which. I'm on 10.5.5C2.
Good Luck and Happy Partitioning.