Create a Leopard to Snow Leopard Upgrade NetInstall Image

UPDATE (10/15/09): I’ve gotten mixed results from some individuals who’ve tried the workaround with 10.6.1. I’m working on and testing an extended workaround that should fix the problem for everyone. Look for that info soon.

— — — —

UPDATE (10/13/09): I’ve updated the article (and posted it as new) with a workaround for the issue that prevented additional packages from being installed. I submitted the bug that this workaround avoids to Apple — id #7247968 — on September 23, 2009.

— — — —

This post is a Snow Leopard update to a process I wrote about when Leopard (10.5) came out. This post will tell you how to create a NetInstall image that will upgrade a Mac running Leopard to the latest version of Snow Leopard in one step. It will also work to upgrade a Mac running Tiger to the latest version of Snow Leopard.

What You’ll Need

1. A 10.6 software license, or individual retail copy of Leopard, for each computer you are upgrading from Leopard or Tiger to Snow Leopard — this is easily overlooked, so let’s keep things legal.
2. A read/write disk image (.dmg) of a Mac OS X v10.6 Snow Leopard Install DVD (i.e. not shipped with a computer). You’ll convert this to read-only after making a small modification to one of the files.
3. One build computer running Snow Leopard with the latest version of Snow Leopard’s Server Admin Tools installed (10.6.0 as of this writing).
4. A computer running OS X Server providing NetBoot services — Tiger, Leopard, and Snow Leopard Server will all work
5. A copy of the OSUpgrade.pkg found on the Install DVD at /Volumes/Mac OS X Install DVD/System/Installation/Packages. This is a hidden folder, so use Go to Folder from the Finder’s Go menu to reveal it.
6. Optional: the latest Combo Updater — 10.6.1 as of this writing. (Yes, it’s not a Combo Update, but only because it’s a .1 updater.)

I. Make a Read-Write Installer Disk Image

As of Mac OS 10.5.7, there has been a bug in in the OS installer that prevents you from successfully adding sizeable packages to your System Image Utility. Fortunately, there is a workaround. I’ll walk you through how to implement it here.

1. Insert the OS Install DVD into your drive and then launch Disk Utility (found in /Applications/Utilities).
2. Select the Install DVD from the list on the left, then click the New Image icon in the toolbar.
3. Rename the image if you like, choose a location to save it, and change the Image Format option to read/write. Click Save to create the read/write disk image.
4. When the disk image is done, eject the DVD, select the disk image on the left side of the window, and click the Open icon in the toolbar to mount it.

II. Modify the Disk Image

The reason we need to modify the disk image is because, since 10.5.7, the System Image Utility can’t properly handle additional packages that you add into your workflow. During startup — whether from DVD or via NetBoot — the installer creates a RAM disk to hold the contents of the /private/var directory. This is where additional packages get placed. The RAM disk size specified by Apple’s installer is too small to hold anything buy payloadless packages. The following instructions walk you through changing the size of this RAM disk to better accommodate additional packages.

1. Open Terminal, navigate to the /etc/ directory on the disk image and open the rc.cdrom file in your favorite text editor. This file is marked as read-only, so I like to use vi as it allows you to easily write to read-only files. This command will open the file in vi:
   vi /Volumes/Mac\ OS\ X\ Install\ DVD/etc/rc.cdrom
2. The line you’ll need to modify is ‘RAMDisk /var/run 1024’. Change 1024 to 1048576 and force vi to write the read-only file. 1048576 is equivalent to 512mb — we’re specifying sectors, which are 512 bytes each — which should be sufficient for any additional packages you want to include in your upgrade NetInstall image. If your vi skills are rusty or missing, follow these step to make this change.
   1. Use the arrow keys to move the cursor down to the ‘RAMDisk /var/run 1024’ line and onto the 1 in 1024.
   2. Type cw — short for “change word”. The 1024 will disappear and vi will enter insert mode, which allows you to add characters to the file.
   3. Type 1048576
   4. Press the Esc key to exit insert mode.
   5. Type :x! to force the read-only file to be saved and exit vi.
3. Exit Terminal.

III. Convert the Disk Image to Read-only/Compressed

1. Go back to Disk Utility, select the mounted disk image on the left side of the window and click the Unmount icon in the toolbar.
2. Select the disk image and click the Convert icon in the toolbar.
3. Choose compressed from the Image Format menu. Rename the disk image so you know it’s the one you’ve modified, or save it in a different location from your read/write image. Click Save to begin the conversion.
4. Exit Disk Utility after the conversion is complete.

Keep this disk image in a safe place as you’ll be able to re-use it when you want to create an updated NetInstall image — say when the 10.6.2 Combo Update is released.

IV. Build your NetInstall Image

If you haven’t yet made a DMG from the Mac OS X v10.6 Leopard Install DVD, do it now. (I use Disk Utility to create a default compressed image.) Mount the disk image and then launch the System Image Utility found in /Applications/Server. The program will auto-detect the mounted disk image as a source and select the NetInstall Image build option.

Click Customize at the bottom of the window to bring up the workflow assembly interface.

The idea here is to drag and drop the components you want from the Automator Library window to the workflow area. The Define Image Source item is added for you at the top, with the Create Image item below it. We’re going to build the simplest possible custom upgrade image, so we’ll add only one more item to our workflow.

First, select the Add Packages and Post-Install Scripts item and drag it over in between the two existing items. Now go to the Finder and locate the OSUpgrade package. and the latest Combo Updater for Snow Leopard. You’ll have to grab the package from the mounted update dmg. (10.6.1 isn’t a combo update since there are no previous updates, but it will work just fine.) Drag the package into the list area of the Add Packages and Post-Install Scripts item.

Then, in the Create Image item at the bottom of your workflow, make sure the NetInstall option is selected in the Type section. Click the Save To drop down and select Other. Select your boot drive from the Devices list in the sidebar and click Open. (You can save directly to a network volume if you want to save yourself a step later, but I like to save mine locally so a network hiccup won’t interrupt the image build process.)

You can probably ignore the Installed Volume field since we’re working on an upgrade, but you can supply the standard volume name of the Macs you manage here. In the Image Name field, enter a descriptive name. In the Network Disk field, enter a name that you’d like the NetInstall set to be advertised as on the network. (If your network is set up to advertise your NetBoot server across the network, your NetBoot/NetInstall volumes will appear in the Startup Disk preferences pane of all the Macs on your network.) Enter a Description if you wish, and then enter a unique Index number. Choose a number between 1-4095 if you have a single NetBoot server. Choose a number between 4096-65335 if you have more than one NetBoot server in a load-balanced configuration.

Now click Save to save the workflow. When a new Combo Updater comes out later, you’ll be able to use this workflow and just drag that package in — removing any older Combo Updaters, of course.

To build the image, click Run. In a few moments, you’ll be asked for your admin credentials, after which the build process will begin. If you want to track the progress, go to the View menu and select Show Log. This is a relatively quick build, so hang around unless you really need a coffee. It should take well under 30 minutes, and as little as 10 with recent hardware.

It’s done! Now what?

Ok, so your NetInstall image was created successfully. All that’s left to do now is to copy it to your server’s (or servers’) NetBootSPx share(s). (I have mine shared via AFP, but your environment may be different.) After you’ve transferred it, use Server Admin to enable the new NetBoot image. Assuming your network is set up in a NetBoot-friendly way, you should now be able to upgrade any Mac under your control from Leopard (or Tiger) to Snow Leopard by booting it with this NetInstall image.

Don’t forget to test, test, test before using this in production.

Get a Twitter Account’s Registration Date via Snow Leopard Service

Creating services in Snow Leopard is all the rage lately. So is Twitter. This tutorial brings both of them together and should serve as a fine example of just how slick and useful services in Snow Leopard can be.

Can I boot Snow Leopard in 64-bit mode?

UPDATE: Please read Update 2 at the bottom of this post before using a 64-bit kernel as your default.

---

With Snow Leopard making its appearance this Friday, August 28, 2009, some people may be wondering whether they’ll be able to boot their Macs in 64-bit mode. Only Intel Xserves will boot this way by default. If you want to boot your desktop or mobile Mac in 64-bit mode, you’ll need to take some additional steps. The first is checking to see if your Mac has a 64-bit-capable EFI. If the output of the following command is EFI64, you’re good. If not, you’re out of luck.

    ioreg -l -p IODeviceTree | awk -F'"' '/firmware-abi/{print $4}'

Once you’ve verified it’s possible, you have a couple options for making your Mac boot into 64-bit mode. I’d try them in this order. First, to affect the current boot only, hold down the ‘6′ and ‘4′ keys during bootup. Once you’ve verified it works and are comfortable with it, you can make the change permanent by adding an ‘arch=x86_64′ boot flag to your com.apple.Boot.plist, like so:

    sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.Boot 'Kernel Flags' 'arch=x86_64'

---

UPDATE 1 (8/28/09): Apple has a couple new (and one older) knowledge-base articles pertaining to this topic.

1. Mac OS X Server v10.6: Macs that use the 64-bit kernel
2. Mac OS X Server v10.6: Starting up with the 32-bit or 64-bit kernel
3. How to tell if your Intel-based Mac has a 32-bit or 64-bit processor

---

UPDATE 2 (8/29/09): This post has received quite a few hits, so I now feel the need to include some educational material about why Apple chose to make Snow Leopard boot with a 32-bit kernel by default.

The primary reason is for compatibility with third-party software, particularly software that requires kernel extensions. Probably the most widely know examples of software that depends upon kernel extensions, or kexts, are VMware Fusion and Parallels. If you use these to run Windows or Linux on your Mac, you’ll want to keep using a 32-bit kernel. Virtualization software needs direct access to the hardware normally controlled by the kernel (CPU, RAM, Disk) in order to “fool” operating systems into thinking they’re installed on “real” computers. The kernel extensions allow them to do this.

Kexts must be written specifically for 32-bit or 64-bit kernels. They are not interchangeable. Applications, on the other hand, can run at 64-bit even if the kernel is 32-bit. As far as your 64-bit CPU is concerned, the kernel is just another application. It’s a very important application — in the sense that it is code that is executed on a processor — whose job it is to arbitrate demands on the system’s resources. Most applications don’t have direct access to the CPU, RAM, or other physical devices, but make requests of the kernel instead.

---

UPDATE 3 (9/1/09): John Siracusa’s new article on Snow Leopard was posted today. Then entire thing is great reading, but I’m linking to the section that addresses 64-bit vs 32-bit here.

Create a Tiger to Leopard Upgrade NetInstall Image

(UPDATE: If you’re interested in a Snow Leopard upgrade process, please see this post for updated instructions.)

adminertia : an admin at rest tends to stay at rest and an admin in motion tends to want to return to rest as soon as possible.

When Leopard was first released, I was almost grateful that it didn’t work reliably with Active Directory since that flaw provided me with a valid excuse for not having an upgrade procedure ready to roll when upgrade requests started trickling in from my users. I knew that by the time Apple got around to releasing an update that made Leopard work well with AD, the number of requests would have increased significantly. I needed to have a method of handling them in a timely manner.

Walking around the building with an installer DVD or a FireWire drive in hand doesn’t exactly rank as timely, nor does it rank as anything close to what I want to be doing with my time. NetBooting from a copy of the installer DVD is a slightly better option, but that would require applying a handful of OS and security updates after the initial install in order to bring each computer up-to-date. NetBooting with a NetRestore set created with Mike Bombich’s (otherwise) excellent software is not an option because it can’t upgrade a computer, only overwrite it.

Because I have chosen not to use Radmind in my environment, it seemed my options for creating a more or less automated upgrade to take Macs running 10.4.x directly to the latest version of Leopard were severely limited. After much despair, head scratching, and a little behind-the-scenes investigation, I discovered that Leopard’s System Image Utility could be wrangled to accomplish my goal.