How to Do a Clean Install of Lion Server

By John Rizzo from Mac OS X Lion Server For Dummies

In most cases, the Lion installer doesn’t give you the option to erase the drive or partition on which you’re installing, which means you should do any erasing before you start the installation process.

But doing a clean install of Lion may mean that you will be doing two installations of Mac OS X. That’s because to install Lion onto a blank disk or partition, you need to boot the Mac from a second drive partition, or even USB flash RAM, running Mac OS X 10.6 or 10.7.

So if you don’t have Mac OS X 10.6 or 10.7 on storage device that you can attach to the Mac, you will have to install it.

In order to reformat or partition a hard drive, you need to boot the Mac from another drive and run Disk Utility. Erasing a drive in Disk Utility is similar to partitioning. Both destroy any existing data on the drive.

Erasing a volume simply wipes the data off it. Partitioning a hard drive divides it into multiple volumes. Each volume appears as a separate hard drive to the user. You can use one partition as the startup disk containing Mac OS X Server (the operating system and services) and use another, larger partition to store the user files.

If something goes wrong with the user data volume, the server can keep functioning — or at least it won’t have to be re-created. This scheme also prevents the boot partition from running out of disk space because of growing user data.

Having multiple drives gives you better system performance than multiple partitions. But if have a 500 GB or larger startup disk and plan on storing user data elsewhere, you’ll have a lot of wasted space if you don’t partition.

One essential thing to remember about partitioning: You must use the default GUID Partition Table, not the Apple Partition Table. If you use the latter, you won’t be able to boot from the drive.

You also need to choose a format. There are two formats you can use for a startup disk:

Mac OS Extended (Journaled): Most people use this standard format.
Mac OS Extended (Case-sensitive, Journaled): Some people who are hosting static websites use this format because it improves performance, with a better mapping between URLs and files.

For drives that you won’t use as startup disks, you can use the nonjournaled versions of these two formats, though there isn’t a compelling reason to do so.

To partition a drive, either before or during installation, do the following:

Launch Disk Utility from /Applications/Utilities.
Click the hard drive you want to partition in the left pane.

The drive is the leftmost item; a partition on the drive is indented.
Click the Partition tab.
In the Volume Scheme pop-up menu, choose the number of partitions you want to create.

The space below the pop-up menu has a number of boxes representing the partition sizes.
Drag the bar that separates the boxes to resize them to the partition size (in gigabytes) that you want for each.
Click a box to select it and then type a name for it in the Name field for each partition.

For example, the names Boot Partition and User Data.
In the Format pop-up menu, make sure that Mac OS X Extended (Journaled) is selected.
At the bottom of the window, check that GUID Partition Table is selected for Partition Map Scheme.

If not, click the Options button and select GUID Partition Table.
Click Apply.

Erasing is simpler. Select the drive or volume from the column on the left and click the Erase tab. Choose a format from the Format pop-up menu and click the Erase button.