RAID on Mac mini Server (2011 i7)

Question

I just purchased a new Mac mini Server today (the base configuration 2011 Quad Core i7 with 4GB RAM and 2x 500GB 7200RPM magnetic hard disks) and wanted to share what I've learned about setting up RAID on the system.
First, as you may have heard, the Mac mini Server does not include any installation/reinstallation media (I was hoping for a USB reinstall key, but it seems that the new systems don't include these or optical discs; last year's Mac mini Server included handy reinstall DVDs even though the system didn't have an optical drive).  Out of the box, the new Mac mini Server has Mac OS X Lion, the iLife suite, and the Mac OS X Lion Server tools pre-installed on one of the two 500GB internal drives; the other disk is formatted as a separate, second drive.
If this is the configuration you're looking for, you're good to go right out of the box.  As an aside, this shipping configuration is ideal for using the second disk as a Time Machine drive.  I would argue that Time Machine would be a better use of the second volume than a RAID 1 configuration, as Time Machine provides versioned backups and you don't incur the write performance penalty RAID 1 requires every time data is saved to the disk.  I would further caution that, while an internal Time Machine disk is a convenient safety measure, any critical data should be backed up outside of the system as well.
Now for those like me who were intrigued by the opportunity to mate the Quad Core i7 with a RAID 0/striped configuration for a performance boost (or if you want to use RAID 1), a RAID configuration is possible, but it there are a few caveats.
First, Apple has two recovery options for the new Macs: a small hidden recovery partition on the boot drive and their Internet Recovery system.  While it's possible to boot other systems from a Lion installation DVD extracted from the App Store Lion installer, such bootable optical discs will not boot the Mac mini Server at this time (this may change if Apple modifies the App Store Lion installer).  Therefore, as of right now, the recovery partition or the Internet Recovery system are the best options for installing/reinstalling on a RAID set.
Second, if you boot the system using Command+R to access the recovery partition, you can wipe the two drives and create a RAID set, but this process will remove the recovery partition and is incompatible with FileVault encryption (a warning to this effect comes up when you try to start an install/reinstalll on a RAID set, but at that point, you've likely already erased the recovery partition in Disk Utility).  If the system boots after the recovery partition is deleted, the only install/reinstall option is Apple's Internet Recovery.
Third, as might be expected depending upon your internet bandwidth, the Internet Recovery system can take a while to boot the recovery tools (10-15 minutes to boot on a standard cable modem connection) and to reinstall the OS (50+ minutes on a standard cable modem connection).  Internet Recovery currently reinstalls only Mac OS X Lion and the Server tools on the mini Server; there's no option to install iLife during the OS install (Apple could always change this by updating their servers, and there is a Customize button on the installer, but it is greyed out and cannot be clicked at the present).
Fourth, once the OS is reinstalled, it's possible to reinstall the iLife applications by launching the App Store from within Mac OS and selecting Purchased.  The store will indicate that the system is eligible to download the iLife apps and you can do so by agreeing to upload system-identifying information to Apple and signing in with your Apple ID.
I hope all this helps.  Here's a more concise step-by-step of how to set up the system with RAID:
THINGS YOU NEED
A fast Internet connection for the mini
Patience
Hold Command+R on the keyboard at start up to boot from the system's recovery partition (if the recovery partition has been deleted, the system should start from Apple's Internet Recovery system; you may need to connect to WiFi if wired ethernet isn't available)
Once you get into the recovery utility, select Disk Utility and for each of the two hard drives:
highlight the drive
select the Partition tab
select 1 Partition from the Partition Layout pulldown menu
select Free Space from the Format pulldown menu
click Apply
After you've wiped both of the drives, highlight one of the disks and click the RAID tab, then create a RAID set (striped or mirrored, as you prefer)
Quit Disk Utility and from the main recovery utility menu select Reinstall Lion (from this point on, if you have any trouble, you can restart the mini from the Internet Recovery system and return to this point, but the recovery partition will be gone as long as you keep the RAID set)
After you install and configure Mac OS X Lion Server (which can take well over an hour to download and install), you should be able to reinstall the iLife applications by launching the App Store App and selecting Purchased, then logging in with your Apple ID and agreeing to send your system info to Apple to download the iLife Applications
If you're using the mini as a production server, I highly suggest setting up some local, external recovery tool, as you don't want to have system downtime protracted by having to wait for an Internet Recovery boot/reinstall.  I would also beg Apple to consider this sort of scenario and to provide more supported methods for recovering and reinstalling from local media.
Best of luck to you all.

Answer 1

I found the basic principle on another forum thanks to a guy called 'e-whizz' and this what I did to make RAID 1 work on a mac mini server with LION server.
You can easily configure the second drive on a mac mini server for a Mirrored RAID 1 set with Lion Server without either reinstalling or erasing your existing setup.
The initial setup process takes about 30 minutes, though the rebuilding of the mirror disk will take several hours, depending on the amount of data you have on the drive. It took around 3 hours on a new mac mini server with lion server installed, nothing else configured.
Before you start, please ensure you have a current backup of the server. Getting the following commands wrong can render you server unusable.
What you need to use is the command line version of Disk Utility, diskutil.
Before you start, clone the hard drive. You can use SuperDuper (or similar, I have used SuperDuper) with copying all files onto a USB memory stick. If Lion is freshly installed, 8Gb will do. SuperDuper will create a bootable copy on the USB.
Boot the mac mini from the external USB. To do that, reboot and hold down the option key while restarting. You will see a window, select the USB drive to boot from.
Launch the terminal and type the following command:
diskutil list
This gives you a list of all the drives and partitions your system knows about.
You need to find the Server HD partition (the first disk) and the HD2 partitions (the second disk). These are the two main ~500GB drives. You will be using the disk IDENTIFIERs when issuing the diskutil commands. For a stock standard Mac Mini Server, the commands below are correct, but if you have previously changed the volume names, or repartitioned at any stage the disk identifiers and volume names may differ.
First enable RAID mirroring on existing Server HD volume. This will create a single disk, unpaired mirror, without affecting your data.
Using this syntax:
diskutil appleRAID enable mirror disktomirror
where disktomirror is your disk identifier for Server HD
On my mac mini server, Server HD was disk0s2, so I used this command:
diskutil appleRAID enable mirror disk0s2
You now need to run diskutil list again to see the disk identifier for the new RAID volume. The new RAID volume will be listed as disk# on its own at the bottom of the list.
On my mac mini server this was disk3 (disk 2 was the USB I booted from, disk 0 the first disk and disk 1 the second disk)
Next add the disk HD2 to the Server HD raid mirror volume (on my mac, as I said before, this is disk3) as a new member.
This step will erase disk HD2 and begin an auto repair of the Server HD.
Using this syntax:
diskutil appleRAID add member newdisk raidvolume
replacing newdisk and raidvolume with your particular disk identifiers
On my server this was:
diskutil appleRAID add member disk1s2 disk3
To follow the progress of rebuilding the mirror set, type
diskutil list
It will show you the progress in % of the rebuilding under status
Once finished, reboot and your RAID 1 is up and running and you have also a working backup on your USB (coz' that's where you booted from ;-)
After reboot you can check the status of your RAID with
diskutil appleRAID list
Both drives should show ONLINE under status, interestingly, the device node for the RAID changed on my mac mini server from disk3 to disk2
That's it