RAID 0 is a popular disk setup solution to achieve the fastest possible read and write disk speeds by splitting data between two or more hard drives. The latest version of Mac OS X High Sierra (10.13) does not allow you to simply install to any kind of RAID configuration. This has frustrated a lot of the Mac community. Until Mac OS X High Sierra officially supports RAID configurations, follow the steps below to setup a fully functional RAID 0 configuration.
*You will notbe able to install system updates from the App Store on your live RAID volume. However, see our workaround at the end of guide. *
In order to install the latest version of Mac OS X onto a RAID 0 slice, you must clone a copy of your Mac OS X installation straight to the RAID 0 drives (not a restore, such as Time Machine, which will not work). To accomplish this, you need an external hard drive and a copy of SuperDupersoftware in addition to your RAID 0 drives. We will use the same Mac machine (that will use RAID 0) to perform all the steps below. This method uses hardware RAID and is not a software RAID.
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Note: We strongly recommend taking a full backup (Time Machine) to another drive just in case when performing these steps! Save yourself from an accident!
Note: Be sure to complete your SuperDuper clones on the same type of Mac you will install the RAID 0 configuration on. This is important because your Mac OS High Sierra clone will have drivers and system files specific to that machines hardware.
Open Disk Utility in Applications -> Utilities and create your RAID 0 array shown below.
Go to File -> RAID Assistant
Select Striped (RAID 0)
Select your 2 internal hard drives to create the RAID array from
Name your single RAID drive. For Chunksize, choose a lower size if you will be using the RAID for regular needs (email/browsing/word processing.) For video editing, choose a higher chunk size.
Success screen appears
The copy will complete successfully. Finally, go to System Preferences -> Startup Disk and select your new drive and restart. The first restart may take a little time as your boot files load for the first time.
You can confirm your successful RAID 0 in Disk Utility.
If system updates are available in the app store they will appear, but do not attempt to install them. Your computer will fail installing them and you will likely damage your OS installation! App Store Application updates will install OK. See below workaround.
Now you have the latest Mac OS X system updates installed on your RAID O configuration drive again. The entire process took us under 1 hour using SSD drives and USB 3.0.
Setting up a software RAID (or random array of independent disks) is a great way to inexpensively provide a huge boost to read/write speeds, or add an internal back up solution (or do both!).
All you need is a Mac with the ability to install more than one SSD or HDD (such as a Mac Pro 5,1) and some HDDs or SSDs, we recommend using matched drives in most cases, however, simply matching capacity (2TB etc.) and type (HDD or SSD) is usually fine.
A RAID is basically a collection of physical drives, linked together, that are seen by your system as a single drive. You can set up a RAID in a number of different ways. A striped RAID will boost read and write speeds by splitting your data between all 4 drives and reading/writing to them all at the same time. A mirrored RAID will write the same data to a number of drives, meaning you have real time back-ups that are fully bootable and can repair themselves. You can even set up 2 striped RAIDs in a mirrored RAID. This may sound confusing, but we’ll explain which configuration is best for what soon enough.
Setting up a striped RAID is a great option when you need to maximise read & write speeds, regardless of your budget. Theoretically you could set up a striped RAID using 4 PCI-E flash storage blades in an external PCI-E expander, you would hit around 4GB/s read & write speeds with a set up like this, but it wouldn’t be cheap. Alternatively, you could use 4 HDDs in a Mac Pro’s internal HDD bays and hit speeds of around 600MB/s, about 20% faster than the best consumer 2.5″ SSDs, but the cost would be much less. There are also a myriad of options in-between for every budget, you don’t have to use 4 drives, a 2 drive RAID is still extremely effective.
A striped RAID will have disk read & write speeds that are around the sum total of your drives separately. So if you use two 500MB/s SSDs then your RAID will read & write at around 1GB/s.
How to:
With a bootable USB installer, you can even install OS X on your new RAID set. You can also use Disk Utility when booting from the USB installer to create a RAID set without having to have another OS X drive for Disk Utility, extremely useful when creating a 4 drive RAID in a Mac Pro.
With a striped RAID set it is essential that you keep a back-up. Should one of the drives in your RAID fail, the whole RAID will fail.
Setting up a mirrored RAID set is a great internal back-up solution, providing a real-time back-up that can even automatically repair itself should a drive fail, this is achieved by writing your data to both disks rather than just one. Again we would recommend using matched drives, but you don’t have to.
You can use SSDs, HDDs and even PCI-E flash storage, it all depends on your needs and budget. You can also use as many disks as you like, you shouldn’t need more than 2, but using 3 or 4 will give you even more security should a drive fail.
How to:
You’re now all set to install OS X on your mirrored RAID set, or to just use it as a data drive. Again use a bootable USB installer if you have no other drives to install from.
Want the speed of a striped RAID set as well as the security of a mirrored RAID? If so, RAID 10 might be the one for you. A RAID 10 set comprises of two mirrored RAID sets in a striped RAID formation. Should a drive fail, it will auto repair, and you will still get the speed boost of striping (4 drives in a RAID 10 formation will read/write at double the speed of a single drive as opposed to 4 times the speed with a pure striped RAID).
For example, using 4 HDDs in a RAID 10 set will achieve read & write speeds of around 300MB/s as well as having real time back-up and auto repair functionality.
Technically this isn’t actually a RAID 10 set, as a RAID 10 set is a hardware RAID. But it is a software clone and does exactly the same thing. You can call it a mirrored-striped-software-RAID-set if you like.
How to:
Again, you can now install OS X on your mirrored striped RAID set, or simply use it as a data drive.
You can also set up a striped mirrored RAID set (as opposed to mirrored striped), just set up two mirrors and stripe those together instead. Functionality and performance will be the same.
As with any storage drive, you should always keep a physical or online back-up of your RAID set, regardless of the type. In most cases software RAID sets are very reliable, but they can be susceptible to things such as power cuts, again unlikely, but the possibility is always there even with a mirrored RAID.
And remember, it’s not really a back-up unless you have two.
We do also provide hardware RAID controllers for the Mac Pro 5,1 at Create Pro. Complete with on board battery and controller for extra security.