Everyone keeps essential data on their computers, and regardless of the hard drive or SSD you use, there is a danger that the disc will fail and cause data loss. For this reason, we always make backups. The challenge with backups is that you have to put the data they contain back into your computer. Instead, why not employ a fault-tolerant setup? RAID is a collection of several drives that can be configured to be fault resistant. So that your data is still accessible to you even if one or more of the discs in the RAID volume fail.
We’ll explain what RAID is in this post and show you how to use it to either safely backup your data or to speed up read/write operations on both internal and external discs.
What is RAID?
Redundant Array of Independent Disks is referred to as RAID. Before, it stood for Redundant Array of Inexpensive Disks to demonstrate that a number of cheap discs could perform on par with or even better than pricey, huge enterprise storage discs when they were RAIDed. But I digress.
RAID essentially enables the combination of two or more (thus the name Array) discs for uses like fail-safe backups, accelerated read/write speeds, and similar things.
RAID Levels
numerous types of RAID exist (or levels as they are called).
- RAID 1 : This level is called a mirrored RAID, and it does exactly what it sounds like. It mirrors the contents of one disk onto every single disk in the array. This means that if one or more of your disks fail, you can still recover all of the data as long as at least one disk in the array is functioning properly. This is possible because the data is copied on every disk in the array.
- RAID 0 : Also known as striping RAID, what this does is it combines multiple disks into one, larger volume. Data stored in such an array is almost equally distributed among all the disks in the array. This allows for faster reading and writing times. There is an issue however, if any one of the disks in your level 0 RAID fails, it becomes almost impossible to recover that data from the array because no disk has all of the data. This level is particularly useful for people who work with large files.
- CDS/JBOD: Concatenated Disk Set, also known as Just a Bunch Of Disks is not really a RAID setup. It simply allows you to concatenate a number of disks into one large logical volume. Say, for example, you had four 256 GB disks. CDS would allow you to concatenate them into one 1TB volume. This means that you will be able to save files onto these disks as if it was a single 1TB volume instead of four 256GB ones.
There are six of these, however only two can be used on Mac (there s a third option, but it s not really a RAID setup). Below is a description of them:
How To Setup RAID on Your Mac
Let’s get right into some RAID fun now that you have a basic understanding of what the different levels are.
Setting up RAID volumes was fairly easy prior to Apple’s release of OS X El Capitan. A straightforward option to RAID a number of drives into level 0, 1, or to concatenate the drives (CDS/JBOD) was available in the Mac’s graphical Disk Utility software. Apple discreetly eliminated the RAID option when they updated the disc utility in OS X El Capitan. We are not here to talk about why they did this. Instead, we are going to show you how to RAID your data on El Capitan.
Let’s start using our reliable Terminal app.
Thediskutilcommand has an appleRAIDsub-command for building RAIDs, it turns out.
The command’s syntax is:
Apple RAID create stripe|mirror|concat setName fileSystemType memberDisks in diskutil
You must decide which discs you want to RAID before we can start on the task.
1. Launch Disk Utility after connecting the discs to your computer.
2. Choose your discs from the left pane and write down the device property’s value. This must be entered in the Terminal.
- Replace setName with the name you want for your RAID volume.
- Set the fileSystemType to something like JHFS+, and in place of memberDisks type in the values you noted down in Step 2, leaving spaces between the names of each disk.
- For example, if you wanted to create a mirrored RAID with the name Backups and the device ids for your disks were disk2 , disk3 , disk4 , the command you ll have to type will be:
diskutil appleRAID create mirror Backups JHFS+ disk2 disk3 disk4.
3. Type diskutil appleRAID in the Terminal. setName fileSystemType memberDisks while creating a stripe/mirror/concat.
4. Substitute stripe (for RAID0), mirror (for RAID 1), and concat (for CDS/JBOD) for the keywords.
Ready To Create RAID Volumes on Your Mac?
5. After the command has finished running, you can discover your RAID volume in Disk Utility and OS X will immediately mount it.
