Because each disk has less to do and writes to each disk occur concurrently, it takes less time to write the data. The same is true when reading data; instead of a single disk having to seek out and then send a large block of data, multiple disks each stream their part of the data stream. As a result, RAID 0 striped sets can provide a dynamic increase in disk performance, resulting in faster OS X performance on your Mac.
Weighing the Benefits
Of course, with an upside (speed), there is almost always a downside. In this case, an increase in the potential for data loss caused by a drive failure. Since a RAID 0 striped set distributes data across multiple hard drives, the failure of a single drive in the RAID 0 striped set results in the loss of all data on the RAID 0 array. Because of the potential for data loss with a RAID 0 striped set, it is highly recommended that you have an effective backup strategy in place before you create the RAID 0 array. A RAID 0 striped set is all about increasing speed and performance. This type of RAID is a good choice for video editing, multimedia storage, and scratch space for applications, such as Photoshop, that benefit from faster drive access. It’s also a good choice for speed demons out there who want to achieve high performance just because they can.
What You Need to Create a RAID 0 Striped Set
The process of creating a RAID set is relatively simple and doesn’t take much time. However, erasing all the drives in the RAID set — especially if you use the Zero Out Data option — can be a time-consuming process. In macOS Catalina (10.15) through macOS Sierra (10.12), DIsk Utility support for RAID returned, but the process differs from the one shown here. See how macOS Disk Utility creates RAID arrays. To create a RAID 0 striped array, you need a few essential components.
Disk Utility, which is included with OS X. Two or more hard drives. The process of creating RAID 0 striped sets erases all the data on the hard drives. It’s best if the hard drives you use are the same make and model, but this is not a requirement. One or more drive enclosures. Mac Pro users may have internal drive bays available. Everyone else needs one or more external drive enclosures. If you are using multiple drive enclosures, they should have the same type of interface, such as FireWire, USB, Thunderbolt, or SATA.
Erase the Drives Using the Zero out Data Option
The hard drives you use as members of the RAID 0 striped set must first be erased. A RAID 0 set can be severely affected by a drive failure, so take extra time and use one of Disk Utility’s Security Options — Zero Out Data — when you erase each hard drive. When you zero out data, you force the hard drive to check for bad data blocks during the erasure process and mark any corrupt blocks as not to be used. This decreases the likelihood of losing data due to a failing block on the hard drive. It also significantly increases the amount of time it takes to erase the drives from a few minutes to an hour or more per drive. Here’s how to erase the drives:
Create the RAID 0 Striped Set
After you erase the drives you plan to use, you’re ready to start building the striped set.
Add Slices to Your RAID 0 Striped Set
With the RAID 0 striped set now available in the list of RAID arrays, it’s time to add drives — referred to as slices — to the set. After you add all the hard drives to the RAID 0 striped set, you are ready to create the finished RAID volume for your Mac to use. During the creation of the RAID 0 striped set, Disk Utility renames the individual volumes that make up the RAID set to RAID Slice. It then creates the actual RAID 0 striped set and mounts it as a single hard drive volume on your Mac’s desktop. The total capacity of the RAID 0 striped set you create is equal to the combined total space offered by all members of the set, minus some overhead for the RAID boot files and data structure. Close Disk Utility and use your RAID 0 striped set as if it were any other disk volume on your Mac.
Back up Your New RAID 0 Striped Set
Now that you have finished creating your RAID 0 striped set, here are a few tips about its use. Once again, the speed provided by a RAID 0 striped set does not come free. It is a trade-off between performance and data reliability. The loss of any single drive causes all data on the RAID 0 striped set to be lost. To be prepared for a drive failure, you need a backup strategy that goes beyond the occasional backup. Consider the use of backup software that runs on a predetermined schedule. A RAID 0 striped set can significantly boost your system’s performance, and it is a great way to increase the speed of video editing applications, specific applications such as Photoshop. Even games are faster if the games are i/o bound — they wait to read or write data from your hard drive. After you create a RAID 0 striped set, you won’t have any reason to complain about how slow your hard drives are.
