Disk Utility User Guide
You can create a Redundant Array of Independent Disks (RAID) set to optimize storage performance and increase reliability in case of a disk failure. You can also create a set that concatenates smaller disks to act as one larger disk.
In the Disk Utility app on your Mac, choose File > RAID Assistant.
Select a set type:
Striped (RAID 0) set: A striped RAID set can speed up access to your data. You can't create a RAID set on your startup disk; you must first start up your computer from another disk.
Mirrored (RAID 1) set: Protect your data against hardware failure with a mirrored RAID set. When you create a mirrored RAID set, your data is written to multiple disks so the information is stored redundantly. You can't create a RAID set on your startup disk; you must first start up your computer from another disk.
Concatenated (JBOD) set: Increase storage space with a concatenated disk set. If you need one large disk, but you have several smaller disks, you can create a concatenated disk set to use as one large disk.
Select the checkboxes of the disks you want to include in the set.
For each disk, click the pop-up menu in the Role column and choose 'RAID slice' or 'Spare' to designate the disk as a standard member or spare in the set, then click Next.
Enter a name for the RAID set in the RAID Name field.
Click the Format pop-up menu, then choose a volume format that you want for all the disks in the set. (See File system formats available in Disk Utility.)
Click the 'Chunk size' pop-up menu, then choose a disk chunk size that you want used for all the disks.
When you create a striped set, chunks of data from the same file are distributed across the drives. Ideally, you want data distributed across drives evenly and at an optimum size so that it can be efficiently accessed. If you want high data throughput from your set, choose a smaller chunk size so that data is spread across the drives and one drive can be accessing data while another is seeking the next chunk. With mirrored disk sets, choose a chunk size that matches the data you're accessing. For example, when working with video files, your Mac is accessing large chunks of data, whereas when using a database of many small records, your disks may be accessing smaller chunks of information.
If you are creating a mirrored RAID set, select the 'Automatically rebuild' checkbox to allow the set to be automatically rebuilt when member disks are reconnected.
Click Create.
Click Done.
If you have a Mac Pro with a Mac Pro RAID card, use RAID Utility. It uses the RAID card for better performance and to create more types of RAID sets.
List of all WD firmware and software available for download. Our Download Center provides PROMISE customers with the latest firmware and utilities updates as well as technical briefs, compatibility lists, manuals, guides, data sheets, etc. SoftRAID is the powerful and intuitive software RAID utility for macOS and Windows that offers maximum volume capacity, optimum drive performance, data protection, or a combination of attributes via selectable RAID levels.
Disk Utility User Guide
You can combine multiple disks into one disk set—called a Redundant Array of Independent Disks (RAID)—and they will work together as one. Depending on how you combine the disks, the RAID set can protect your data against hardware failure, speed up access to your data, or increase your storage capacity. You can use Disk Utility to create several different types of disk sets with both internal and external disks.
Striped RAID set (RAID 0)
You can combine multiple hard disks into a striped RAID set to provide faster disk access. For example, in a striped RAID set composed of three disks, data is distributed between all the disks and three disks write and read that data simultaneously, giving you faster access. A striped RAID set is especially useful for quickly accessing large files, such as digital video and database files. A striped RAID set works best if the disks are about the same size and are connected to your computer via fast connections.
If the disks are different sizes, a striped RAID set treats all the disks as if they are the size of the smallest one. If you have disks of different sizes, you might want to use a concatenated disk set (see below), which doesn't give you the speed advantage of a striped RAID set, but lets you use the full capacity of all its disks.
If the disks are connected to the computer with slow connections, such as USB connections, you might not get faster disk access with a striped RAID set. For best results, use internal disks or disks with fast connections.
Mirrored RAID set (RAID 1)
Raid Drive Mac
A mirrored RAID set can help protect your data against disk failure. Each disk in the set stores the same data, similar to having multiple backup disks. Your data is written on two or more disks at once, so if a disk fails or is disconnected, your Mac can still access the data from the other disks. If you reconnect a disk that was temporarily disconnected, the RAID set can rebuild the reconnected disk so that it contains the same data as the other disks.
You can also add spare disks to a mirrored RAID set. A spare disk isn't used unless another disk fails or is disconnected. When a disk fails or is disconnected, the RAID set switches to use a spare and rebuilds it to contain the latest data. If you reconnect a disk after the RAID set replaced it with a spare, the reconnected disk is treated as a spare.
Even if you have a mirrored RAID set, you still need to back up your data regularly. Mirroring protects you from some types of hardware failure, but not from user errors or software corruption. If you delete a file, it's deleted from the mirror as well. If software corrupts a file, it's also corrupted on the mirrored disks.
Best Raid Software For Mac
Concatenated disk set (JBOD)
A concatenated disk set, also called 'Just a Bunch of Disks' (JBOD), combines several smaller disks into a single large disk.
A concatenated disk set is helpful if you have a file, such as a database, that's larger than any of your disks. You can use Disk Utility to add more disks to a concatenated disk set to increase its size.
You can also use a concatenated disk set to create a mirrored or striped RAID set with disks that are different sizes. Because mirrored or striped RAID sets store data most efficiently using disks that are roughly the same size, you might concatenate two smaller disks into a set that matches the size of another large disk, and then combine the concatenated set and the large disk into a mirrored RAID set. (If all the disks in the set are about the same size, consider using a striped RAID set, which lets you access your data more quickly.)
Best Raid Storage For Mac
RAID disk sets cannot use some disk management features, such as FileVault disk encryption.
List of all WD firmware and software available for download. Our Download Center provides PROMISE customers with the latest firmware and utilities updates as well as technical briefs, compatibility lists, manuals, guides, data sheets, etc. SoftRAID is the powerful and intuitive software RAID utility for macOS and Windows that offers maximum volume capacity, optimum drive performance, data protection, or a combination of attributes via selectable RAID levels.
Disk Utility User Guide
You can combine multiple disks into one disk set—called a Redundant Array of Independent Disks (RAID)—and they will work together as one. Depending on how you combine the disks, the RAID set can protect your data against hardware failure, speed up access to your data, or increase your storage capacity. You can use Disk Utility to create several different types of disk sets with both internal and external disks.
Striped RAID set (RAID 0)
You can combine multiple hard disks into a striped RAID set to provide faster disk access. For example, in a striped RAID set composed of three disks, data is distributed between all the disks and three disks write and read that data simultaneously, giving you faster access. A striped RAID set is especially useful for quickly accessing large files, such as digital video and database files. A striped RAID set works best if the disks are about the same size and are connected to your computer via fast connections.
If the disks are different sizes, a striped RAID set treats all the disks as if they are the size of the smallest one. If you have disks of different sizes, you might want to use a concatenated disk set (see below), which doesn't give you the speed advantage of a striped RAID set, but lets you use the full capacity of all its disks.
If the disks are connected to the computer with slow connections, such as USB connections, you might not get faster disk access with a striped RAID set. For best results, use internal disks or disks with fast connections.
Mirrored RAID set (RAID 1)
Raid Drive Mac
A mirrored RAID set can help protect your data against disk failure. Each disk in the set stores the same data, similar to having multiple backup disks. Your data is written on two or more disks at once, so if a disk fails or is disconnected, your Mac can still access the data from the other disks. If you reconnect a disk that was temporarily disconnected, the RAID set can rebuild the reconnected disk so that it contains the same data as the other disks.
You can also add spare disks to a mirrored RAID set. A spare disk isn't used unless another disk fails or is disconnected. When a disk fails or is disconnected, the RAID set switches to use a spare and rebuilds it to contain the latest data. If you reconnect a disk after the RAID set replaced it with a spare, the reconnected disk is treated as a spare.
Even if you have a mirrored RAID set, you still need to back up your data regularly. Mirroring protects you from some types of hardware failure, but not from user errors or software corruption. If you delete a file, it's deleted from the mirror as well. If software corrupts a file, it's also corrupted on the mirrored disks.
Best Raid Software For Mac
Concatenated disk set (JBOD)
A concatenated disk set, also called 'Just a Bunch of Disks' (JBOD), combines several smaller disks into a single large disk.
A concatenated disk set is helpful if you have a file, such as a database, that's larger than any of your disks. You can use Disk Utility to add more disks to a concatenated disk set to increase its size.
You can also use a concatenated disk set to create a mirrored or striped RAID set with disks that are different sizes. Because mirrored or striped RAID sets store data most efficiently using disks that are roughly the same size, you might concatenate two smaller disks into a set that matches the size of another large disk, and then combine the concatenated set and the large disk into a mirrored RAID set. (If all the disks in the set are about the same size, consider using a striped RAID set, which lets you access your data more quickly.)
Best Raid Storage For Mac
RAID disk sets cannot use some disk management features, such as FileVault disk encryption.
Note: If you have a Mac Pro with a Mac Pro RAID card, use RAID Utility. It uses the RAID card for better performance and to create more types of RAID sets.
