Basics of RAID
RAID (Redundant Array of Independent Disks) configurations use multiple SSDs or hard drives. They can provide duplication of data so no files are lost in the event of a drive failure (called "mirroring"). They can also provide parallel operation so that read and write operations can be split across devices to increase performance as multiple disks can be used at once for a given operation (called "striping"). These arrays work best when all connected drives are identical, but in many RAID environments different disks can be used. Performance and capacity differences across connected drives reduce performance and usable capacity in every disk in the array to that of the lowest performing part.
RAID descriptions include a number as shorthand for what kind of operation the collection of disks is configured for, with a striped array being commonly referred to as RAID 0 and a mirrored array as RAID 1. Additional types exist when a combination of striping and mirroring are used, such as RAID 10, RAID 5, and RAID 6. The differences between these arrays are in how many disks are required and how they are used to boost performance while allowing for one or more drives to be lost before data loss occurs.
RAID can be hardware or software-based. Hardware RAID uses a dedicated RAID controller to manage the installed drives and software RAID uses software within your installed operating system to do the same. Software RAID is generally cheaper to configure and use, but investing in dedicated hardware to set up RAID reduces CPU and other system resource usage to manage the array. Steps to configure RAID vary depending on the exact type being set up, but generally an array is configured in a RAID adapter's firmware utility or your system's UEFI or BIOS, then an operating system looks at the array as a destination to partition and begin writing data to, either installing an operating system to the RAID or using it as a secondary volume. Refer to support for your motherboard, operating system, or dedicated RAID adapter for detailed instructions on setup and management.
In terms of day-to-day use, RAID works similarly to a single disk, but diagnostic tools read data from a RAID configuration differently than they do a single SSD or hard drive. For example, Crucial Storage Executive is not fully compatible with some RAID controllers and configurations, and specific functions such as SMART reporting or firmware updates may not work at all in these unsupported environments, requiring the RAID to be temporarily disassembled for updates or troubleshooting of individual drives. Also, while modern operating systems and RAID drivers allow trim commands to run on SSDs in RAID, legacy operating systems and drivers may not properly support them, meaning functions such as Garbage Collection become more important for maintaining the highest performance from connected SSDs.
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