RAID 0+1 is similar to RAID 1+0, except the data organization method is slightly different. It offers the best performance, but it does not provide fault tolerance. This configuration has striping but no redundancy of data. The number of levels has since expanded and has been broken into three categories: standard, nested and nonstandard RAID levels. This numbered system enabled those in IT to differentiate RAID versions. The original paper that coined the term and developed the RAID setup concept defined six levels of RAID - 0 through 5. RAID devices use different versions, called levels. Firmware-based RAID is also called hardware-assisted software RAID, hybrid model RAID and fake RAID. A firmware RAID controller is not as pricey as a hardware option, but it puts more strain on the computer's CPU. Once the OS has loaded, the controller driver takes over RAID functionality. However, with firmware, the RAID system is only implemented at the beginning of the boot process. If a software-based RAID implementation is not compatible with a system's boot-up process and hardware-based RAID controllers are too costly, firmware, or driver-based RAID, is a potential option.įirmware-based RAID controller chips are located on the motherboard, and all operations are performed by the central processing unit (CPU), similar to software-based RAID. While it performs the same functions as a hardware-based RAID controller, software-based RAID controllers may not enable as much of a performance boost and can affect the performance of other applications on the server. With software-based RAID, the controller uses the resources of the hardware system, such as the central processor and memory. A physical RAID controller can also be built into a server's motherboard. The controller can also be designed to support drive formats such as Serial Advanced Technology Attachment and Small Computer System Interface. In a hardware-based RAID product, a physical controller manages the entire array. Using a RAID controller can improve performance and help protect data in case of a crash.Ī RAID controller may be hardware- or software-based. It can be used as a level of abstraction between the OS and the physical disks, presenting groups of disks as logical units. RAID controllerĪ RAID controller is a device used to manage hard disk drives in a storage array. In a multiuser system, better performance requires a stripe wide enough to hold the typical or maximum size record, enabling overlapped disk I/O across drives. In a single-user system where large records are stored, the stripes are typically set up to be small (512 bytes, for example) so that a single record spans all the disks and can be accessed quickly by reading all the disks at the same time. Disk mirroring and disk striping can also be combined in a RAID array.Īn image of a hard drive in a RAID array. The stripes of all the disks are interleaved and addressed in order. Each drive's storage space is divided into units ranging from a sector of 512 bytes up to several megabytes. Striping partitions help spread data over multiple disk drives. Mirroring will copy identical data onto more than one drive. RAID employs the techniques of disk mirroring or disk striping. RAID arrays appear to the operating system (OS) as a single logical drive. Because using multiple disks increases the mean time between failures, storing data redundantly also increases fault tolerance. RAID works by placing data on multiple disks and allowing input/output (I/O) operations to overlap in a balanced way, improving performance. There are different RAID levels, however, and not all have the goal of providing redundancy. RAID (redundant array of independent disks) is a way of storing the same data in different places on multiple hard disks or solid-state drives (SSDs) to protect data in the case of a drive failure.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |