Before getting the answer to this question (especially for the novices), you must know what Raid itself is; only then will you fully understand what a Raid controller is.
What is RAID?
A redundant array of independent disks is called A RAID system; it can also consist of both hardware and software. RAID creates data redundancies by using virtualized physical storage drives.
In this process, you get enhanced performance and create data redundancy. Controller-based RAID is mostly considered as hardware-based RAID, as opposed to server-based RAID.
A server-based RAID is both software-defined and software-hardware hybrids.
What is a RAID Controller?
A card or chip located between the storage drives, usually hard drives, and the operating system is called a Raid controller. Raid provides data redundancy or enhanced performance of your hard disk.
You also get both benefits from most of the Raid levels at the same time. But on SSD, you only get only one benefit from the Raid controller, which is data redundancy.
But there are some SSD drives that are specifically manufactured for Raid, and you get both the features data redundancy and performance simultaneously.
Let’s explore more about the Raid controllers:
Types of Raid controller
Software-Based: Server-Based RAID
Software RAID delivers RAID services from the host. These are software-defined and are hosted in the OS with a hybrid architecture. A hardware component is placed to relieve the load on the CPU.
- Software-only RAID: Software-only RAID is usually included as a native function on the OS. It is the least expensive of the RAID options. The host-based application manages RAID calculations. It is attached to the storage drives using an HBA or native I/O interface. It starts up when the OS loads the RAID driver.
- Hybrid hardware/software RAID: Hybrid hardware/software RAID uses a hardware component to deliver RAID BIOS functions from the motherboard or HBA. This technology adds another layer to the whole process. It is more expensive than the software-only controller. You get the protection of the RAID system even from boot errors, if something happens to the operating system.
Hardware-Based: RAID Controller
There are two different architectures: an external RAID Controller Card and an internal RAID-on-Chip:
- RAID Controller Card: A RAID controller card is a plug-in expansion card. It connects to a PCIe or PCI-X motherboard slot. There are a RAID processor and I/O processors with drive interfaces.
- RAID-on-Chip: Less expensive RAID-on-Chip, which is a single motherboard chip. This chip integrates the host interface, HDD I/O interfaces, the RAID processor, and a memory controller. Firmware starts up RAID during bootup, then transfer control to the drivers.
RAID can be configured in diferent ways. There are different type of RAID configurations starting from RAID 0 to RAID 10. These configurations are set up on the RAID controllers.
Advantages of RAID Controllers
Hardware-based RAID is more expensive than software-based RAID.
- Cache memory. Controller-based RAID provides you with additional disk cache memory, which accelerates RAID operations.
- Dedicated processing. Controller-based systems manage RAID configuration independently apart from the OS. It does not require disk processing power, capacity, and speed win out over software-only RAID.
- Lack of boot errors. Software-only RAID is located on the OS; it is subject to boot errors that can compromise an entire array. Boot errors will not affect RAID controllers.
At 1gbits we have integrated hardware RAID controllers to all our VPS servers. However on request you can get a RAID controller set-up on our dedicated servers also. Get in touch with us via live chat and we will make it happen!