10 Differences Between AHCI and RAID You Should Know

Filed in Articles by on May 18, 2021

Difference Between AHCI and RAID: IDE and AHCI are peripheral components interconnect (PCI) devices that move data between system memory and SATA controllers. They both provide advanced features to the Serial ATA standard and add more advanced storage features.

Advanced Host Controller Interface

Advanced Host Controller Interface (AHCI) is an Intel computer standard that is limited to Intel chipsets. AHCI has been around since 2004, where it replaced the older IDE/Parallel ATA interface in new devices.

However, it can only process a limited number of IQ requests, because it can only hold 32 I/O requests in the queue. Native Command Queuing (NCQ) accelerates AHCI large file transfer performance on HDDs by minimizing read/write head movements and speeding up access time. Although NCQ works with SSDs, it is not terribly useful since SSDs have no moving parts.

AHCI supports Windows, Linux, and UNIX operating systems. Note that SATA SSDs do not use AHCI, which is the software protocol between the CPU and the SATA controller.

The much newer NVMe standard is replacing AHCI-enabled SSDs in high-performance environments. NVMe (non-volatile memory express) interfaces between NAND flash and SSDs using PCIe cards. AHCI has a limited queue depth of 32. NVMe significantly reduces latency and supports queue depths of 65,000.

Redundant Array of Inexpensive Disk

RAID (redundant array of independent disk) is another mature technology but is widely deployed in storage environments.

It provides high availability and data protection across multiple nodes, which enables HDDs and SSDs to keep running after the loss of a device. RAID is available for SSD arrays. But since it does not accelerate SSD performance, all-flash arrays are likelier to use proprietary RAID that provides redundancy and accelerates performance on SSDs.

Storage admins may install RAID either as a hardware controller card or chip or as software with or without a hardware component. A RAID controller card is a plug-in expansion card that connects to a PCIe or PCI-X motherboard slot.

They are independent of the host, so all RAID operations are offloaded from the CPU to the dedicated card. RAID-on-Chip sits on the motherboard and integrates the host interface, I/O interfaces for HDDs, the RAID processor, and a memory controller.

Notable Distinctions Between AHCI and RAID

1. AHCI is more of an operation for SATA drives. However, RAID is an advanced mechanism that provides performance enhancements by using multiple hard drives in different configurations.

2. RAID is a much older technology compared to AHCI.

3. AHCI is pretty much exclusive to computers with Intel chipsets while RAID functionality is offered by a wide variety of vendors.

4. RAID mode in SATA also exposes the same functionality that AHCI does.

5. RAID is more advantageous for people compared to AHCI if they are willing to spend extra cash on additional hard drives.

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CSN Team.

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