Hello, all!
This post will discuss RAID technology with you.
1. What is RAID?
RAID (Redundant Array of Independent Disks) is an enabling technology that leverages multiple drives as part of a set that provides data protection against drive failures. In general, RAID implementations also improve the storage system performance by serving I/Os from multiple disks simultaneously.
Two methods to implement RAID:
Hardware RAID. A specialized hardware controller is required, usually in the hosts (servers).
Software RAID, implemented on OS, no additional hardware required. Software RAID is widely adopted in enterprise storage.
A subset of disks within a RAID array can be grouped to form logical associations called logical arrays, also known as a RAID set or a RAID group.
2. Striping
Striping is a technique to spread data across multiple drives to make drivers working in parallel. All drivers work simultaneously, allowing more data to be processed in a shorter time and increasing performance, compared to reading and writing from a single disk.
Strip: in each disk of RAID set, a predefined number of contiguously addressable disk blocks.
Stripe: The set of strips that spans across all the disks in the RAID set.
Stripe size: multiple of strip size by number of data disks in the RAID set.
Stripe depth (Strip size): the number of blocks in a strip and is the maximum amount of data that can be written to or read from a single disk in the set.
Stripe width: the number of data strips in a stripe.
In a five disk striped RAID set with a strip size of 64KB, the stripe size is 320KB(64KB*5). Stripe width is 5.
That's all, thanks!
