Understand the Terms Used in This Site

When reading or learning about RAID systems on this site there are a number of terms that you are likely to come across frequently:

Mirroring

Mirroring is exactly what it sounds like, that is, creating an identical 'mirror' copy of data from one server onto another.  This system is used in RAID 1 systems (sometimes known simply as, mirrored arrays ).  When data is mirrored every bit, every byte, every word and every sector is copied identically to at least one other media, although the limit of the amount of mirror copies that can be made is simply down to what your hardware or software will support.

Striping

Striping is very different to mirroring, and is available in many forms.  Striping plays an extremely important role in many RAID systems including:

RAID 0        RAID 1        RAID 5
RAID 2        RAID 4        RAID 6, to name but a few.

When data is striped the data is split up into chunks, normally either by a defined block size or at the byte level, these chunks are then written to independent storage media so that the task of writing and reading is shared across all member devices.

Parity

Parity is a method of redundancy generation used by many RAID levels whereby a calculation is performed on the data within an array to create a set of data that can be used to recreate any lost data, for example that caused by a hard drive failure in a RAID 5 array.

Parity in its most commonly used form is found on a RAID 5 system, where a process known as XOR is used to generate a block of information based upon the contents of the same block on the remaining storage media