|
The most widespread standard for configuring multiple hard drives is RAID (Redundant Array of Inexpensive/Independent Disks), which comes in a number of standard configurations and non-standard configurations. Non-RAID drive architectures also exist, and are referred to by acronyms with similarity to RAID, several tongue-in-cheek: * JBOD (derived from "just a bunch of disks"): an architecture involving multiple hard drives, while making them accessible either as independent hard drives, or as a combined (spanned) single logical volume with no actual RAID functionality. * SPAN or BIG: A method of combining the free space on multiple hard drives to create a spanned volume. Such a concatenation is sometimes also called JBOD. A SPAN or BIG is generally a spanned volume only, as it often contains mismatched types and sizes of hard drives. * MAID (derived from "massive array of idle drives"): an architecture using hundreds to thousands of hard drives for providing nearline storage of data, primarily designed for "Write Once, Read Occasionally" (WORO) applications, where increased storage density and decreased cost are traded for increased latency and decreased redundancy. == == JBOD (abbreviated from "just a bunch of disks") is an architecture using multiple hard drives, but not in a RAID configuration, thus providing neither redundancy nor performance improvements. Hard drives may be handled independently as separate logical volumes, or they may be combined into a single logical volume using a volume manager like LVM; such volumes are usually called "spanned". When combined into a single logical volume, JBOD configurations are also called "linear", as separate hard drives are concatenated in a linear manner to form a logical volume. Due to its nature, no redundancy is provided with this configuration, meaning that failure of a single hard drive destroys the logical volume as a whole. mdadm, in addition to LVM, supports creation of such non-RAID linear volumes.〔(【引用サイトリンク】 LVM HOWTO, Section 3.7. mapping modes (linear/striped) )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Non-RAID drive architectures」の詳細全文を読む スポンサード リンク
|