問78
頻出度★★☆
RAID の利用目的として, 適切なものはどれか。
平成21年度 秋期 ITパスポート試験 問78
テクノロジ系システム構成要素 › システムの構成
This question's explanation and your answers so far.
解説
問 78
- ア
正解 RAID is a technology that treats several hard disks together as a single logical disk, and it has two main purposes: improving performance and improving reliability (fault tolerance). Striping (RAID 0), which splits data and reads and writes it in parallel across several disks, makes access faster. Mirroring (RAID 1), which writes the same data twice, and schemes that distribute error-correcting parity across the disks (such as RAID 5) let the system keep running without losing data even if one disk fails. Choice ア states both the speed gained by distributed writing and the improvement in fault tolerance, which is exactly what RAID is used for.
Incorrectイ
Putting several hard disks into a small enclosure to save installation space is only a matter of implementation convenience or a selling point for space-saving products; it is not the purpose of RAID. RAID does not define how disks are physically housed, but how data is arranged across several disks (redundancy and distribution).
Incorrectウ
Storing a large number of files across multiple generations describes backup with generation management. RAID mirroring only keeps copying the latest state, so anything deleted or overwritten by mistake is lost on both disks at the same time and cannot be restored from an earlier generation. The key point is that RAID is not a substitute for backup.
Incorrectエ
Sharing disks among several PCs over a network is the role of NAS (network attached storage), a file server, or a SAN. RAID itself has no network-sharing mechanism; it is a technology that bundles disks inside a single computer or storage unit. (RAID may also be used inside a NAS, but the two are different concepts.)
ここがポイント
- RAID treats several hard disks as one logical disk, using striping for speed and mirroring or parity for fault tolerance (redundancy).
- RAID is a mechanism for tolerating failures; its purpose differs from generation-managed backup (ウ) and network sharing by a NAS (エ).
用語