令和5年度 ITパスポート試験問63

This question's explanation and your answers so far.

問63

頻出度★★☆

容量が500GバイトのHDDを2台使用して，RAID0，RAID1を構成したとき，実際に利用可能な記憶容量の組合せとして，適切なものはどれか。

出典　令和5年度 ITパスポート試験問63

解説

問 63

Incorrectア
Stating RAID0 as 1 TB is correct, but stating RAID1 as 1 TB is wrong. RAID1 uses mirroring to duplicate the same data onto 2 disks, so the usable capacity is halved to 500 GB.
イ
正解 RAID0 is a method called striping, which distributes data across the 2 disks; since it has no redundancy (backup), the full capacity of both disks can be used directly, giving 500 GB + 500 GB = 1 TB. RAID1, on the other hand, is called mirroring and stores the same data duplicated on 2 disks, so in effect only the capacity of one disk is usable, namely 500 GB. Therefore the combination RAID0: 1 TB, RAID1: 500 GB, which is choice イ, is correct.
Incorrectウ
Stating RAID0 as 500 GB is wrong. RAID0 uses striping and has no redundancy, so the capacities of the 2 disks are combined and usable directly, giving 1 TB. The RAID1 value of 1 TB is also wrong.
Incorrectエ
Stating RAID1 as 500 GB is correct, but stating RAID0 as 500 GB is wrong. RAID0 can combine the capacities of the 2 disks, giving 1 TB.

ここがポイント

RAID0 (striping) distributes data across multiple disks to improve speed; in exchange for having no redundancy, the full capacity (500 GB × 2 = 1 TB) can be used.
RAID1 (mirroring) duplicates the same data onto 2 disks to improve fault tolerance; the usable capacity is halved to that of a single disk (500 GB).

用語

解答問63イ