noun
hot spare
Computing term for a redundant component (e.g., a disk) that is powered on and ready to take over immediately if an active component fails.
RAID構成では、ホットスペアを用意しておくと障害時に自動で再構築が始まる。
In a RAID configuration, if you have a hot spare ready, rebuilding starts automatically when a failure occurs.
Variant with interpunct; less common in running text.
A cold spare is a backup component that is not powered on and must be manually activated, unlike a hot spare which is always ready.
Borrowed from English 'hot spare', referring to a standby component kept powered and ready for immediate use.