Using hot-spare disks

Hot-spare disks are used to automatically replace a disk that has failed in a redundant RAID environment. For disk arrays, it is important to note that a hot spare disk will only replace a disk in an array of similar device class as that of the hot spare. Therefore, you need different hot spare disks to fully cover all the array device classes under the adapter. For example, a 4K SSD hot spare is needed for an array of 4K SSDs and a 4K HDD hot-spare disk is needed for an array of 4K HDDs.

A RAID array must be entirely composed of devices from one of the following device classes:

• 528 HDDs (10K or 15K)
• 4K HDDs (10K or 15K)
• 4K Nearline HDDs
• 528 SSDs
• 4K SSDs
• 528 Read Intensive (Mainstream) SSDs
• 4K Read Intensive (Mainsteam) SSDs

Hot-spare disks are useful only if their capacity is greater than or equal to that of the smallest capacity disk in an array that becomes degraded.