Use hot-spare disks to automatically replace failed disks in a RAID environment.
Upon a disk failure in a RAID array is detected, the RAID adapter will look into all disks it controls for a hot-spare disk. If one is available, the RAID adapter will replace the role of the failed disk in the RAID array with the hot-spare disk. The data and parity are rebuilt from the survival member disks automatically. The RAID array is changed back to optimized state when the rebuild is complete.
It is important to note that a hot-spare disk will only replace a disk in an the array tier of the same device class as the hot spare. Therefore, you need different hot-spare disks available to fully cover all array device classes under the adapter. tiers in a tiered RAID level. For example, a 4K SSD hot spare is needed for an array composed of 4K SSDs and a 4K HDD hot spare is needed for an array composed of 4K HDDs.
- 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 (Mainstream) 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. To assign a disk for use as a hot spare, it must be formatted for advanced function.
For disk arrays with Easy Tier® function, it is important to note that a hot-spare disk will only replace a disk in the tier that has the similar performance characteristics as the hot spare. So, you need different hot-spare disks to fully cover all tiers in a tiered RAID level. For example, an SSD hot spare and a HDD hot spare.