The drives which are used to build failed drives data is called Hot Spare drives. These hot sparing drives should be compatible with the failed drives.
From VNX OE for Block 5.33, any unbound drive can be considered as spare. EMC recommends to configure hot spare policy to spare 1 per 30 disks.
The following steps outlines the steps to configure Hot Sparing on EMC VNX systems.
1. Login to EMC Unisphere and navigate to appropriate VNX system
3. Select appropriate Disk Type to configure Hot Spare Policy. In this example, if you observe NL SAS drives, Hot Spare Policy configured as “No Hot Spares” It doesn’t mean that there will be no hot spares for NL SAS drives. Any unbound drive will be used as Hot Spare drive if a drive failure occurs.
4. If you want to change the Hot Spare policy, select appropriate disk type, select Hot Spare Policy as “ Recommended” or “Custom” and change number of disks in “keep unused per policy’ row.
It’s recommended to ensure that unbound drives are available for each drive type installed on system. For example, if you have SAS and NL-SAS installed on system there should be unbound SAS and NL-SAS available as hot spare drives.