Declustered array parameters

Declustered arrays have four parameters that can be set using stanza parameters when creating a declustered array, and can be changed using the mmchrecoverygroup command with the --declustered-array option. These are:

dataSpares

The number of disks' worth of equivalent spare space used for rebuilding vdisk data if pdisks fail. This defaults to one for arrays with nine or fewer pdisks, and two for arrays with 10 or more pdisks.

vcdSpares

The number of disks that can be unavailable while the IBM Storage Scale RAID server continues to function with full replication of vdisk configuration data (VCD). This value defaults to the number of data spares. To enable pdisk-group fault tolerance, this parameter is typically set to a larger value during initial system configuration (half of the number of pdisks in the declustered array + 1, for example).

replaceThreshold

The number of disks that must fail before the declustered array is marked as needing to have disks replaced. The default is the number of data spares.

scrubDuration

The number of days over which all the vdisks in the declustered array are scrubbed for errors. The default is 14 days.