36 Storage Controller FeaturesAutomatic Replace Member with Predicted FailureA Replace Member operation can occur when there is a SMART predictivefailure reporting on a physical disk in a virtual disk. The automatic ReplaceMember is initiated when the first SMART error occurs on a physical diskthat is part of a virtual disk. The target disk needs to be a hot spare thatqualifies as a rebuild disk. The physical disk with the SMART error is markedas failed only after the successful completion of the Replace Member. Thisavoids putting the array in degraded status.If an automatic Replace Member occurs using a source disk that wasoriginally a hot spare (that was used in a rebuild), and a new disk added forthe Replace Member operation as the target disk, the hot spare reverts to thehot spare state after a successful Replace Member operation.NOTE: To enable the automatic Replace Member, use the Dell OpenManagestorage management application. For more information on automatic ReplaceMember, see "Dell OpenManage Storage Management" on page 81.NOTE: For information on manual Replace Member, see "Replacing an OnlinePhysical Disk" on page 110.Controller Cache PreservationThe controller is capable of preserving its cache in the event of a systempower outage or improper system shutdown. The PERC H700 controllers areattached to a Battery Backup Unit (BBU) that provides backup power duringsystem power loss to preserve the controller's cache data. The PERC H800 hasa transportable version of the BBU attached to it called the TransportableBattery Backup Unit (TBBU) which enables the entire cache module to betransported to a new controller if necessary. If the card has the optional non-volatile cache (NVC) or transportable non-volatile cache (TNVC) module,the cache data is preserved using flash storage instead of battery power.
