The hot spare disk is meant to "replace" user data only and is not meant for supporting the vault drives (first five drives which has the FLARE code). This is because the first enclosure which has the vault drives has some extra power protection (from the Standby Power Supply) and the hot spare which might have replaced it could have been in some other enclosure.  In short, the hot spare will not kick in and rebuild the data stored in FLARE drives. You can find more information in the hot spare whitepaper on Powerlink.
 Hi,  One of the FLARE OS HD (i.e. Bus 0 Enclosure 0 Disk 2) is faulty.  We find that the hotspare disk doesn't "reconfigure" to replace that that faulty disk.  We believe that it is due to the configuration / setting of the FLARE OS HD that cannot be replace / reconfigured by the hotspare disk.  Would it be correct ?  Besides, since the FLARE OS Is critical and faulty disk cannot be replaced by hotspare disk, is there any way to keep the failure of both FLARE OS HD from failure ?  We have already have 4 hours replacement contract and the replacement HD & Engineer are already on their way.  Thanks
Does Hotspare disk supports FLARE OS HD failure ?