Intel RS2WC040 Hardware User Guide - Page 14

Redundancy and Error Handling • In-band SES2. • Enclosure management support. • Drive coercion (auto-resizing to match existing disks). • Support the internal SAS Sideband signal SFF-8485 (SGPIO) interface. • Auto-detection of failed drives with transparent rebuild. There must be disk activity (I/O to the drive) for a missing drive to be marked as failed. • Auto-resume on reboot of initialization or rebuild (must be enabled before virtual disk creation). • Smart initialization automatically checks consistency of virtual disks if there are five or more disks in a RAID 5 array, which optimizes performance by enabling readmodify-write mode. RAID 5 arrays of only three or four drives use Peer Read mode. • Smart Technology predicts failures of drives and electronic components. • Patrol Read checks drives and maps bad sectors. • Commands are retried at least four times. • Firmware provides best effort to recognize an error and recover if possible. • Failures are logged from controller and drive firmware, and SMART monitor. • Failures are logged in NVRAM, viewable from OS Event Log, Intel® RAID Web Console 2; CIM, LEDs. • Cache options: - Write-through: Usually slower but ensures data is on the disk. - Normal Read: Always reads from the drive after determining exact location of each read. - Direct I/O: Reads data directly from disk without checking cache first. • Access policy: - RW: allow read and write I/O - Read Only: allow read I/O only - Blocked: deny read and write I/O • Redundancy through: - Configuration stored in non-volatile RAM and on the drives (COD). - Hot-swap support. SAS/SATA Features of the LSISAS2008 Controller • Provides eight independent phys, each supporting 6 Gb/s and 3 Gb/s SAS data transfers per PHY, only four phys are utilized by the RAID adapter. • Supports SSP to enable communication with other SAS devices. 4 Intel® RAID Controller RS2WC040 Hardware User's Guide