Intel RT3WB080, Hardware User'S Manual

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4 Intel® RAID Controller RT3WB080 Hardware User’s Guide
Redundancy and Error Handling
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In-band and out-of-band SES2.
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Enclosure management support.
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Support the internal SATA Sideband signal SFF-8485 (SGPIO) interface.
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Drive coercion (auto-resizing to match existing disks).
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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.
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Auto-resume on reboot of initialization or rebuild (must be enabled before virtual
disk creation).
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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 read-
modify-write mode. RAID 5 arrays of only three or four drives use Peer Read mode.
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Dirty cache LED plus error reporting for cache write to disk.
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Smart Technology predicts failures of drives and electronic components.
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Patrol Read checks drives and maps bad sectors.
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Commands are retried at least four times.
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Firmware provides best effort to recognize an error and recover if possible.
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Failures are logged from controller and drive firmware, and SMART monitor.
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Failures are logged in NVRAM, viewable from OS Event Log, Intel
®
RAID Web
Console 2; CIM, LEDs, and via alarm.
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Multiple cache options allow configuration-specific performance optimization:
— Write-back: Faster because it does not wait for the disk but data will be lost if
power is lost.
— Write-through: Usually slower but ensures data is on the disk.
— Read Ahead: Predicts next read will be sequential and buffers this data into the
cache.
— Non-Read Ahead: Always reads from the drive after determining exact location
of each read.
— Adaptive Read Ahead: Reads ahead and caches data only if doing sequential
reads.
— I/O setting: Determines whether read operations check the cache before reading
from disks.
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Cache I/O: Checks cache first; only reads disk if data is not in the cache.
✧
Direct I/O: Reads data directly from disk (not cache).
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Redundancy through:
— Configuration stored in non-volatile RAM and on the drives (COD).
— Hot-swap support.
— Optional battery backup for cache memory.