Redundancy And Error Handling - Intel SRCSATAWB Hardware User's Manual

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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Activity and fault indicators per drive.
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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
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
— 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
— Non Read Ahead. Always reads from the drive after determining exact location
— Adaptive Read Ahead. Reads ahead and caches data only if doing sequential
— I/O setting. Determines whether read operations check the cache before reading
3
power is lost.
cache.
of each read.
reads.
from disks.
✧ 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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