Intel SRCSASLS4I - RAID Controller, Hardware User'S Manual

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4 Intel® RAID Controller SRCSASLS4I Hardware User’s Guide
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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.
✧
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 nonvolatile RAM and on the drives (COD).
— Hot-swap support.
— Optional battery backup for cache memory. Controller provides fast or trickle
charges.
SAS/SATA Features of the 1078 Controller
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Provides four independent phys, each supporting 3.0 Gbps SATA data transfers.
•
Scalable interface that supports up to 16 physical devices and 64 logical devices via
expanders.
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Supports SSP to enable communication with other SAS devices.
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Supports SMP to communicate topology management information.
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Supports single PHY or wide ports consisting of 2, 3, or 4 PHY within one quad
port.
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Allows addressing of multiple SATA targets through an expander if using SATA 2.0-
compliant hard disk drives.
•
Allows multiple initiators to address a single target (in a fail-over configuration)
through an expander.