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4.9.1
PCI Bridge/CPU
4.9.2
Cache Memory
4.9.3
MegaRAID BIOS
Table 4.6
MegaRAID SCSI 320-1 Specifications (Cont.)
Parameter
SCSI connectors
Serial port
MegaRAID SCSI 320-1 uses the Intel GC80302 PCI bridge with an
embedded 80960JT RISC processor running at 66 MHz. The GC80302
bridge handles data transfers between the primary (host) PCI bus, the
secondary PCI bus, cache memory, and the SCSI bus. The DMA
controller supports chaining and unaligned data transfers. The
embedded 80960JT CPU directs all controller functions, including
command processing, SCSI bus transfers, RAID processing, drive
rebuilding, cache management, and error recovery.
MegaRAID SCSI 320-1 cache memory resides in an onboard memory
bank that uses 2 M x 72 (16 Mbyte), 4 M x 72 (32 Mbyte), 8 M x 72 (64
Mbyte) or 16 M x 72 (128 Mbyte) unbuffered 3.3 V SDRAM. Possible
configurations are 8, 16, 32, 64, or 128 Mbytes. The maximum
achievable memory bandwidth is 528 Mbytes/s.
MegaRAID supports write-through or write-back caching, which can be
selected for each logical drive. To improve performance in sequential disk
accesses, MegaRAID does not use read-ahead caching for the current
logical drive. The default setting for the read policy is Normal, meaning
no read-ahead caching. You can disable read-ahead caching.
Warning:
Write caching is not recommended for the physical drives.
When write cache is enabled, loss of data can occur when
power is interrupted.
The BIOS resides on a 1 MB × 8 flash ROM for easy upgrade. The
MegaRAID BIOS supports INT 13h calls to boot DOS without special
MegaRAID SCSI 320-1 Specifications
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
Specification
One 68-pin internal high-density connector for 16-bit
SCSI devices. One very-high density 68-pin external
connector for Ultra and Wide SCSI.
3-pin RS232C-compatible berg
4-7
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