Table 4.6 MegaRAID SCSI 320-1 Specifications (Cont.)
Parameter | Specification |
| |
SCSI connectors | 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. |
| |
Serial port | 3-pin RS232C-compatible berg |
| |
4.9.1PCI Bridge/CPU
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.
4.9.2Cache Memory
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.
4.9.3MegaRAID BIOS
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 | 4-7 |
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