Intel SRCU31, User Manual

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Getting Started 29
Table 2. RAID Level, Hard Disk Drives, and Usable Storage Capacity
RAID Level
Available
Capacity with
2 Hard Disk
Drives
*
Available
Capacity with
3 Hard Disk
Drives
*
Available
Capacity with
4 Hard Disk
Drives
*
Available
Capacity with
5 Hard Disk
Drives
*
RAID 0 2 GB 3 GB 4 GB 5 GB
RAID 1 1 GB 1 GB 1 GB 1 GB
RAID 4 NA 2 GB 3 GB 4 GB
RAID 5 NA 2 GB 3 GB 4 GB
RAID 10 NA NA 2 GB NA
* Each hard disk drive is assumed to have 1 GB capacity.
Are Hot Fix Drives Needed?
Assume that one of the hard disk drives of the RAID 5 disk array fails (Hot Fix drives are available
with RAID 1, 4, 5, and 10 arrays). The disk array is without redundancy. Time Without
Redundancy (TWR) starts to run. Any unnecessary prolongation of the TWR (the time required to
get a replacement drive, or because you did not immediately recognize the failure) increases the
risk of data loss that will occur should a second drive fail. Therefore, redundancy should be
restored as soon as possible and in an automated manner. Integrating a Hot Fix drive (also referred
to as hot spare) as an immediately available and auto-replacing drive is the most effective way to
keep the TWR as short as possible. Only a Hot Fix drive can ensure optimal disk array security and
constant data availability.
Using a Hot Fix drive is not compulsory. If you control the disk array at regular intervals and
immediately replace a defective drive (by shutting down the system or hot-plugging), you can
operate the system without a Hot Fix drive.
Intel RAID Controller Hardware Features
This section provides a summary of the key features, configuration options, and support interface
technology supported by the Intel RAID Controller SRCU31.
Architecture Features (HW)
Table 3. Hardware Architecture
Component Features
CPU Intel
®
i960
®
RN I/O Processor, 100 MHz, RISC 32-bit core. This
controller features hardware XOR support for high speed RAID 5
parity calculations.
Memory/Cache 3.3v, unbuffered PC100, ECC, SDRAM DIMM expandable to 32, 64,
or 128 MB.
Cache Downstream Write Through, Full and Sequential
Write-Back - Selectable per volume.
Firmware ROM Type, Flash EEPROM, 2 Mb x 8 (flashable).
PCI Transfer Rate: 264 MB/sec.
Array Interface to Host Interface to Host PCI 2.2.
PCI Signaling Capable of being used in a 5 or 3.3 volt slot.