[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk Interfaces and Configuration | Small Computer Systems Interface (SCSI) | SCSI Configuration ]

BIOS Issues

SCSI hard disks do not suffer from most of the BIOS "barrier" issues that plague IDE/ATA hard disks, because they do not have to deal with the severe restrictions that result from the incompatible IDE and BIOS geometry specification limits. SCSI by its nature uses logical block addressing (LBA) to address devices, and does not rely on the system BIOS for geometry information as IDE/ATA does.

Since SCSI hard disks are controlled by the internal SCSI bios on the host adapter, this gets around the issues inherent with the motherboard's BIOS. However, it means that any limits of the host adapter BIOS can affect access to devices it controls. Some older host adapters did have problems that made them unable to access hard disks over 1 GB in size, or some other arbitrary limits. Newer host adapters should not have these limitations. Of course, if you are using the FAT file system, you are still restricted to 2 GB per partition, since this is a file system issue, not a hardware or BIOS one. See here for a full discussion.of this barrier.

Next: SCSI Software Interface Protocols (ASPI and CAM)

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