Red Hat Linux System Administration Handbook

Appendix b. Appendix

Problems Using Very Large Hard Disks

Using very large hard disks in PCs can lead to problems because of the limitations of the BIOS and IDE standards on which most PCs are based. Problems arise because the BIOS can manage only hard disks with a maximum of 256 heads, 63 sectors, and 1024 cylinders because the IDE standard is based on a model that specifies the Cylinders, Heads, and Sectors of the hard disks (CHS model), but only allows a maximum of 16 heads, 255 sectors, and 65536 cylinders. The lowest limits of both of these standards combine to give a maximum size for standard hard disks of 504MB (16 heads, 63 sectors, and 1024 cylinders).

The newer Enhanced-IDE (EIDE) standard avoids this limitation by not using the CHS model. ...