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Disk Drives Over 1 GByte
AMM-1570/1572 User’s Guide
Stock Number:510526-00, Rev. B Page:D-3
Print Spec Number: 492379-00
Current Date: 3/7/94 ECN Date: 3/8/94
Extended Translation (Using MS-DOS 5.0)
Adaptec host adapters have always supported the full range of disk
drive sizes under all major operating systems. As disk drives have
recently grown beyond 1 GByte in formatted capacity, they have run
up against the DOS 1024 cylinder limit.
To continue its support for all SCSI disk drive capacities under DOS,
Adaptec has introduced an extended translation scheme for the
AMM-1570/1572. This featuresu pports disk drives up to 8 GBytes
in size under DOS. To enable this feature, refer toExtended Transla-
tion for Drive > 1GByte on page 2-15.
The DOS 1 GByte Limit
All currentver sions of DOS are limited to 1024 cylinders per drive.
The standard translation scheme for SCSI host adapters, using 64
heads and 32 sectors, provides a maximum accessible capacity of
1 GByte.
To eliminate the 1 GByte limit, Adaptec's extended translation fea-
ture uses 255 heads and 63 sectors, extending the disk drive cap acity
limit under DOS to 8 GB ytes; the maximum partition size is 2 GByte.
Caution: If you have already partitioned a large disk
drive with one translation method, conversion to
another method will erase your data. Be sure to back up
your disk drive prior to any change in the translation
method used.
When to Use Extended Translation
With MS-DOS 5.0 and Above
NetWare® 386 and the newer versions of UNIX® do not share the
1024 cylinder limit of DOS and do not require extended translation
to support large disk drives.