Disc Format; Formatting And Defect Management; Record Interleave; Diagnostics - Seagate ST251N Product Manual

2.5 DISC FORMAT
The disc format is flexible and supports either 512 or 1,024 bytes per
sector.
2.5.1 FORMATTING AND DEFECT MANAGEMENT
Media defects are identified and recorded on the disc during the man-
ufacturing process. This defect map is used during formatting and
enables the drive to bypass these defects. During the formatting op-
eration, the controller uses the sector-slip technique to reassign de-
fective sectors.
Sector-slip al lows any sector with a defect to be mapped and bypassed.
The next contiguous sector is given that sector address. The ST251 N/
277N support the following three variations of the format command:
• Format using a combined list of previously defined defects (manu-
facturer's list plus user-defined list)
• Format with previously defined list plus additional user-defined de-
fects
• Format with manufacturer's list only (removes all user-defined de-
fects)
2.5.2 RECORD INTERLEAVE
The ST251 N/277N support user-specified record interleaves of from 1
to 1 (records formatted sequentially on the disc) through the number
of records per track minus one. This gives the user, the ability to con-
figure the drive for maximum performance within the operating envi-
ronment.
2.6 DIAGNOSTICS
At power-on the ST251 N/277N wi II execute a series of diagnostic tests.
Any failure will be indicated by a series of LED flashes. The first failure
will be preserved. Any power-up failure will result in sense code 29H,
2-4 ST251Nl277N Product Manual, Rev. B