154 Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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Notes for Table 5.2.1-24. Format Parameter Page (continued)
[1] The only time his page of parameters may be sent is immediately before sending a Format Unit com-
mand to the disc drive. The Current parameters for this page are updated immediately but any changes
between these Current parameters and the existing media format are not in effect until after the Format
Unit command is completed. A PS bit of 1 indicates this page is savable. The PS bit is not used with the
Mode Select command.
[2] The Tracks per Zone* field indicates the number of tracks the disc drive allocates to each defect manage-
ment zone. Seagate drives define a defect management zone as one track or one cylinder. A programmed
value of 1 defines one track per zone (i.e. spare sectors per track). Any other recorded value results in
the drive defining one cylinder as the defect management zone and the drive automatically inserts the
number of read/write heads (i.e. number of tracks per cylinder) in this field. Default value is usually 1, but
see individual drive Product Manual.
[3] The Alternate Sectors per Zone* field indicates the number of spare sectors to be reserved for the
defined defect management zone. A value of zero indicates that no sectors are to be reserved in each
zone for defect management. This is to accommodate hosts that want to manage the defects them-
selves.
[4] The Alternate Tracks per Zone* field indicates the number of spare tracks to be reserved at the end of
each defect management zone. A value of zero indicates that no spare tracks are to be reserved in each
zone for defect management by the disc drive.
[5] The Alternate Tracks per Volume field indicates the number of spare tracks to be reserved at the end of
the drive volume. The disc drive uses these locations for replacing defective sectors. A value of zero
indicates that no spare tracks are to be reserved at the end of the unit for defect management. Typically
the disc drive defaults to two times the number of read/write heads in the drive, which amounts to two
spare cylinders. The initiator may change this value for a number between 0 and 255 that is a multiple of
the total number of Data Read/Write heads installed.
[6] The Sectors per Track field indicates the
average number of physical sectors the disc drive has per disc
track. This value depends on the selected sector size and ZBR zones. The number of user accessible
sectors per track may be fewer than the reported value, since sectors per Track includes sectors set
aside for defect management. This value cannot be used to calculate drive user accessable capacity.
Note. The value cannot be directly selected with the Mode Select command, but is a report of how the
drive is configured.
[7] The Bytes per Physical Sector field indicates the number of data bytes the disc drive shall allocate per
physical sector. This value equals the block length reported in the Mode Sense block descriptor. The
bytes per physical sector is not directly changeable by the initiator and is not verified on a Mode Select
command.
*
Defect management zone (one or more tracks), NOT a ZBR (variable track capacity recording) zone.
ZBR zones are referred to as notches (page 0Ch is the Notch page).
The actual implimentation of reserving spare areas for defect management takes place during the Format
Unit command.
