Error Detection And Correction - Sony OA-D30V Manual

SECTION 9
ERROR DETECTION AND CORRECTION
9-1. WRITE ERROR
If an error occurs during a write operation, it will
be detected on the next revolution by doing a read
operation, commonly called a "write check." To
correct the error, another write and write check
operation must be done. If the write operation is
not successful after ten (10) attempts have been
made, a read operation should be attempted on
another track to determine if the media or the
drive is failing. If the error still persists, the disk
should be considered defective and discarded.
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9-2. READ ERROR
Most errors that occur will be "soft" errors; that is,
by performing an error recovery procedure the
data will be recovered.
Soft errors are usually caused by:
1. Airborne contaminants that pass between the
read/write head and the disk. These contami-
nants will generally be removed by the cartridge
self-cleaning wiper.
2. Random electrical noise wh ich usually lasts for
a few J.l sec.
3. Small defects in the written data and/or track
not detected during the write operation which
may cause a soft error during a read.
The following procedures are recommended to
recover from the above mentioned soft errors:
1. Reread the track ten (10) times or until such
time as the data is recovered.
2. I f data is not recovered after using step 1, access
the head to the adjacent track in the same direc-
tion previously moved, then return to the desired
track.
3. Repeat step 1.
4. If data is not recovered, the error is not recover-
able.