Quantum FIREBALL PLUS AS 10.2 User Manual

Basic Principles of Operation
5-15 Quantum Fireball Plus AS 10.2/20.5/30.0/40.0/60.0 GB AT
complex firmware ECC algorithm, the drive will always try to recover from an error
by attempting to re-read the data correctly. This strategy prevents invoking
correction on non-repeatable errors. Each time a sector in error is re-read a set of
ECC syndromes is computed. If all of the ECC syndrome values equal zero, and xc
syndrome value equals to 0 or 0FF, the data was read with no errors, and the sector
is transferred to the host system. If any of the syndrome values do not equal zero,
an error has occurred, the syndrome values are retained, and another re-read is
invoked.
Note:
Note:Note:
Note: Non-repeatable errors are usually related to the signal to noise ratio
of the system. They are not due to media defects.
This event may be significant depending on whether the automatic read reallocation
or early correction features have been enabled. If the early correction feature has
been enabled and a stable syndrome has been achieved, firmware ECC correction is
applied, and the appropriate message is transferred to the host system (e.g.,
corrected data, etc.).
Note:
Note:Note:
Note: These features can be enabled or disabled through the ATA Set
Configuration command. The EEC bit enables early firmware ECC
correction before all of the re-reads have been exhausted. The ARR
bit enables the automatic reallocation of defective sectors.
The Quantum Fireball Plus AS AT drives are shipped from the fac-
tory with the automatic read reallocation feature enabled so that
any new defective sectors can be easily and automatically reallocat-
ed for the average AT end user.
5.3.4
5.3.45.3.4
5.3.4 Defect Management
Defect ManagementDefect Management
Defect Management
In the factory, the media is scanned for defects. If a sector on a cylinder is found to
be defective, the address of the sector is added to the drive’s defect list. Sectors
located physically subsequent to the defective sector are assigned logical block
addresses such that a sequential ordering of logical blocks is maintained. This inline
sparing technique is employed in an attempt to eliminate slow data transfer that
would result from a single defective sector on a cylinder.
If more than 32 sectors are found defective, the above off-line sparing technique is
applied to the 32 sectors only. The remaining defective sectors are replaced with the
nearest available pool of spares.
Defects that occur in the field are known as grown defects. If such a defective sector
is found in the field, the sector is reallocated according to the same algorithm used
at the factory for those sectors that are found defective after the first 32 spares per
pool of spares; that is, inline sparing is not performed on these grown defects.
Instead, the sector is reallocated to an available spare sector on a nearby available
pool of spares.
Sectors are considered to contain grown defects if the 14/15/16 10-bit symbols ECC
algorithm must be applied to recover the data. If this algorithm is successful, the
corrected data is stored in the newly allocated sector. If the algorithm is not
successful, a pending defect will be added to the defect list. Any subsequent read to
the original logical block will return an error if the read is not successful. A host
command to over-write the location will result in 4 write/read/verifies of the
suspect location. If any of the 4 write/read/verifies fail, the new data will be written
to a spare sector, and the original location will be added to the permanent defect
list. If all 4 write/read/verifies pass, data will be written to the location, and the
pending defect will be removed from the list.

Quantum FIREBALL PLUS AS 10.2 Specifications

General

Brand	Quantum
Model	FIREBALL PLUS AS 10.2
Category	Storage
Language	English