IBM IC25N020ATDA04 Hard Drive Specifications - Page 37

ECC

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5.8 ECC The 40-byte three interleaved ECC processor provides user data verification and correction capability. The first 4 bytes of ECC are check bytes for user data and the other 36 bytes are Read Solomon ECC. Each interleave has 12 bytes for ECC. Hardware logic corrects up to 15 bytes (5 bytes for each interleave) errors on-the-fly. Following are some examples of error cases. An "O" means that the byte contains no error. An "X" means that at least one bit of the byte is bad. On The Fly correctable Byte # 1 111 1 111 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 Interleave AB C A B CA B C A B CA B C A B C Error pattern Error pattern XXX X XXX XX X X XX XX O OO XXX X XXX XX O O OXXX X XX Error byte # for each interleave A B C 5 5 5 5 5 5 Uncorrectable Byte # Interleave Error pattern Error pattern 1 111 1 111 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 AB C A B CA B C A B CA B C A B C XXX X XXX XX X X XX XX X OO XOOX OOX OOX O OX OO X OO Error byte # for each interleave A B C 6 5 5 6 0 0 Figure 19. Examples of error cases. Travelstar 48GH, 30GN & 15GN hard disk drive specifications 23

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5.8 ECC
The 40-byte three interleaved ECC processor provides user data verification and correction capability.
The first 4 bytes of ECC are check bytes for user data and the other 36 bytes are Read Solomon ECC.
Each interleave has 12 bytes for ECC. Hardware logic corrects up to 15 bytes (5 bytes for each interleave)
errors on-the-fly.
Following are some examples of error cases. An "O" means that the byte contains no error. An "X" means
that at least one bit of the byte is bad.
On The Fly correctable
Byte #
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
1
1
1
1
1
1
1
1
Interleave
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
Error pattern
5
Error byte # for
each interleave
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
O
O
O
Error pattern
5
5
5
5
5
X
X
X
X
X
X
X
X
X
O
O
O
X
X
X
X
X
X
Uncorrectable
Byte #
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
1
1
1
1
1
1
1
1
Interleave
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
A
B
C
Error pattern
6
Error byte # for
each interleave
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
O
O
Error pattern
6
5
5
0
0
X
O
O
X
O
O
X
O
O
X
O
O
X
O
O
X
O
O
Figure 19. Examples of error cases.
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
23