SanDisk SSD P4 Manuel d'utilisateur télécharger pdf (Page 12)

SanDisk SSD X100 Product Manual (Released) Rev 1.0

1.4 Advanced Flash Management

1.4.1 Defect and Error Management

SSD X100 contains a sophisticated defect and error management system that is similar to the

systems found in magnetic disk drives, and in many cases, offers enhancements. If necessary,

the SSD device will rewrite data from a defective block to a good block. This action is completely

transparent to the host and does not consume any user data space.

The SSD soft error rate specification is much better than the magnetic disk drive specification. In

the extremely rare case that a read error does occur, the SSD X100 products have innovative

algorithms to recover the data by using error detection code and error correction code

(EDC/ECC). These defect and error management systems, coupled with the solid state

construction, give SSD X100 unparalleled reliability.

1.4.2 Wear Leveling

Wear leveling is an intrinsic part of the erase pooling functionality of SSDs using NAND memory.

Advanced features of dynamic and static wear-leveling, and automatic block management are

used to ensure an even distribution of write/erase cycles throughout the entire device,

regardless of how dynamic or static the data written is. This guarantees high data reliability and

maximizes flash life expectancy.

1.4.3 Bad Block Management

Bad blocks are occasionally created during the life cycle of a flash component, in a phenomenon

called dynamic bad-block accumulation. These bad blocks must be marked and replaced

dynamically in order to prevent read/write failures. When a bad block is detected, the

embedded Bad Block Mapping algorithm maps out the block, which will remove the block from

future use.

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SanDisk SSD P4 Manuel d'utilisateur Page 12