Publication 6181P-UM001G-EN-P - July 2008
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Solid State Drive
Appendix
D
Operation
The solid state drive appears to the system host as a standard rotating
hard drive when powered up. The system host identifies the solid
state drive during powerup and sets the IDE bus speed to reflect the
drives capability:.
•
DMA-2 (multiword) or
•
PIO-4
In DMA-2 or PIO-4, the maximum IDE bus speed is 16.7 M.
The controller on the solid state drive uses an error correcting code
(ECC) and cyclic redundancy check (CRC) to check for data errors.
The ECC code consists of six bytes per 512 bytes (one sector) and is
stored with the data in flash memory.
Data correction algorithms can prevent data corruption on the drive.
However, they cannot prevent operating system (OS)/file type errors
when the OS breaks large files into smaller (multiple) file transfers.
This results in the host receiving only part of the transfer.
Always shutdown your windows application using the Start menu on
the desktop. Whenever possible, use an uninterruptible power source
(UPS) or other power conditioning device to perform a proper
shutdown during unexpected power interruptions.
Life Expectancy
The limitation of the solid state drive is the finite amount of writes to a
specific memory location. The life expectancy of a solid state drive
varies depending on:
•
how often an application writes data to the drive.
•
the size of the file written to the drive.
•
the amount of available space on the drive that can be used by
the drive’s controller to write data.
•
the write/erase cycle limitation the manufacturer specifies.
On the flash drive, the smallest space that can be written to is a sector,
which is 512 bytes. However, the smallest space that can be erased is
a block of memory. Unlike magnetic media, an erase cycle is required
for flash memory before a write can be made. The actual block size
varies depending on the overall capacity of the flash drive, for
example, 63 sectors, or 32 K on a 4 GB drive.
IMPORTANT
Always protect your system against unexpected power
interruptions.
