Rockwell Automation 6181X-12TPXPDC Industrial Integrated Computers for Hazardous Locations - Manual (Page 62)

62 Rockwell Automation Publication 6181X-UM001B-EN-P - May 2011
Appendix D Solid-state Drive
Application Example One
An application updates a 100 KB data file every second on the 4 GB drive that is
approximately half full with the OS image and application software.
Use this formula to calculate the drive’s expected life span:
(Flash blocks x Write cycle limit x Drive free space) / [(1 block/sec) x (31,536,000sec/yr)]
(32,768 x 2,000,000 x .5) / [ (1 block/sec) x (31,536,000 sec/yr)] = 1039 years
Application Example Two
The OS is updating its FAT table and root directory twice a second. This update
requires one block of memory (128 KB). Every write regardless of location writes
to a single block. In this case, wear leveling is limited to 1 zone (512 blocks).
Use this formula to calculate the drive’s expected life span:
(Flash blocks x Write cycle limit) / [(2 block/sec) x 31,536,000/yr)]
(512 x 2,000,000) / [(2block/sec) x 31,536,000 sec/yr)] = 16.2 years
Normally in a Windows operating environment virtual memory is used, also
known as a swap file or page file. The OS may read from and write to this file
often in a short period of time. Although the space used could be small, an entire
block of memory is required. On systems using solid state memory, we
recommend that this feature be turned off.
Maintenance Under normal operating conditions, scheduled maintenance is not required. The
integrity of data stored on a solid-state drive is good for a minimum of 10 years.