Somat eDAQlite, User Manual

Page: 166 / 228

Somat eDAQ
lite
166 I2773-4.
4
en
DRAM Buffering
Selecting the DRAM buffering mode allocates the circular buffer used for burst data
capture in DRAM memory. Otherwise, the eDAQ
lite
allocates the circular buffer
directly on the Linux file system media. DRAM buffering is only available when using
the internal CompactFlash memory for data storage.
NOTE
SIE file data always uses the DRAM buffering option.
CAUTION
All test data in DRAM memory is lost if the eDAQ
lite
powers down or resets for any
reason.
Selecting the DRAM buffering option is advised as long as the DRAM allocations
required are not too large. Updating the circular buffer allocated in DRAM is very
efficient as is copying the circular buffer filled with a burst record to the PC Card
memory in a linear manner.
Allocating, the circular buffer directly in the PC Card file system memory is somewhat
less efficient in general because of the overhead in constantly writing to the PC Card
memory. Furthermore, for rotating disks, the seeks required when the circular buffer
wraps around will adds a periodic burden to performance efficiency. Also note that
repetitively overwriting the same flash memory area produces wear and reduces the
life of the flash memory.
NOTE
When considering DRAM buffering, note that the eDAQ lite can only copy full burst
records for DRAM to PC Card memory. Not using the DRAM buffering mode allows
the eDAQ
lite to store partial burst records if, for example, the test run stops before the
burst is full.
HBM: public